Ashley Pearson

Laboratory Evaluation of Commercial Aspheric Aphakic Lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-1983

DOI: 10.1097/00006324-198307000-00007

Abstract: Four types of commercial aspheric aphakic lenses were assessed with respect to mass, spectacle magnification, off-axis power errors, and peripheral distortion. The aspheric lenses have better distortion and off-axis imagery properties than spherical flat back lenses, but the improvement in distortion properties is small for those lenses whose design form specifies a flattish back surface. The claims concerning the distortion properties of these lenses are exaggerated. The shape (bending) of lenses has a large effect on spectacle magnification, peripheral distortion, and off-axis imagery.

Ocular aberrations in the peripheral visual field

Publisher: Optica Publishing Group

Date: 14-04-2008

DOI: 10.1364/OL.33.000863

Abstract: We modified a commercial Hartmann-Shack aberrometer and used it to measure ocular aberrations twice at each of 38 points across the central 42 degrees horizontal x 32 degrees vertical visual fields of five young emmetropic subjects. Some Zernike aberration coefficients show coefficient field distributions that were similar to the field dependence predicted by Seidel theory (astigmatism, oblique astigmatism, horizontal coma, vertical coma), but defocus did not demonstrate such similarity.

Amplitude of Accommodation for Different Head Positions and Different Directions of Eye Gaze

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-1994

DOI: 10.1097/00006324-199405000-00006

Abstract: One of the theories of the mechanism of presbyopia is the Hess-Gullstrand theory. This theory predicts that litude of accommodation should increase in downgaze because of movement of the lens under the influence of gravity, and that this should be more marked for older than for younger subjects. We assessed this theory by measuring the effect of direction of eye gaze and head posture on litude of accommodation for two age groups. Farpoints, nearpoints, and litude of accommodation were determined for two subject groups, a young group aged 18 to 25 years and an older group aged 35 to 45 years. Small but significant shifts of nearpoints toward the eye were observed when head position or eye gaze was shifted from above to below the horizontal, for the younger observers only (the maximum mean difference between conditions was 1.1 D, compared with a mean accommodation level of 9.8 D for this young group). Previous studies by others found changes in the same direction for eye gaze and head position, respectively, but our changes were much smaller. We do not believe that particular care is needed in selection of head position and eye gaze during clinical measurements of the litude of accommodation. Because the shift of the nearpoint was noted only for the younger group, this study does not support the Hess-Gullstrand theory of presbyopia.

Visual and Physiological Optics: where will the journey lead us in 10 years?

Publisher: Wiley

Date: 24-04-2017

DOI: 10.1111/OPO.12384

Spectacle Lens Design – Development and Present State

Publisher: Informa UK Limited

Date: 05-1984

DOI: 10.1111/J.1444-0938.1984.TB02363.X

The Influence of Age on Crystalline Lens Power Calculations

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 18-10-2016

DOI: 10.1167/IOVS.16-20444

Effects of age on peripheral ocular aberrations

Publisher: Optica Publishing Group

Date: 09-03-2010

DOI: 10.1364/OE.18.005840

Measuring ocular aberrations in the peripheral visual field using Hartmann-Shack aberrometry: errata

Publisher: Optica Publishing Group

Date: 17-09-2008

DOI: 10.1364/JOSAA.25.002467

Pupil shape as viewed along the horizontal visual field

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 06-05-2013

DOI: 10.1167/13.6.3

Abstract: Changes in pupil size and shape are relevant for peripheral imagery by affecting aberrations and how much light enters and/or exits the eye. The purpose of this study is to model the pattern of pupil shape across the complete horizontal visual field and to show how the pattern is influenced by refractive error. Right eyes of 30 participants were dilated with 1% cyclopentolate, and images were captured using a modified COAS-HD aberrometer alignment camera along the horizontal visual field to ±90°. A two-lens relay system enabled fixation at targets mounted on the wall 3 m from the eye. Participants placed their heads on a rotatable chin rest, and eye rotations were kept to less than 30°. Best-fit elliptical dimensions of pupils were determined. Ratios of minimum to maximum axis diameters were plotted against visual field angle. Participants' data were well fitted by cosine functions with maxima at (-)1° to (-)9° in the temporal visual field and widths 9% to 15% greater than predicted by the cosine of the field angle . Mean functions were 0.99 cos([ + 5.3]/1.121), R(2) 0.99 for the whole group and 0.99 cos([ + 6.2]/1.126), R(2) 0.99 for the 13 emmetropes. The function peak became less temporal and the width became smaller with increase in myopia. Off-axis pupil shape changes are well described by a cosine function that is both decentered by a few degrees and flatter by about 12% than the cosine of the viewing angle, with minor influences of refraction.

Effect of optical aberrations on the color appearance of small defocused lights

Publisher: Optica Publishing Group

Date: 05-04-2010

DOI: 10.1364/JOSAA.27.000960

Possible Errors in Determining Axial Length Changes during Accommodation with the IOLMaster

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-2004

DOI: 10.1097/00006324-200404000-00015

Abstract: The Zeiss IOLMaster uses partial coherence interferometry to measure the optical path length within the eye. This is converted into the axial length. There are errors in measuring possible changes in axial length as a result of accommodation, because the instrument uses an average refractive index in the eye. We determined the likely extent of these errors. Errors were estimated using Gullstrand's no. 1 schematic eyes. One set of these had the shell structure of the eyes, and another set had the gradient index structure specified by Gullstrand. Errors were 18 to 26 microm for an accommodation of 10.9 D. The worth of the IOLMaster would be increased if it used an equation for conversion from optical length to geometrical length that took into account variations in lens thickness and if it were able to be modified to provide component distances and the axial length using partial coherence tomography.

Do small-aperture presbyopic corrections influence the visual field?

Publisher: Wiley

Date: 27-12-2016

DOI: 10.1111/OPO.12265

Abstract: To explore the effect of small-aperture optics, designed to aid presbyopes by increasing ocular depth-of-focus, on measurements of the visual field. Simple theoretical and ray-tracing models were used to predict the impact of different designs of small-aperture contact lenses or corneal inlays on the proportion of light passing through natural pupils of various diameters as a function of the direction in the visual field. The left eyes of five healthy volunteers were tested using three afocal, hand-painted opaque soft contact lenses (www.davidthomas.com). Two were opaque over a 10 mm diameter but had central clear circular apertures of 1.5 and 3.0 mm in diameter. The third had an annular opaque zone with inner and outer diameters of 1.5 and 4.0 mm, approximately simulating the geometry of the KAMRA inlay (www.acufocus.com). A fourth, clear lens was used for comparison purposes. Visual fields along the horizontal meridian were evaluated up to 50° eccentricity with static automated perimetry (Medmont M700, stimulus Goldmann-size III www.medmont.com). According to ray-tracing, the two lenses with the circular apertures were expected to reduce the relative transmittance of the pupil to zero at specific field angles (around 60° for the conditions of the experimental measurements). In contrast, the annular stop had no effect on the absolute field but relative transmittance was reduced over the central area of the field, the exact effects depending upon the natural pupil diameter. Experimental results broadly agreed with these theoretical expectations. With the 1.5 and 3.0 mm pupils, only minor losses in sensitivity (around 2 dB) in comparison with the clear-lens case occurred across the central 10° radius of field. Beyond this angle, sensitivity losses increased, to reach about 7 dB at the edge of the measured field (50°). The field results with the annular stop showed at most only a slight loss in sensitivity (≤3 dB) across the measured field. The present theoretical and experimental results support earlier clinical findings that KAMRA-type annular stops, unlike circular artificial pupils, have only minor effects on measurements of the visual field.

Influences of accommodation and myopia on the foveal Stiles-Crawford effect

Publisher: Informa UK Limited

Date: 20-11-2009

DOI: 10.1080/09500340902721915

Influence of Stiles–Crawford apodization on visual acuity

Publisher: Optica Publishing Group

Date: 06-2002

DOI: 10.1364/JOSAA.19.001073

Abstract: The Stiles-Crawford effect (SCE) of the first kind has often been considered to be important to spatial visual performance in that it ameliorates the influence of defocus and aberrations. We investigated the influence of SCE apodization on visual acuity as a function of defocus (out to +/-2 D) in four subjects. We used optical filters, conjugate with the eye's entrance pupil, that neutralized or doubled the existing SCE. With an illiterate-E task, the influence of the SCE was more noticeable for myopic defocus than for hypermetropic defocus, was generally more noticeable for high-contrast than for low-contrast letters, and increased with increase in pupil size. The greatest influence on visual acuity of neutralizing the SCE, across the subjects and range of conditions, was deterioration of 0.06 (4-mm pupil), 0.16 (6-mm pupil), and 0.29 log unit (7.6-mm pupil).

Oblique Astigmatism of the Indiana Eye

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-1998

DOI: 10.1097/00006324-199804000-00020

Abstract: Glioblastoma multiforme (GBM) may be susceptible to metabolic strategies such as fasting and ketogenic diets, which lower blood glucose and elevate ketones. Combining these two strategies may be an ideal approach for sustaining a potentially therapeutic glucose ketone index (GKI). In this prospective case series, we observed whether a combined metabolic strategy was feasible, safe, and capable of sustaining a GKI <6 in patients with GBM. We provided recommendations and guidelines to 10 GBM patients at various stages of tumour progression and treatment that enabled them to complete a 5-7-day fast every 1-2 months combined with a modified ketogenic diet during the intervening weeks. Patients monitored their blood glucose and ketone levels and body weight. Adverse effects were assessed. Patients completed a mean of 161 ± 74 days of the combined metabolic strategy, with 34 ± 18 (21%) days of prolonged fasting (mean fast duration: 6.0 ± 1.4 days) and 127 ± 59 (79%) days on the ketogenic diet. The mean GKI for all 10 patients was 3.22 (1.28 during the fasts, 5.10 during the ketogenic diet). Body weight decreased by 8.4 ± 6.9 kg (11.2% decrease in baseline weight). The most common adverse effects attributed to the fasts and ketogenic diet were fatigue, irritability, and feeling lightheaded. The metabolic strategy did not interfere with standard oncological treatments. This is the first study to observe the feasibility and safety of repeated, prolonged fasting combined with a modified ketogenic diet in patients with GBM. Using minimal support, patients maintained the combined metabolic strategy for 5-6 months while sustaining a potentially therapeutic mean GKI of 3.22. Weight loss was considerable. Adverse effects attributed to the metabolic strategy were mild, and it did not interfere with standard oncological treatments. Study Registration: This study is registered on the Australia New Zealand Clinical Trials Registry, number ACTRN12620001310954. The study was registered on 4 December 2020.

Effect of text type on near work-induced contrast adaptation in myopic and emmetropic young adults

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 27-02-2013

DOI: 10.1167/IOVS.12-11496

Abstract: Contrast adaptation has been speculated to be an error signal for emmetropization. Myopic children exhibit higher contrast adaptation than emmetropic children. This study aimed to determine whether contrast adaptation varies with the type of text viewed by emmetropic and myopic young adults. Baseline contrast sensitivity was determined in 25 emmetropic and 25 spectacle-corrected myopic young adults for 0.5, 1.2, 2.7, 4.4, and 6.2 cycles per degree (cpd) horizontal sine wave gratings. The adults spent periods looking at a 6.2 cpd high-contrast horizontal grating and reading lines of English and Chinese text (these texts comprised 1.2 cpd row and 6 cpd stroke frequencies). The effects of these near tasks on contrast sensitivity were determined, with decreases in sensitivity indicating contrast adaptation. Contrast adaptation was affected by the near task (F2,672 = 43.0 P < 0.001). Adaptation was greater for the grating task (0.13 ± 0.17 log unit, averaged across all frequencies) than reading tasks, but there was no significant difference between the two reading tasks (English 0.05 ± 0.13 log unit versus Chinese 0.04 ± 0.13 log unit). The myopic group showed significantly greater adaptation (by 0.04, 0.04, and 0.05 log units for English, Chinese, and grating tasks, respectively) than the emmetropic group (F1,48 = 5.0 P = 0.03). In young adults, reading Chinese text induced similar contrast adaptation as reading English text. Myopes exhibited greater contrast adaptation than emmetropes. Contrast adaptation, independent of text type, might be associated with myopia development.

Problems of Spectacle Wearing Aphakes

Publisher: Informa UK Limited

Date: 11-1983

DOI: 10.1111/J.1444-0938.1983.TB03721.X

Peripheral Monochromatic Aberrations in Young Adult Caucasian and East Asian Eyes.

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2018

DOI: 10.1097/OPX.0000000000001180

Abstract: Myopia prevalence rates differ between racial groups. If the growth of the eye is sensitive to differences in optical input, the difference in spherical aberration between East Asian and Caucasian eyes found in this study may be important in understanding myopia development. The aim of this study was to determine differences in peripheral wavefront aberrations between two racial groups. Wavefront aberrations were measured using a COAS-HD aberrometer across the 42 × 32° central visual field on 37 right eyes of young adults (18 Caucasians, 19 East Asians mean age 21.5 ± 2.4 years). The mean spherical equivalent refraction was −1.94 ± 1.63 diopters (D) with a range of −5.87 to +0.16 D. Effect of race and visual field position on refractions, in idual Zernike aberration coefficients up to the fourth order, higher-order root-mean-square aberration, and total root-mean-square aberration were assessed by repeated-measures analysis of covariance. Caucasians and East Asians had similar relative peripheral myopia across the visual field. All higher-order aberration coefficients were affected by visual field position. Race had no significant effect on any higher-order Zernike coefficient, but the difference in mean vertical coma coefficient C 3 −1 across the visual field (i.e., average of 38 field locations) approached significance, being less positive in Caucasians than in East Asians ( P = .08). When correction was made for the Caucasian group being slightly less myopic than the East Asian group, spherical aberration coefficient C 4 0 was less positive in Caucasians than in East Asians by 0.04 μm ( P = .001). The rates of change of coma coefficients across the field were not affected by race. Caucasians and East Asians had similar relative peripheral myopia, but with less positive spherical aberration coefficient in Caucasians than in East Asians. It remains to be determined whether aberrations have a role in the difference of myopia prevalence rates in different countries.

Third‐order aberrations of pseudophakic eyes

Publisher: Wiley

Date: 04-1989

DOI: 10.1111/J.1475-1313.1989.TB00843.X

Abstract: The aberrations of pseudophakic eyes were analysed by third-order theory assuming thin intraocular lenses. Third-order aberrations with spherical surfaced lenses are quadratic functions of lens shape. Spherical aberration and coma are generally the most rapidly changing aberrations, at small field positions, with change in lens shape. Optimum designs probably lie within the shape factor range at which these attain minimum absolute values (+1.1, spherical aberration -0.9 to -3.4, coma). The importance of spherical aberration declines relative to that of off-axis aberrations as pupil size decreases. The introduction of a level of corneal asphericity alters each aberration by a constant amount for any lens shape.

Retinal shadows produced by myopia control spectacles

Publisher: Wiley

Date: 29-08-2023

DOI: 10.1111/OPO.13228

Abstract: To analyse ocular coherence tomography (OCT) images of the retinal shadows caused by defocus and diffusion optics spectacles. One eye was fitted successively with the Hoya Defocus Incorporated Multiple Segments (DIMS) spectacle lens, two variations of the +3.50 D peripheral add spectacle (DEFOCUS) and the low‐contrast dot lens (Diffusion Optics Multiple Segments, DOMS) each at a vertex distance of 12 mm. Simultaneously, a retinal image of the macular region with central fixation was obtained using infrared OCT. The corneal power and intraocular distances were determined using an optical biometer. The retinal images for the DIMS and DOMS lenses showed patterns of obvious retinal shadows in the periphery, while the central 10–11° remained clear. The DEFOCUS lens produced a darkened peripheral area. Dividing the size of the retinal pattern, measured with the calliper of the OCT software, by the actual size on the spectacle lens gave a magnification of 0.57 times. Based on the ocular biometry, the magnification of the retinal patterns was estimated at 0.46 times, meaning that the shadows in the OCT images were slightly further away from the fovea than where the wearer would observe them. The source of this discrepancy was probably the angle of the scanning OCT beam, which was not parallel to the optical axis. With device‐specific correction, retinal OCT images can help visualise the regions affected by the defocus or lowered contrast induced by myopia control spectacles. This is of potential value for improving myopia therapies.

The Skew Ray Issue in Ocular Aberration Measurement

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 06-2006

DOI: 10.1097/01.OPX.0000221400.07293.EE

Defocused contrast sensitivity function in peripheral vision.

Publisher: Wiley

Date: 12-12-2022

DOI: 10.1111/OPO.12932

Abstract: Human peripheral detection performance is affected by optical factors such as defocus and higher order aberrations. From optical theory, we would expect defocus to produce local depressions (notches) in the contrast sensitivity function (CSF). However, such notches have not been observed in peripheral vision, and it is unknown whether human peripheral vision can detect local depressions (notches) in the CSF, such as those produced by monochromatic defocus when all monochromatic ocular aberrations are corrected. The purpose of the study was to identify such notches. Participants were three adult emmetropes. Following full adaptive optics correction, on-axis and 20° nasal visual field detection CSFs in monochromatic light were measured for the right eye with a 7 mm diameter pupil, both without and with ±2 D defocus, and with separate determinations for horizontal and vertical gratings. Defocused CSFs were compared with predictions based on theoretical modulation transfer functions. Notches in the monochromatic defocused CSFs were identified for peripheral vision at optically predicted spatial frequencies with other monochromatic ocular aberrations corrected, provided that there was adequate spatial frequency s ling. The spatial frequencies of notches were similar to those predicted from optical theory, but their depths (0.3 to 0.9 log unit) were smaller than predicted. With fine spatial frequency s ling, notches were identified in defocused monochromatic CSFs when all other monochromatic ocular aberrations were corrected, both on-axis and at 20° eccentricity. Unless recognised as such, notches may contribute to noise in through-focus detection measurements of peripheral visual performance.

Lighting for color vision examination in the era of LEDs: the FM100Hue Test

Publisher: Optica Publishing Group

Date: 12-03-2020

DOI: 10.1364/JOSAA.382301

Abstract: Lighting conditions nominated for color vision testing are many and varied. The recommendation of CIE color rendering index (CIE CRI) ≥ 90 and correlated color temperature of close to 6500 K is widely made for color vision testing generally. With the demise of incandescent and fluorescent lighting and their replacement by light-emitting diodes (LEDs), this is an opportune time to revisit the recommendation. In this paper, we consider the current sources, acceptable and unacceptable, and improvements to the recommendation as it applies to the Farnsworth–Munsell 100 Hue Test (FM100Hue Test). We conclude that there is no need to treat LEDs as a special case but propose a modified CRI measure.

Prismatic Effects of Spherical Ophthalmic Lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-1980

DOI: 10.1097/00006324-198011000-00001

Abstract: Exact prismatic effects were calculated for stock spectacle lenses (-6 D to +10 D) and trial refracting set lenses (-10 D to +10 D) using a range of visual field eccentricities on the 0.30 m Goldmann perimeter, and on the 1- and 2-m tangent screens. Slightly larger prismatic effects were found for the tangent screens than the perimeter, but the difference in results for the two tangent screen distances was negligible. For low power ophthalmic lenses (-2 D +2 D), the prismatic effects were smaller than the variation in apparent target eccentricity caused by variation in patient fixation distance. Paraxial estimates of prismatic effects using both thick and thin lens theory were calculated, but found to become more inaccurate as target eccentricity increased. Data are presented which can be used by clinicians to predict the alteration in the size of kinetic perimetric isopters when ophthalmic lenses are used to correct patient defocus resulting from ametropia or presbyopia.

Alternate Forms of Justice and Adjudicating Trauma in 13 Reasons Why

Publisher: Informa UK Limited

Date: 03-07-2022

DOI: 10.1080/13200968.2022.2153491

Peripheral refraction along the horizontal and vertical visual fields in myopia

Publisher: Elsevier BV

Date: 04-2006

DOI: 10.1016/J.VISRES.2005.10.023

Abstract: Peripheral refractions were measured to 35 degrees eccentricity using a free-space autorefractor in young adult emmetropic and myopic subjects. Refractions were measured along horizontal and vertical visual fields for 116 subjects and a 43 subject subset, respectively. Along the horizontal visual field, peripheral myopic shifts in spherical equivalent M of emmetropes changed to relative hypermetropic shifts in the myopes, there were temporal-nasal asymmetries of 90 degrees to 180 degrees astigmatism J(180) which decreased as myopia increased, and 45 degrees to 135 degrees astigmatism J(45) was linearly related to field angle. Along the vertical visual field, both peripheral myopic shifts in peripheral M and J(180) asymmetry were unaffected by magnitude of myopia, and J(45) changed at three times the rate as for the horizontal visual field. Myopia has more effect on peripheral refraction of adult eyes along the horizontal than along the vertical visual field. The peripheral variations in refraction match well what is known about the shapes of emmetropic and myopic eyes.

Case Report — Fundus Flavimaculatus

Publisher: Informa UK Limited

Date: 07-1987

DOI: 10.1111/J.1444-0938.1987.TB04226.X

Paraxial schematic eye models for 7- and 14-year-old Chinese children

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 03-06-2015

DOI: 10.1167/IOVS.15-16428

Abstract: To develop three-surface paraxial schematic eyes with different ages and sexes based on data for 7- and 14-year-old Chinese children from the Anyang Childhood Eye Study. Six sets of paraxial schematic eyes, including 7-year-old eyes, 7-year-old male eyes, 7-year-old female eyes, 14-year-old eyes, 14-year-old male eyes, and 14-year-old female eyes, were developed. Both refraction-dependent and emmetropic eye models were developed, with the former using linear dependence of ocular parameters on refraction. A total of 2059 grade 1 children (boys 58%) and 1536 grade 8 children (boys 49%) were included, with mean age of 7.1 ± 0.4 and 13.7 ± 0.5 years, respectively. Changes in these schematic eyes with aging are increased anterior chamber depth, decreased lens thickness, increased vitreous chamber depth, increased axial length, and decreased lens equivalent power. Male schematic eyes have deeper anterior chamber depth, longer vitreous chamber depth, longer axial length, and lower lens equivalent power than female schematic eyes. Changes in the schematic eyes with positive increase in refraction are decreased anterior chamber depth, increased lens thickness, decreased vitreous chamber depth, decreased axial length, increased corneal radius of curvature, and increased lens power. In general, the emmetropic schematic eyes have biometric parameters similar to those arising from regression fits for the refraction-dependent schematic eyes. The paraxial schematic eyes of Chinese children may be useful for myopia research and for facilitating comparison with other children with the same or different racial backgrounds and living in different places.

The use of autorefractors using the image-size principle in determining on-axis and off-axis refraction. Part 2: Theoretical study of peripheral refraction with the Grand Seiko AutoRef/Keratometer WAM-5500.

Publisher: Wiley

Date: 20-12-2022

DOI: 10.1111/OPO.12936

Abstract: To determine, through simulations, the likely validity of Grand-Seiko autorefractors with annular targets in peripheral refraction. Using a physical model eye, the distance inside the eye to which the Grand Seiko AutoRef/Keratometer WAM-5500 beam was converging and the effective size of its outer diameter at the cornea were determined. Grand-Seiko refraction was calculated from R The instrument beam was determined to be converging towards the eye to a distance of 24.4 mm behind the corneal vertex, with a 2.46 mm effective size outer diameter of the beam at the anterior cornea. The Grand-Seiko refractions provided accurate estimates of peripheral refraction for the model eyes. The results were closer to Zernike refractions than to Zernike paraxial refraction. Spherical aberration influenced refraction by up to 0.5 D, and peripheral coma had limited influence. Grand-Seiko autorefractors in current use, and having a circular annulus with an ingoing effective outer diameter at the front of the eye of about 2.4 mm, are likely to give valid peripheral refractions.

The use of autorefractors using the image-size principle in determining on-axis and off-axis refraction. Part 1: Analysis of optical principles of autorefractors.

Publisher: Wiley

Date: 20-12-2022

DOI: 10.1111/OPO.12933

Abstract: To study the optical principles and properties of autorefractors that use the image-size principle in which the size of the reimaged retinal image determines refraction. The retinal illumination and reimaging of the retinal image were described, as were variations in the basic system. Imaging was determined for systems in which the light source is either erging or converging as it passes into the eye. Equations were determined to describe the dependence of refraction on the heights and angles of incoming and outgoing beams, and refraction error was determined when eye position was not correct. The fundamental refraction equation is For image-size principle autorefractors, simple equations describe the dependence of measured refraction on the height and angle of the instrument beam as it enters the eye and the angle of the light, reflected back from the retina, after it exits the eye. Further work will investigate the validity of such instruments for determining peripheral refraction.

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

Publisher: Springer Science and Business Media LLC

Date: 28-09-2020

DOI: 10.1007/S41114-020-00026-9

Abstract: We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star–black hole, and binary black hole systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. During O3, the median localization volume (90% credible region) is expected to be on the order of $$10^{5}, 10^{6}, 10^{7}\\mathrm {\\ Mpc}^3$$ 10 5 , 10 6 , 10 7 Mpc 3 for binary neutron star, neutron star–black hole, and binary black hole systems, respectively. The localization volume in O4 is expected to be about a factor two smaller than in O3. We predict a detection count of $$1^{+12}_{-1}$$ 1 - 1 + 12 ( $$10^{+52}_{-10}$$ 10 - 10 + 52 ) for binary neutron star mergers, of $$0^{+19}_{-0}$$ 0 - 0 + 19 ( $$1^{+91}_{-1}$$ 1 - 1 + 91 ) for neutron star–black hole mergers, and $$17^{+22}_{-11}$$ 17 - 11 + 22 ( $$79^{+89}_{-44}$$ 79 - 44 + 89 ) for binary black hole mergers in a one-calendar-year observing run of the HLV network during O3 (HLVK network during O4). We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers.

A Yellow Filter Improves Response Times to Low-Contrast Targets and Traffic Hazards

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2013

DOI: 10.1097/OPX.0B013E3182815783

Re: On the mechanism of the eye

Publisher: Informa UK Limited

Date: 05-2018

DOI: 10.1111/CXO.12675

Subjective measurement of the Stiles-Crawford effect with different field sizes

Publisher: Optica Publishing Group

Date: 16-07-2021

DOI: 10.1364/BOE.427834

Abstract: The Stiles-Crawford effect of the first kind (SCE) is the phenomenon in which light entering the eye near the center of the pupil appears brighter than light entering near the edge. Previous investigations have found an increase in the directionality (steepness) of the effect as the testing location moves from the center of the visual field to parafoveal positions, but the effect of central field size has not been considered. The influence of field size on the SCE was investigated using a uniaxial Maxwellian system in which stimulus presentation was controlled by an active-matrix liquid crystal display. SCE directionality increased as field size increased from 0.5° to 4.7° diameter, although this was noted in four mild myopes and not in two emmetropes. The change with field size was supported by a geometric optics absorption model.

Analysis of higher-order aberrations in a large clinical population

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 29-11-2012

DOI: 10.1167/IOVS.12-10610

Abstract: To use a large wave-front database of a clinical population to investigate relationships between refractions and higher-order aberrations and between aberrations of right and left eyes. Third- and fourth-order aberration coefficients and higher-order root-mean-squared aberrations (HO RMS), scaled to a pupil size of 4.5-mm diameter, were analyzed in a population of approximately 24,000 patients from Carl Zeiss Vision's European wave-front database. Correlations were determined between the aberrations and the variables of refraction, near addition, and cylinder. Most aberration coefficients were significantly dependent upon these variables, but the proportion of aberrations that could be explained by these factors was less than 2% except for spherical aberration (12%), horizontal coma (9%), and HO RMS (7%). Near addition was the major contributor for horizontal coma (8.5% out of 9.5%) and spherical equivalent was the major contributor for spherical aberration (7.7% out of 11.6%). Interocular correlations were highly significant for all aberration coefficients, varying between 0.16 and 0.81. Anisometropia was a variable of significance for three aberrations (vertical coma, secondary astigmatism, and tetrafoil), but little importance can be placed on this finding because of the small proportion of aberrations that can be explained by refraction (all <1.0%). Most third- and fourth-order aberration coefficients were significantly dependent upon spherical equivalent, near addition, and cylinder, but only horizontal coma (9%) and spherical aberration (12%) showed dependencies greater than 2%. Interocular correlations were highly significant for all aberration coefficients, but anisometropia had little influence on aberration coefficients.

Recent advances in representation of monochromatic aberrations of human eyes

Publisher: Informa UK Limited

Date: 05-2004

DOI: 10.1111/J.1444-0938.2004.TB03166.X

Abstract: The field of aberrations of the human eye is moving rapidly, being driven by the desire to monitor and optimise vision following refractive surgery. In this paper, I discuss the different ways of representing aberrations of the human eye, the terminology used, how wave aberrations are used to determine refractions, the influence of pupil size on aberrations, how to compare right and left eye aberrations, how aberrations can be manipulated into different forms, how to make corrections for changes in wavelength, the appropriate ocular axis, and corneal and lenticular components of the aberrations.

Measuring ocular aberrations in the peripheral visual field using Hartmann-Shack aberrometry

Publisher: Optica Publishing Group

Date: 2007

DOI: 10.1364/JOSAA.24.002963

Abstract: We have used the Hartmann-Shack technique previously to measure ocular aberrations along the horizontal meridian of the visual field. This requires considerable modifications from the technique for measuring the aberrations corresponding to the fovea. We now further develop the technique so that it can be used for any meridian of the visual field. Allowance is made for any auxiliary optics placed in front of the eye to compensate for the limited range of the Hartmann-Shack technique and for the case where aberrations are estimated at a wavelength other than the measuring wavelength. Zernike wave aberrations are converted to peripheral refractions. Ex les are presented showing the developments, and we discuss change in wave aberrations when converting from a circular to an elliptical pupil.

Effect of defocus on on-axis wave aberration of a centered optical system

Publisher: Optica Publishing Group

Date: 11-2006

DOI: 10.1364/JOSAA.23.002686

Abstract: We derive equations for defocus and primary spherical wave aberration coefficients caused by a shift in image plane of a perfect optical system. The spherical aberration equation is accurate at describing changes in the spherical aberration of an aberrated schematic eye.

Through-focus performance with multifocal contact lenses: Effect of binocularity, pupil diameter and inherent ocular aberrations

Publisher: Wiley

Date: 12-2013

DOI: 10.1111/OPO.12004

Abstract: To evaluate the effects of the wearer's pupil size and spherical aberration on visual performance with centre-near, aspheric multifocal contact lenses (MFCLs). The advantage of binocular over monocular vision was also investigated. Twelve young volunteers, with an average age of 27 ± 5 years, participated in the study. LogMAR Visual Acuity (VA) was measured under cycloplegia for a range of defocus levels (from +3.0 to -3.0 D, in 0.5 D steps) with no correction and with three aspheric MFCLs (Air Optix Aqua Multifocal) with a centre-near design, providing correction for 'Low', 'Med' and 'High' near demands. Measurements were performed for all combinations of the following conditions: (1) artificial pupils of 6 and 3 mm diameter, (2) binocular and monocular (dominant eye) vision. Depth-of-focus (DOF) was calculated from the VA vs defocus curves. Ocular aberrations under cycloplegia were measured using iTrace. VA at -3.0 D defocus (simulating near performance) was statistically higher for the 3 mm than for the 6 mm pupil (p = 0.006), and for binocular rather than for monocular vision (p < 0.001). Similarly, DOF was better for the 3 mm pupil (p = 0.002) and for binocular viewing conditions (p < 0.001). Both VA at -3.0 D defocus and DOF increased as the 'addition' of the MFCL correction increased. Finally, with the centre-near MFCLs a linear correlation was found between VA at -3.0 D defocus and the wearer's ocular spherical aberration (R(2) = 0.20 p < 0.001 for 6 mm data), with the eyes exhibiting the higher positive spherical aberration experiencing worse VAs. By contrast, no correlation was found between VA and spherical aberration at 0.00 D defocus (distance vision). Both near VA and depth-of-focus improve with these MFCLs, with the effects being more pronounced for small pupils and for binocular rather than monocular vision. Coupling of the wearer's ocular spherical aberration with the aberration profiles provided by MFCLs affects their functionality.

Theoretical Effect of Refractive Error and Accommodation on Longitudinal Chromatic Aberration of the Human Eye

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-1993

DOI: 10.1097/00006324-199309000-00006

Abstract: Simple formulas based on reduced eyes have been developed to predict the variation in longitudinal chromatic aberration with variation in ametropia or accommodation. Two formulas were developed, one for axial ametropia and one for refractive ametropia. The latter also served as a model for accommodation. The results using the formulas are in close agreement with results obtained using raytracing through more sophisticated models. Combining the results of different methods gives the following predictions of change in chromatic difference of focus, between wavelengths of 400 and 700 nm, with change in each diopter of refractive error or accommodation: axial ametropia 0.012 to 0.017 D (0.6 to 0.9%), refractive ametropia 0.05 D (2.2 to 2.4%), and accommodation 0.04 to 0.05 D (2.1 to 2.6%). The chromatic aberration effects of correcting lenses with low dispersion are intermediate in effect and opposite in sign to the effects of corresponding degrees of axial ametropia and refractive ametropia.

Limits of spherical blur determined with an adaptive optics mirror

Publisher: Wiley

Date: 15-04-2009

DOI: 10.1111/J.1475-1313.2009.00637.X

Abstract: We extended an earlier study (Vision Research, 45, 1967-1974, 2005) in which we investigated limits at which induced blur of letter targets becomes noticeable, troublesome and objectionable. Here we used a deformable adaptive optics mirror to vary spherical defocus for conditions of a white background with correction of astigmatism a white background with reduction of all aberrations other than defocus and a monochromatic background with reduction of all aberrations other than defocus. We used seven cyclopleged subjects, lines of three high-contrast letters as targets, 3-6 mm artificial pupils, and 0.1-0.6 logMAR letter sizes. Subjects used a method of adjustment to control the defocus component of the mirror to set the 'just noticeable', 'just troublesome' and 'just objectionable' defocus levels. For the white-no adaptive optics condition combined with 0.1 logMAR letter size, mean 'noticeable' blur limits were +/-0.30, +/-0.24 and +/-0.23 D at 3, 4 and 6 mm pupils, respectively. White-adaptive optics and monochromatic-adaptive optics conditions reduced blur limits by 8% and 20%, respectively. Increasing pupil size from 3-6 mm decreased blur limits by 29%, and increasing letter size increased blur limits by 79%. Ratios of troublesome to noticeable, and of objectionable to noticeable, blur limits were 1.9 and 2.7 times, respectively. The study shows that the deformable mirror can be used to vary defocus in vision experiments. Overall, the results of noticeable, troublesome and objectionable blur agreed well with those of the previous study. Attempting to reduce higher-order aberrations or chromatic aberrations, reduced blur limits to only a small extent.

Glare-free retinal imaging using a portable light field fundus camera

Publisher: The Optical Society

Date: 20-06-2018

DOI: 10.1364/BOE.9.003178

The effect of scleral lenses on vision, refraction and aberrations in post‐LASIK ectasia, keratoconus and pellucid marginal degeneration

Publisher: Wiley

Date: 26-03-2021

DOI: 10.1111/OPO.12802

Abstract: To quantify the effect of a single scleral lens design on visual acuity and ocular higher‐order aberrations in eyes with post–LASIK ectasia, keratoconus and pellucid marginal degeneration (PMD) that could not achieve satisfactory vision with spectacles or soft contact lenses. Forty‐six eyes of 28 participants fitted with diagnostic scleral lenses (KeraCare) were analysed, including 19, 15 and 12 eyes with post‐LASIK ectasia, keratoconus and PMD, respectively. Corrected distance visual acuity (CDVA) and ocular aberrations were measured prior to lens wear and during lens wear after 60 min of settling. An i–Trace aberrometer was used to determine aberrations over a 4.5 mm diameter pupil. Before lens wear, the median (95% confidence interval) values across all groups were: CDVA 0.30 (0.30, 0.40) logMAR, spherical equivalent refraction –2.75 (–5.25, –2.12) D, cylindrical refraction 3.75 (2.50, 5.00) D, higher–order–root–mean–square error (HO‐RMS) 0.90 (0.64, 1.03) μm and vertical coma co‐efficient C(3,–1) –0.32 (–0.42, –0.12) μm. RMS coma of 0.52 (0.40, 0.74) μm was higher for the keratoconus group than for the other groups ( p 0.05). During lens wear, values improved considerably across all groups: CDVA 0.0 (0.0, 0.00) logMAR, spherical equivalent refraction –0.50 (–0.75, +0.50) D, cylindrical refraction 0.50 (0.00, 0.50) D, HO‐RMS 0.32 (0.26, 0.42) μm and C(3,–1) +0.12 (+0.02, +0.19) μm (all p 0.001 compared to pre‐lens wear). While reduced significantly, RMS coma remained higher in the keratoconus group at 0.35 (0.31, 0.52) μm than in the post–LASIK ectasia and PMD groups at 0.17 (0.12, 0.21) μm and 0.07 (0.02, 0.46) μm, respectively ( p 0.05). The KeraCare scleral contact lens reduced ocular aberrations and improved visual acuity in patients with post–LASIK ectasia, keratoconus and PMD. The sign of vertical coma changed in keratoconus and PMD.

Improvements to phakometry through use of bessel beams

Publisher: OSA

Date: 2016

DOI: 10.1364/AOMS.2016.AOM3C.5

Use of the Humphrey Lens Analyzer for Off-Axis Measurements of Spectacle Lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-1991

DOI: 10.1097/00006324-199104000-00007

Abstract: Automated focimeters can be used to make quick, precise measurements of off-axis power and prismatic effects corresponding to an eye rotating behind a spectacle lens. An automated focimeter, the Humphrey Lens Analyzer, was assessed in this regard. The Humphrey Lens Analyzer can be used to give a valid measure of off-axis power of lenses with low power, but not of lenses with moderate to higher power (greater than 3 D). For 3 D spherical lenses discrepancies of the order of 0.1 D occur at 30 degrees rotation, and 6 D spheres give discrepancies of 0.5 D at the same rotation. Small discrepancies were found for measurements of prism. The Humphrey Lens Analyzer was also used in a mode where the lens being tested is rotated about the center of curvature of its back surface. This is the mode often used to assess aberrations and prism of progressive-addition lenses. In this mode, the instrument provides reasonable accuracy in estimating off-axis power corresponding to eye rotation for lenses with low power, but not for lenses with moderate to higher power (greater than 3 D). However, it provides accurate values of the variation in off-axis surface power for low powered lenses with aspheric front surfaces. There were considerable systematic errors associated with the measurement of prism. A simple raytracing method was developed to predict the results of measurements with the Humphrey Lens Analyzer. Predictions of off-axis power were good when lenses were rotated about a position corresponding to the center-of-rotation of an eye, but were poorer when lenses were rotated about the center of curvature of their back surfaces. Predictions of primatic efforts were good in both situations. A method by which the Humphrey Lens Analyzer should provide an accurate measurement of off-axis powers corresponding to eye rotation behind a spectacle lens is described, but has not been tested.

Nonlinear characterization of a simple process in human vision

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 11-2009

DOI: 10.1167/9.12.1

Contrast sensitivity and the Stiles–Crawford effect

Publisher: Elsevier BV

Date: 06-2002

DOI: 10.1016/S0042-6989(02)00084-6

Abstract: We investigated the influence of the Stiles-Crawford effect (SCE) of the first kind on the contrast sensitivity function using the apodisation model of the SCE. The SCE was measured for the right eyes of two subjects using an increment threshold technique involving a two-channel Maxwellian-viewing system. Filters made of photographic film neutralised or doubled the SCE. Contrast sensitivities were measured with a 6 mm pupil diameter, defocus to +/-2D, and three SCE conditions (normal, neutralised and doubled). Modulation transfer functions were derived after measuring transverse aberrations with a vernier alignment technique, and were used to predict contrast sensitivity functions (CSFs). The measured CSFs were, in general, reasonable matches with the predicted CSFs. In particular, both demonstrated definite undulations ("notches") as defocus level increased. The influences of the SCE-modifying filters were generally of similar magnitude and direction to predictions, thus supporting the apodisation model of the SCE. The magnitudes of SCE influence between SCE-neutralised and SCE-doubled conditions were usually small at about 0.2-0.3 log unit, with a maximum influence of 0.5 log unit. Influences of the SCE were greater for myopic than for hypermetropic defocus. As measured by the CSF and an apodisation model, this study is in agreement with previous theoretical work and one experimental study in indicating that the SCE plays a minor role in improving spatial visual performance.

Chromatic Aberration and Optical Power of a Diffractive Bifocal Contact Lens

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 10-1992

DOI: 10.1097/00006324-199210000-00009

Abstract: Although diffractive contact lenses have been well documented in theory, no definitive experimental data have been reported which confirm that the near image is in fact created by diffraction rather than by refraction. We have tested the diffraction hypothesis for one type of diffractive contact lens (the Hydron Echelon bifocal) experimentally by measuring its longitudinal chromatic aberration in isolation and when worn on the eye. The basis of this test is that, according to theory, diffractive lenses should have chromatic aberration which is opposite in sign to that measured for the eye. Objective measurements of chromatic aberration were made with a focimeter when the lens was in a wet cell. Subjective measurements were made with a Badal optometer when the lens was worn on the eye. Four control experiments were conducted to provide baseline measurements of the eye's chromatic aberration, against which we compared the results obtained for the diffractive contact lens. The data were also compared with conventional measurements of refractive error obtained by standard subjective techniques and by an automated infrared refractor. Our results showed that the longitudinal chromatic aberration of the diffraction image of the Echelon bifocal lens was about one-half that obtained under the four control conditions: for the naked eye, for the nondiffraction image of the Echelon lens, or for either image of a refractive bifocal contact lens (CIBA Bisoft). These results are consistent with the theoretical prediction that the negative chromatic aberration of a diffractive contact lens should partially cancel the positive chromatic aberration of the human eye.(ABSTRACT TRUNCATED AT 250 WORDS)

Spectacle lens design: a review

Publisher: Optica Publishing Group

Date: 07-1992

DOI: 10.1364/AO.31.003579

Aberrations and Pupil Location under Corneal Topography and Hartmann-Shack Illumination Conditions

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 04-2009

DOI: 10.1167/IOVS.08-2111

Abstract: This study was conducted to determine the magnitude of pupil center shift between the illumination conditions provided by corneal topography measurement (photopic illuminance) and by Hartmann-Shack aberrometry (mesopic illuminance) and to investigate the importance of this shift when calculating corneal aberrations and for the success of wavefront-guided surgical procedures. Sixty-two subjects with emmetropia underwent corneal topography and Hartmann-Shack aberrometry. Corneal limbus and pupil edges were detected, and the differences between their respective centers were determined for both procedures. Corneal aberrations were calculated using the pupil centers for corneal topography and for Hartmann-Shack aberrometry. Bland-Altmann plots and paired t-tests were used to analyze the differences between corneal aberrations referenced to the two pupil centers. The mean magnitude (modulus) of the displacement of the pupil with the change of the illumination conditions was 0.21+/-0.11 mm. The effect of this pupillary shift was manifest for coma corneal aberrations for 5-mm pupils, but the two sets of aberrations calculated with the two pupil positions were not significantly different. Sixty-eight percent of the population had differences in coma smaller than 0.05 microm, and only 4% had differences larger than 0.1 microm. Pupil displacement was not large enough to significantly affect other higher-order Zernike modes. Estimated corneal aberrations changed slightly between photopic and mesopic illumination conditions given by corneal topography and Hartmann-Shack aberrometry. However, this systematic pupil shift, according to the published tolerances ranges, is enough to deteriorate the optical quality below the theoretically predicted diffraction limit of wavefront-guided corneal surgery.

Differences in retinal shape between East Asian and Caucasian eyes.

Publisher: Wiley

Date: 29-03-2017

DOI: 10.1111/OPO.12359

Abstract: To investigate whether retinal shape is different between East Asians and Caucasians. There were 36 East Asian and 40 Caucasian young adults, with refractions between +0.75D and −5.50D. Peripheral eye lengths were obtained after pupil dilation using the Lenstar partial coherence interferometer. Measurements were obtained along the horizontal and vertical meridians of the visual field out to ±35° and ±30°, respectively, in 5° steps. Retinal co‐ordinates were estimated using a validated method from the peripheral eye length measurements and ray‐tracing through a modified Le Grand full theoretical eye. Rays were directed normally towards the anterior cornea. Retinal shapes were described in terms of vertex radius of curvature ( R v ), asphericity ( Q ) and equivalent radius of curvature ( R E q ) along both horizontal and vertical meridians. R v was smaller in East Asian than in Caucasians (mean difference ± 95% CI −0.7 ± 0.5 mm), along the horizontal meridian than the vertical meridian (−1.2 ± 0.6 mm), and in myopia than in emmetropia (−1.0 ± 0.6 mm). R v along the horizontal meridian, but not along the vertical meridian, became smaller as myopia increased. Q did not vary significantly with meridian, refraction group or race. The same pattern of results occurred for R E q as for R v . The percentage differences of heights under the estimated retinal surfaces showed steeper retinas in East Asians than in Caucasians the differences between East Asian and Caucasian emmetropes were 2.5% and % along horizontal and vertical meridians, respectively, and corresponding differences for myopes were 4.6% and 1.8%. East Asians had steeper retinas than Caucasians. The horizontal meridian had steeper retinas than the vertical meridian. Myopes had steeper retinas than emmetropes. Racial differences in retinal shape in both emmetropes and myopes, combined with the high prevalence of myopia in East Asia, suggest that retinal shape may play a role in myopia development.

Peripheral aberrations in adult hyperopes, emmetropes and myopes

Publisher: Wiley

Date: 17-02-2017

DOI: 10.1111/OPO.12354

Abstract: To determine differences in peripheral aberrations in hyperopic, emmetropic and myopic groups. Cycloplegic peripheral aberrations for 5 mm pupils were measured at 39 locations across 42° × 32° of right eye visual fields with a COAS ‐ HD Hartmann‐Shack aberrometer in nine hyperopes (mean age 29 ± 5 years, spherical equivalent refraction M + 1.47 ± 0.58 D), 20 emmetropes (28 ± 7 years, +0.06 ± 0.36 D) and 20 myopes (27 ± 6 years, −2.55 ± 1.82 D). Relative peripheral refraction error RPRE and 3rd–4th order Zernike coefficients were compared between the groups. Hyperopes and emmetropes had relative peripheral myopia across the visual field, with considerable nasal‐temporal asymmetry for both groups and superior‐inferior asymmetry for hyperopes. Myopes had minimal RPRE along the horizontal meridian, but myopic RPRE along the vertical meridian which was less than the other groups. There was little difference between groups in astigmatic components or higher‐order Zernike coefficients, except for fourth‐order spherical aberration which was more positive in hyperopes than in both emmetropes (mean difference ±95% CI = +0.05 ± 0.05 μm, p = 0.03) and myopes (+0.07 ± 0.04 μm, p = 0.003). Coma changed rapidly across the visual field with similar rates for all groups. Hyperopes and emmetropes had greater relative peripheral myopia than myopes. There was asymmetry in RPRE along the vertical meridian for hyperopes which was not present in the emmetropes, suggesting there may be asymmetries in peripheral eye length along the vertical meridian for the former. Higher‐order aberrations were affected by field eccentricity, but refractive error affected only the spherical aberration coefficient, which was more positive for hyperopes than for other groups.

Theoretical analysis of peripheral imaging after excimer laser corneal refractive surgery for myopia

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-2002

DOI: 10.1016/S0886-3350(02)01539-0

Letter to the editor

Publisher: Informa UK Limited

Date: 08-2013

DOI: 10.2147/OPTH.S50107

SPECTACLE LENSES AND THIRD‐ORDER DISTORTION

Publisher: Wiley

Date: 07-1987

DOI: 10.1111/J.1475-1313.1987.TB00747.X

Straylight, lens yellowing and aberrations of eyes in type 1 diabetes

Publisher: The Optical Society

Date: 13-03-2015

DOI: 10.1364/BOE.6.001282

Children's accommodation during reading of Chinese and English texts

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 02-2013

DOI: 10.1097/OPX.0B013E31827CE23A

Effect of accommodation on peripheral eye lengths of emmetropes and myopes

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2017

DOI: 10.1097/OPX.0000000000001037

Abstract: To investigate the effect of accommodation on central and peripheral axial lengths in young adult emmetropes and myopes. On-axis and peripheral axial lengths were measured with the Haag-Streit Lenstar in 83 young adult participants for 0D and 6D accommodation demands. A Badal system was used to both correct refractive errors and induce accommodation. Participants were emmetropes ( n = 29, mean spherical equivalent refraction +0.35 ± 0.35D), low myopes (32, −1.38 ± 0.73D), and higher myopes (22, −4.30 ± 0.73D). Ages were similar for all groups (22 ± 2 years). Pupils were dilated with 2.5% phenylephrine to allow a large field of measurement while maintaining active accommodation. Axial lengths were measured in 5° steps to ±30° across the horizontal visual field. With accommodation, axial length increased for all refractive groups at all positions, but with lessening effect away from fixation. Axial length changes were greater for higher myopes than for emmetropes on-axis (higher myopes 41 ± 14 μm, emmetropes 30 ± 12 μm, P = .005), for higher myopes than for low myopes at 30° nasal ( P = .03), and for the higher myopes than for the other groups at 20° nasal ( P .05). There were significant correlations between myopia and changes in axial length at all positions, with the highest correlation on-axis ( R 2 = 0.30, P .001). During accommodation, eye length increased out to at least ±30° visual angle in young adult myopes and emmetropes. The increase was significantly greater for higher myopes than for the other groups at some positions. At all positions, there were significant correlations between myopia and accommodation-induced changes in axial length.

Accommodation stimulus and response determinations with autorefractors

Publisher: Wiley

Date: 28-12-2016

DOI: 10.1111/OPO.12340

Abstract: To develop equations for accommodation stimulus and accommodation response with autorefractors when the accommodation stimulus is produced by combinations of object distances and lenses placed in front of eyes, and to give worked ex les using these equations. Simple ray tracing was used to determine stimulus and response equations, taking into account the reference positions for targets, for refraction, and for autorefractor readings. Several ex les applying equations are provided. Features of these ex les include evaluating approximate calculations that have been used previously, demonstrating which equations should be used in different circumstances, how to substitute numbers into equations, how to deal with discrepancies between subjective and objective refraction, and how to deal with astigmatism. Problems associated with measuring accommodation response by placing lenses in front of the eye are discussed. Accurate equations for accommodation stimulus and accommodation response for a range of accommodation stimuli in different setups have been developed.

Traffic Signal Color Recognition Is a Problem for Both Protan and Deutan Color-Vision Deficients

Publisher: SAGE Publications

Date: 09-2003

DOI: 10.1518/HFES.45.3.495.27247

Abstract: We investigated the effect of color-vision deficiency on reaction times and accuracy of identification of traffic light signals. Participants were 20 color-normal and 49 color-deficient males, the latter ided into subgroups of different severity and type. Participants performed a tracking task. At random intervals, stimuli simulating standard traffic light signals were presented against a white background at 5° to right or left. Participants identified stimulus color (red/yellow/green) by pressing an appropriate response button. Mean response times for color normals were 525, 410, and 450 ms for red, yellow, and green lights, respectively. For color deficients, response times to red lights increased with increase in severity of color deficiency, with deutans performing worse than protans of similar severity: response times of deuteranopes and protanopes were 53% and 35% longer than those of color normals. A similar pattern occurred for yellow lights, with deuteranopes and protanopes having increased response times of 85% and 53%, respectively. For green lights, response times of all groups were similar. Error rates showed patterns similar to those of response times. Contrary to previous studies, deutans performed much worse than protans of similar severity. Actual or potential applications of this research include traffic signal design and driver licensing.

Effects of pupil center shift on ocular aberrations

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 18-09-2014

DOI: 10.1167/IOVS.14-14212

Abstract: We investigated effects of pupil shifts, occurring with changes in luminance and accommodation stimuli, on refraction components and higher-order aberrations. Participants were young and older groups (n = 20 22 ± 2 years age range, 18-25 years and n = 19, 49 ± 4 years, 45-58 years, respectively). Aberrations/refractions at 4- and 3-mm diameters were compared between centered and decentered pupils for low (background, 0.01 cd/m(2), 0 diopters [D]), and high (6100 cd/m(2), 4 or 6 D) stimuli. Decentration was the difference between pupil centers for low and high stimuli. Clinical important changes with decentration were: M at ± 0.50 or ± 0.25 D, J180 and J45 at ± 0.25 or ± 0.125 D, HORMS at ± 0.05 μm, C(3, 1) at ± 0.05 μm, and C(4, 0) at ± 0.05 μm. Because of small pupil shifts in most participants (mean 0.26 mm), there were few important changes in most refraction components and higher-order aberration terms. However, M changed by >0.25 D for a third of participants with 4-mm pupils. When determining refractions from second to sixth order aberration coefficients, the more stringent criteria gave 76/534 (14%) possible important changes. Some participants had large pupil shifts with considerable aberration changes. Comparisons at the high stimulus were possible for only 11 participants because of small pupils. When refractions were determined from second order aberration coefficients only, only 35 (7%) had important changes for the more stringent criteria. Usually pupil shifts with changes in stimulus conditions have little influence on aberrations, but they can with high shifts. The number of aberrations orders that are considered as contributing to refraction influences the proportion of cases that might be considered clinically important.

Critical Subjective Measurement of Amplitude of Accommodation

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-1994

DOI: 10.1097/00006324-199411000-00005

Abstract: The use of fixed print size to measure litude of accommodation by the push-up method will result in a range of angular sizes of the print at the nearpoint for patients with different litudes. We investigated the effect of this on measured litude of accommodation in 60 subjects aged 25 to 45 years. We designed a near-vision chart, based on the Bailey-Lovie near-vision charts, but for which the letter sizes on adjacent lines are varied so that the difference between the inverse of letter sizes is constant (dioptric scale) rather than the geometric ratio between letters on adjacent lines being constant (logarithmic scale). Using this new chart, we compared the litudes obtained using N5 print (N5 Blur method) and with two critical methods for which the print of interest was always close to threshold acuity. This was achieved by having patients' attention drawn to a smaller line of letters every time the chart was moved closer in half-diopter steps. The N5 Blur method gave considerably higher litude measures than the two critical methods, but the mean differences decreased markedly as age increased: 1.8 to 2.2 D for a 25- to 29-year-old group to 0.7 to 0.8 D for a 40- to 45-year-old group. We believe that the use of fixed size print for measuring litude of accommodation by the push-up method gives overestimations that are more marked the higher the litude. This occurs because smaller measuring distances that accompany the higher litudes will increase angular size and consequently depth-of-focus (in dioptric terms).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Surfaced Prism on Spectacle Lens Power

Publisher: Informa UK Limited

Date: 1984

DOI: 10.1111/J.1444-0938.1984.TB02346.X

Code, Nintendo’s Super Mario and Digital Legality

Publisher: Springer Science and Business Media LLC

Date: 20-03-2015

DOI: 10.1007/S11196-015-9417-X

Near work-induced contrast adaptation in emmetropic and myopic children

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 05-06-2012

DOI: 10.1167/IOVS.11-8959

Abstract: Contrast adaptation may induce an error signal for emmetropization. This research aims to determine whether reading causes contrast adaptation in children and, if so, to determine whether myopes exhibit greater contrast adaptation than emmetropes. Baseline contrast sensitivity was determined in 34 emmetropic and 34 spectacle-corrected myopic children for 0.5, 1.2, 2.7, 4.4, and 6.2 cycles per degree (cpd) horizontal sine-wave gratings. Effects of near tasks on contrast sensitivity were determined during periods spent looking at a 6.2 cpd horizontal grating and during periods spent reading lines of English text, with 1.2 cpd row frequency and 6 cpd stroke frequency. Both emmetropic and myopic groups (mean ± SD age, 10.3 ± 1.4 years) showed reduced contrast sensitivity during both near tasks, with greatest overall adaptation at 6.2 cpd. Adaptation induced by viewing the grating (0.15 ± 0.17 log unit [40%] range, 0.07-0.27 log unit) was significantly greater than adaptation induced by reading text (0.11 ± 0.18 log unit [29%], 0.08-0.16 log unit) (F(1,594) = 10.7 P = 0.001). Myopic children showed significantly greater adaptation across the tasks (0.15 ± 0.18 log unit [42%]) than emmetropic children (0.10 ± 0.16 log unit [26%]) (F(1,66) = 7.30 P = 0.009), with the greatest difference occurring at 4.4 cpd (mean, 0.11 log unit [30%]). Grating and reading tasks induced contrast adaptation viewing horizontal gratings induced greater adaptation than reading, and myopes exhibited greater adaptation than emmetropes. Contrast adaptation effects may underlie findings of prolonged near work being associated with myopia. However, our research does not show whether this is consequential or causal.

Influence of spherical intraocular lens implantation and conventional laser in situ keratomileusis on peripheral ocular aberrations

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-2010

DOI: 10.1016/J.JCRS.2010.01.018

Abstract: To measure the effect of spherical intraocular lens (IOL) implantation and conventional myopic laser in situ keratomileusis (LASIK) on peripheral ocular aberrations. Visual and Ophthalmic Optics Laboratory, School of Optometry, and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. Peripheral aberrations were measured using a modified commercial Hartmann-Shack aberrometer across 42 degrees x 32 degrees of the central visual field after spherical IOL implantation and after conventional LASIK for myopia. The results were compared with those in an age-matched emmetropic group and an age-matched myopic control group, respectively. The rate of quadratic change in spherical equivalent (SE) refraction, higher-order root-mean-square (RMS) aberrations, and total RMS aberrations across the visual field was greater and the amount of spherical aberration higher in the IOL group than in the emmetropic control group. However, coma trends were similar in the 2 groups. The rate of quadratic change in SE refraction, higher-order RMS aberrations, and total RMS aberrations was greater across the field and the amount of spherical aberration higher in the LASIK group than in the myopic control group. The trend in coma across the field in the LASIK group was opposite that in the other groups. Spherical IOL implantation and conventional myopic LASIK increased ocular peripheral aberrations, causing a significant increase in spherical aberration across the visual field. Laser in situ keratomileusis reversed the sign of the rate of change in coma across the field relative to that in the other groups. No author has a financial or proprietary interest in any material or method mentioned.

Validation of a partial coherence interferometry method for estimating retinal shape.

Publisher: The Optical Society

Date: 05-08-2015

DOI: 10.1364/BOE.6.003235

The possible role of peripheral refraction in development of myopia

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-2016

DOI: 10.1097/OPX.0000000000000979

Abstract: Recent longitudinal studies do not support the current theory of relative peripheral hyperopia causing myopia. The theory is based on misunderstanding of the Hoogerheide et al. article of 1971, which actually found relative peripheral hyperopia to be present after, rather than before, myopia development. The authors present two alternative theories of the role of peripheral refraction in the development and progression of myopia. The one for which most detail is given is based on cessation of ocular growth when the periphery is at an emmetropic stage as determined by equivalent blur of the two line foci caused by oblique astigmatism. This paper is based on an invited commentary on the role of lens treatments in myopia from the 15th International Myopia Conference in Wenzhou, China in September 2015.

Description of a method for neutralising the Stiles–Crawford effect

Publisher: Wiley

Date: 03-2001

DOI: 10.1046/J.1475-1313.2001.00560.X

Abstract: The influence of the Stiles–Crawford effect on visual performance can be investigated by filters based on the apodisation model of the Stiles–Crawford effect. We describe the development of practical filters to achieve neutralisation. We present some results of the Stiles–Crawford function showing that the filters work well for expected errors in aligning filters in front of the eye.

Diffractive properties of the Diffrax® bifocal contact lens

Publisher: Wiley

Date: 04-1993

DOI: 10.1111/J.1475-1313.1993.TB00451.X

Abstract: We have verified that the Pilkington Diffrax lens behaves optically as a diffractive bifocal contact lens. The longitudinal chromatic aberration of the lens is similar to that predicted by theory, both on and off the eye. The over-refraction with the lens on the eye is similar to the distance subjective refraction, which is also as predicted.

Peripheral detection acuity for interference fringes and screen-based Gabor gratings

Publisher: Optica Publishing Group

Date: 28-11-2022

DOI: 10.1364/BOE.473486

Abstract: This study compared on-axis and peripheral detection acuities measured with interference fringes, that bypass eye optics, and with screen-based Gabor gratings combined with an adaptive optics system. Gabor gratings are sinusoidal gratings incorporated with a Gaussian envelope that attenuate spatial frequency broadening that occur at the window edge. The magnitude of the attenuation was varied. Peripheral detection acuities were always higher for interference fringes than for Gabor gratings. Less attenuated Gabors (with sharper edges) had higher acuities than more attenuated Gabors (with less sharp edges). Theoretical investigations indicated that the spatial frequency broadening occurring due to the sharp edge of the less attenuated Gabors contribute little to high detection grating acuity in the periphery, but that the lower attenuation provides a greater number of visible cycles which is of more benefit to detection than is the case on-axis.

Influence of age on peripheral refraction

Publisher: Elsevier BV

Date: 03-2005

DOI: 10.1016/J.VISRES.2004.09.028

Abstract: To investigate how age affects peripheral refraction we measured objective peripheral refraction for 55 young subjects (24+/-4 years) and 41 older subjects (59+/-3 years) out to 35 degrees eccentricity in temporal and nasal visual fields. Subjects were compared in 1D subgroups based on central spherical equivalent refractions (low hypermetropes +0.54 D to +1.51 D, emmetropes +0.50 D to -0.49 D, low myopes -0.50 D to -1.49 D, moderate myopes -1.50 D to -2.58 D). Overall, young and older subjects with similar refractive corrections had similar peripheral refraction components. Both age groups showed relative hypermetropic shifts in the peripheral fields as myopia increased and also decreases in peripheral astigmatism J180 as myopia increased. J45 varied little across the visual field with linear relationships occurring between J45 and visual field angle for all but one subgroup (older emmetropes). Peripheral refraction in emmetropes to moderate myopes is relatively unaffected by age for healthy eyes of similar refractive errors.

Visual acuity, contrast sensitivity, and phase transfer function depend on the Stiles Crawford peak location

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 12-2002

DOI: 10.1167/2.10.119

Small-aperture optics for the presbyope: do comparable designs of corneal inlays and intraocular lenses provide similar transmittances to the retina?

Publisher: The Optical Society

Date: 02-2019

DOI: 10.1364/JOSAA.36.0000B7

The Effect of Vertically Yoked Prisms on Binocular Vision and Accommodation

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 20-05-2019

DOI: 10.1097/OPX.0000000000001388

Abstract: Vertically yoked prisms have been used in treatment of binocular vision dysfunction despite minimal supporting evidence. In people with normal binocular vision, the impact on phorias has been assessed but not the impact on accommodation, accommodation vergence interactions, or the horopter. We found that vertically yoked prisms have minor effects during short-term wear in young adults. The purpose of this study was to determine effects of vertically yoked prisms on accommodative response and several binocular vision tasks. There were 45 participants aged 18 to 24 years. The 23 myopes wore distance-corrected soft contact lenses. In a random arrangement, each person wore spectacles containing planopower lenses with either 8 Δ base-up, 4 Δ base-up, zero, 4 Δ base-down, and 8 Δ base-down prisms. Before spectacle wear, baseline measurements of near heterophoria, accommodation response, negative and positive relative accommodations, fusional vergence, and Nonius-horopter spatial perception were taken. Measurements were repeated after a 40-minute wear, spectacles were removed, and tests were performed 20 minutes later. On a 22-participant subset, on a separate occasion, measurements of heterophoria, accommodation response, and relative accommodation were made immediately after spectacles were fitted. Most changes relative to baseline were not significant. Where effects occurred, these were nearly all associated with prism presence rather than adaptation. There were significant effects on accommodation response, but these seem to be refraction effects produced by pantoscopic tilt–induced power changes rather than perceptual effects altering accommodation. There were statistically significant effects on negative relative accommodation ( P .01), with zero prism giving more negative relative accommodation than 8 Δ base-down prisms. Tendencies were noted for prisms to move horopter limits toward the observer. Effects were small and likely not of clinical relevance. Vertically yoked prisms have minor effects on accommodation and binocular vision, at least during short-term wear in young adults with normal binocular vision.

Optical performance of progressive power lenses

Publisher: Informa UK Limited

Date: 09-1987

DOI: 10.1111/J.1444-0938.1987.TB04235.X

Equivalent power of the crystalline lens of the human eye: comparison of methods of calculation

Publisher: Optica Publishing Group

Date: 10-1997

DOI: 10.1364/JOSAA.14.002537

Abstract: We present four methods, with different levels of sophistication and precision, for calculating the refractive power of the ocular lens from its optical structure. The first method uses finite ray tracing but simulates a paraxial ray by using small ray heights. The second method involves a recursive paraxial ray-tracing procedure. The other two methods do not depend on any ray-tracing procedure but use much simpler, approximate equations. In the third method the ray height is assumed not to change within the lens, and in the fourth method the ray path is assumed to be parabolic. The fourth method, but not the third method, can separately calculate the power of the surfaces and the gradient-index lens bulk, which are then used in the three-lens equation to calculate the power of the lens as a whole.

Community Legal Centres in the Digital Era: The Use of Digital Technologies in Queensland Community Legal Centres

Publisher: Queensland University of Technology

Date: 04-11-2019

DOI: 10.5204/LTHJ.V1I0.1305

Abstract: Digital technologies are revolutionising the delivery of legal services within Australia. Challenged by innovative technologies, products and processes, the legal profession has been forced to confront their technologically disrupted future and adapt to the new technological age, as both providers and clients become progressively more reliant on increasingly sophisticated digital technology. One sector that stands to reap the benefits of digital disruption is free legal service providers, such as Community Legal Centres (CLCs), whose services benefit from the extended outreach, accessibility and efficiency that digital technologies provide. As institutions that are dedicated to ensuring that vulnerable client groups have access to justice, CLCs must be cautious not to adopt digital technologies without due thought and, consequently, potentially alienate vulnerable clients. In this new technological era, it is now more crucial than ever for CLCs to ensure that clients who may lack access to technology, are digitally illiterate, or prefer face-to-face interactions, are catered for within the CLC sector. This paper addresses the use of technology by Queensland CLCs by drawing on data collected from semi-structured, qualitative interviews with 10 employees from eight different CLCs. The article asserts that Queensland CLCs preferred to adopt digital technologies that assisted with their organisational needs over client-oriented services, attempting to strike the delicate balance between technological convenience and technological inaccessibility.

Comparison of Peripheral Refractions Determined by Different Instruments

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-2003

DOI: 10.1097/00006324-200309000-00011

Abstract: To compare peripheral refractions obtained with a Hartmann-Shack sensor instrument and two commercial autorefractors. Measurements were taken with a laboratory Hartmann-Shack instrument, the Canon Autoref R-1, and the Shin-Nippon SRW-5000 to 40 degrees in both directions along the horizontal meridian. The agreement between the Hartmann-Shack instrument and the Shin-Nippon autorefractor was good, with mean power differences varying from 0.3 D at the center of the visual field to 0.7 D at the edge of the visual field. The agreement between the Hartmann-Shack and Canon Autoref R-1 was not as good, but neither was the agreement between the Shin-Nippon and Canon instruments. The agreement between the instruments was similar to other comparisons made between different techniques. Combined with the high magnitude of peripheral refractions, this indicates that the Hartmann-Shack sensor technique can validly be extended from measuring central refractions to measuring peripheral refractions.

Does the Badal optometer stimulate accommodation accurately?

Publisher: Wiley

Date: 23-10-2016

DOI: 10.1111/OPO.12334

Abstract: To study whether the accommodation response to Badal optometer is equivalent to the response for real space targets. Accommodative responses were measured for 28 young eyes with the WAM ‐5500 autorefractometer in eight configurations for 0.17 D, 2.0 D and 5.0 D accommodation stimuli. Parameters that might contribute to differences in response were systematically isolated: stimulation method (real space vs Badal targets), field of view, instrument's cover proximity, the looming effect, and the peripheral interposition of objects in depth. Mean accommodative response differences between a natural view configuration and a configuration with a Badal Optometer were 0.50 ± 0.43 D and 0.58 ± 0.53 D for 2.0 D and 5.0 D stimulation, respectively ( p 0.001), with accommodation lags for the latter condition. Of the isolated parameters that might contribute to these differences, varying the interposition of objects in depth affected accommodation response more markedly. It is likely that Badal optometers affect accommodation through a combination of some or all of the studied parameters. We conclude that accommodation response to closed‐view Badal optometers is not equivalent to real space target response.

Effects of accommodation and simulated convergence on anterior scleral shape

Publisher: Wiley

Date: 03-06-2020

DOI: 10.1111/OPO.12697

Abstract: The sclera plays an important role in the biomechanical stability of the eye. We aimed to examine if changes in the shape of the anterior sclera occur in response to accommodation and convergence. Thirty‐six healthy young adult participants aged between 18 and 30 years including 18 myopes (–0.5 to –4.0 D) and 18 emmetropes (+0.5 to –0.25 D) were recruited. Eye surface profilometry was used to evaluate the anterior eye surface shape before and during visual tasks involving accommodation (5.0 D demand), simulated convergence (9° demand) and their combination. The changes in the sagittal height and axial radius of curvature of the nasal ( n = 25) and temporal ( n = 31) corneal periphery and anterior sclera were analysed in those participants with complete and reliable data on these sides. Significant changes were confined to the nasal anterior scleral surface. A significant forward movement of the surface accompanied accommodation (mean change: 5 ± 2 µm), convergence (19 ± 6 µm), and their combination (16 ± 6 µm). There was flattening with convergence (0.092 ± 0.044 mm) and with the combination of accommodation and convergence (0.201 ± 0.071 mm). The changes in response to accommodation and convergence increased peripherally. Changes were not significantly different between low to moderate myopes and emmetropes. Accommodation and simulated convergence affect the nasal anterior scleral shape, with the greatest changes associated with convergence and being most evident in the more peripheral nasal scleral regions.

Peripheral refraction in orthokeratology patients

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-2006

DOI: 10.1097/01.OPX.0000232840.66716.AF

Nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control contact lens

Publisher: Optica Publishing Group

Date: 12-2020

DOI: 10.1364/BOE.406101

Abstract: A combination of human subject data and optical modelling was used to investigate unexpected nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control lens. Peripheral refraction was measured with an auto-refractor and an aberrometer. Peripheral refraction with the lens was highly dependent upon instrument and method (e.g. pupil size and the number of aberration orders). A model that did not account for on-eye conformation did not mirror the clinical results, but a model assuming complete lens conformation to the anterior corneal topography accounted for the positive shift in clinically measured refraction at larger nasal field angles. The findings indicate that peripheral refraction of highly aspheric contact lenses is dependent on lens conformation and the method of measurement. These measurement methods must be reported, and care must be used in interpreting results.

Structure versus function in high myopia using optical coherence tomography and automated perimetry

Publisher: Informa UK Limited

Date: 05-2019

DOI: 10.1111/CXO.12836

Abstract: To examine the structure-function relationship between retinal thickness using spectral-domain optical coherence tomography and standard automated perimetry in high myopia. The study population comprised 58 highly myopic in iduals with no posterior abnormalities (mean spherical equivalent refraction ≤ -6.00 D and axial length ≥ 26.0 mm). All eyes underwent optical coherence tomography with the Spectralis spectral domain optical coherence tomograph and visual field evaluation with the Humphrey Field Analyzer II-i. Average macular layer thicknesses in each quadrant were calculated in a 6 × 6 mm area centred on the fovea. The visual field was assessed from 17 central locations (10°), approximately the equivalent of the area tested by optical coherence tomography in the macular scan. Linear correlations were made between different macular layer thicknesses and peripapillary retinal nerve layer thickness with their matched visual field sensitivities. Participant ages were 28.2 ± 6.4 years, mean spherical equivalent refractions were -8.20 ± 1.40 D and axial lengths were 26.7 ± 0.7 mm. There were significant positive correlations between layer thickness and corresponding visual field sensitivities as follows: ganglion cell layer in all quadrants, temporal quadrant of the nerve fibre layer with nasal quadrant of the visual field, inferior quadrant of the outer nuclear layer with superior visual field, and temporal-superior peripapillary nerve fibre layer with nasal-inferior visual field. The correlation between retinal layer thicknesses and visual field sensitivity could be explained by myopia-related losses due to lateral retinal stretching, with further research required to investigate this.

Measuring refractive index distribution in the human eye lens

Publisher: Impact Journals, LLC

Date: 13-11-2015

DOI: 10.18632/ONCOTARGET.6322

Relative peripheral defocus and myopic progression in children

Publisher: Springer Science and Business Media LLC

Date: 12-11-2014

DOI: 10.1007/S00417-013-2506-1

Noticeable, troublesome and objectionable limits of blur

Publisher: Elsevier BV

Date: 07-2005

DOI: 10.1016/J.VISRES.2005.01.022

Abstract: We investigated limits at which induced blur becomes noticeable, troublesome and objectionable. We used 15 cyclopleged subjects, a Badal optometer with lines of three high contrast letters as targets, 3-6 mm artificial pupils, and 0.0-0.7 logMAR letter sizes. For 0.0 logMAR size, mean "noticeable" blur limits were +/-0.33D, +/-0.30D and +/-0.28D at 3 mm, 4 mm and 6 mm, respectively, but increased by about 70% for 0.7 logMAR letters. All limits reduced by about 17% as pupil size increased from 3 mm to 6 mm. Letter size had a significant influence on all blur limits (1.6-2.1 times), but blur direction had no significant effect. Magnitudes of "troublesome" and 'objectionable" limits were 1.6-1.8 times and 2.1-2.5 times relative to "noticeable" limits, respectively. Our results suggest criteria for troublesome and objectionable blur are relatively unaffected by letter size.

Effect of an intervening screen on accommodation to a distant object

Publisher: Informa UK Limited

Date: 06-05-1998

DOI: 10.1111/J.1444-0938.1998.TB06730.X

Abstract: Background: An intervening screen has been suggested to induce an inward shift of accommodation when viewing a distant object. This is an ex le of the Mandelbaum effect. However, there have been no objective measures of the magnitude of this effect in this particular situation. Methods: Accommodation was recorded with an infra-red optometer, while subjects (n = 16) viewed a distant letter target with or without an intervening screen. Screens were placed near the in idual dark focus distance or at 50 cm. In a second experiment the contrast of the distant target was varied and subjects (n = 5) viewed the target directly or through a screen placed near the in idual dark focus distance. Results: In the main experiment, the Mandelbaum effect was not significantly different from zero and was less than 0.5 D in every subject. In addition, accommodation was not more variable when viewing through the screen. However, it may be that some subjects do demonstrate a Mandelbaum effect while others do not. The in idual dark focus level did not predict susceptibility to the Mandelbaum effect for a screen at the dark focus. Subjects reported their perceptions of the tasks and some noted changes in the perceived distances of objects when viewing through a screen. In the second experiment, the Mandelbaum effect (< 0.6 D) did not vary with distant target contrast. Conclusions: When viewing a distant object through a screen there is a small (< 0.6 D) or negligible inward shift of accommodation.

Two new tests assist in the diagnosis of a small calibre vein occlusion

Publisher: Informa UK Limited

Date: 03-1997

DOI: 10.1111/J.1444-0938.1997.TB04850.X

The clinical importance of spectacle lens base curves

Publisher: Informa UK Limited

Date: 1986

DOI: 10.1111/J.1444-0938.1986.TB04564.X

Standardizing sum-of-segments axial length using refractive index models

Publisher: Optica Publishing Group

Date: 25-09-2020

DOI: 10.1364/BOE.400471

Abstract: Optical biometry uses interferometry to measure the axial length (AL) of the eye. Traditionally, one-variable regression formulas have converted the optical path length measured by a biometer to a geometric AL. An alternate calculation of axial length sums the in idual segments of the eye (sum-of-segments AL). This calculation has been shown to improve predictions of some intraocular lens power formulas when used in place of traditional axial length. Sum-of-segments ALs are determined from 13 refractive index models. As measured in 1695 eyes, these yield different ocular axial lengths. A path to standardization from these models is presented.

Adaptive optics visual simulators: a review of recent optical designs and applications [Invited]

Publisher: Optica Publishing Group

Date: 17-11-2022

DOI: 10.1364/BOE.473458

Abstract: In their pioneering work demonstrating measurement and full correction of the eye’s optical aberrations, Liang, Williams and Miller, [ JOSA A 14 , 2884 ( 1997 ) 10.1364/JOSAA.14.002884 ] showed improvement in visual performance using adaptive optics (AO). Since then, AO visual simulators have been developed to explore the spatial limits to human vision and as platforms to test non-invasively optical corrections for presbyopia, myopia, or corneal irregularities. These applications have allowed new psychophysics bypassing the optics of the eye, ranging from studying the impact of the interactions of monochromatic and chromatic aberrations on vision to neural adaptation. Other applications address new paradigms of lens designs and corrections of ocular errors. The current paper describes a series of AO visual simulators developed in laboratories around the world, key applications, and current trends and challenges. As the field moves into its second quarter century, new available technologies and a solid reception by the clinical community promise a vigorous and expanding use of AO simulation in years to come.

Modeling the power of the aging human eye

Publisher: Optica Publishing Group

Date: 12-1992

DOI: 10.1364/JOSAA.9.002111

Abstract: A hypothesis is presented that may explain why the aging eye does not become myopic with age. The power of the eye lens is predicted with a modeling approach to determine how the form of the refractive-index gradient within the lens can change to maintain a constant power in spite of age-related curvature increase. Methods used include published age-dependent data on the optical parameters of the eye, a mathematical model of the lens based on elliptical isoindicial contours, and a refractive-index profile that can be expressed as a power series in the distance from the lens center. The kinds of change in profile required to prevent the eye from becoming myopic as its lens grows are shown.

Design of a focused light field fundus camera for retinal imaging

Publisher: Elsevier BV

Date: 11-2022

DOI: 10.1016/J.IMAGE.2022.116869

Technical notes on peripheral refraction, peripheral eye length and retinal shape determination

Publisher: Wiley

Date: 26-01-2023

DOI: 10.1111/OPO.13097

Abstract: To give an overview of the misconceptions and potential artefacts associated with measuring peripheral refractive error and eye length, the use of these measures to determine the retinal shape and their links to myopia development. Several issues were identified: the relationship between peripheral refractive error and myopia development, inferring the retinal shape from peripheral refraction or eye length patterns, artefacts and accuracy when measuring peripheral eye length using an optical biometer. A theory was developed to investigate the influence of artefacts in measuring peripheral eye length and on using peripheral eye length to make inferences about retinal shape. When determining peripheral axial length, disregarding the need to realign instruments with mounted targets can lead to incorrect field angles and positions of mounted targets by more than 10% for targets placed close to the eye. Peripheral eye length is not a good indicator of the effects of myopia or of treatment for myopia development because eyes of different lengths but with the same retinal shape would be interpreted as having different retinal shapes the measurement leads to overestimates of changes in retinal curvature as myopia increases. Determining peripheral eye length as a function of estimated retinal height rather than field angle will halve the magnitude of the artefact. The artefact resulting from the peripheral use of biometers with an on‐axis calibration is modest and can be ignored. There are significant issues with peripheral measurements of the refractive error and eye length that must be considered when interpreting these data for myopia research. Some of these issues can be mitigated, while others require further investigation.

Prism in pairs of progressive power lenses

Publisher: Informa UK Limited

Date: 07-1989

DOI: 10.1111/J.1444-0938.1989.TB03071.X

Effects of simulated anisometropia and aniseikonia on stereopsis

Publisher: Wiley

Date: 03-03-2020

DOI: 10.1111/OPO.12680

Abstract: Stereopsis depends on horizontally disparate retinal images but otherwise concordance between eyes. Here we investigate the effect of spherical and meridional simulated anisometropia and aniseikonia on stereopsis thresholds. The aims were to determine effects of meridian, magnitude and the relative effects of the two conditions. Ten participants with normal binocular vision viewed McGill modified random dot stereograms through synchronised shutter glasses. Stereoacuities were determined using a four‐alternative forced‐choice procedure. To induce anisometropia, trial lenses of varying power and axes were placed in front of right eyes. Seventeen combinations were used: zero (no lens) and both positive and negative, 1 and 2 D powers, at 45, 90 and 180 axes spherical lenses were also tested. To induce aniseikonia 17 magnification power and axis combinations were used. This included zero (no lens), and 3%, 6%, 9% and 12% at axes 45, 90 and 180 overall magnifications were also tested. For induced anisometropia, stereopsis loss increased as cylindrical axis rotated from 180° to 90°, at which the loss was similar to that for spherical blur. For ex le, for 2 D meridional anisometropia threshold increased from 1.53 log sec arc (i.e. 34 sec arc) for x 180 to 1.89 log sec arc (78 sec arc) for x 90. Anisometropia induced with either positive or negative lenses had similar detrimental effects on stereopsis. Unlike anisometropia, the stereopsis loss with induced meridional aniseikonia was not affected by axis and was about 64% of that for overall aniseikonia of the same amount. Approximately, each 1 D of induced anisometropia had the same effect on threshold as did each 6% of induced aniseikonia. The axes of meridional anisometropia but not aniseikonia affected stereopsis. This suggests differences in the way that monocular blur (anisometropia) and interocular shape differences (aniseikonia) are processed during the production of stereopsis.

Chromatic dispersions of the ocular media of human eyes

Publisher: Optica Publishing Group

Date: 2005

DOI: 10.1364/JOSAA.22.000029

Abstract: Of the commonly used chromatic dispersion equations, only the Sellmeier and the Cauchy equations seem to be theoretically based. Cauchy's equation is derived from the Sellmeier equation, is simpler to implement, and was found to give an excellent fit to published refractive-index data of the human eye. We used Cauchy's equation to model the chromatic difference in refraction of the Gullstrand number 1 schematic eye with a gradient-index lens. To estimate the dispersion at different refractive-index levels within the lens, a single dispersion equation at one nominal refractive index was linearly scaled. This scaling was justified after exploring the effect of mean refractive index on dispersion by using Sellmeier's equation and finding that a dispersion equation for one wavelength is just a linearly scaled version of the dispersion equation at any other wavlength. Because Cauchy's equation is theoretically based and gives excellent fit to data in the visible spectrum, it can be used to extrapolate results into the near infrared with confidence.

Improvements to Phakometry Using Bessel Beams

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-2017

DOI: 10.1097/OPX.0000000000001130

Abstract: The main problem with phakometry is the low visibility of the third Purkinje image. We built a phakometer using Bessel beams, which have properties of being resistant to diffraction and the potential for self-reconstruction. This instrument had lenticular images three times brighter than those of a conventional phakometer. To investigate Purkinje image brightness, accuracy, and repeatability of a “Bessel” phakometer compared with those of a conventional phakometer. Phakometers were developed with a telecentric imaging system focused at the pupil plane of the eye to capture anterior cornea, anterior lens (PIII), and posterior lens (PIV) Purkinje images. A Bessel beam was generated by a diode laser beam passing through a high-powered doublet with a central obstruction. Software was used to determine image sizes and estimate lens anterior and posterior surface radii of curvature ( R a , R p ), equivalent refractive index (RI), and equivalent power ( F ). The Bessel phakometer's accuracy was assessed using a model eye. Repeatability (interobserver and intraobserver) and Purkinje images brightnesses of Bessel and conventional phakometers were assessed with six participants. The lens parameters of the model eye determined by the Bessel phakometer were similar to those provided by the model eye's manufacturer with differences (manufacturer − Bessel) in R a and R p , RI, and F of +1.18 mm, 0.18 mm, +0.0053, and −0.55 D, respectively. The intraobserver repeatabilities for the Bessel and conventional phakometers were similar. The interobserver repeatabilities of R a , R p , and RI for the Bessel phakometer were almost half those (i.e., two times better) for the conventional phakometer. Brightnesses of PIII and PIV were approximately three times higher with the Bessel phakometer than with the conventional phakometer. The Bessel beam phakometer provided accurate estimates of lens parameters of a model eye and produced brighter Purkinje images and better interobserver repeatability than that of a conventional phakometer.

Aspheric Surfaces and Lenses in Ophthalmic Optics

Publisher: Informa UK Limited

Date: 07-1985

DOI: 10.1111/J.1444-0938.1985.TB01074.X

Effect of Age on Components of Peripheral Ocular Aberrations

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-2012

DOI: 10.1097/OPX.0B013E31825DA172

Blur limits for defocus, astigmatism and trefoil

Publisher: Elsevier BV

Date: 09-2009

DOI: 10.1016/J.VISRES.2009.07.009

Abstract: We investigated the limits at which blur due to defocus, crossed-cylinder astigmatism, and trefoil became noticeable, troublesome or objectionable. Black letter targets (0.1, 0.35 and 0.6 logMAR) were presented on white backgrounds. Subjects were cyclopleged and had effectively 5mm pupils. Blur was induced with a deformable, adaptive-optics mirror operating under open-loop conditions. Mean defocus blur limits of six subjects with uncorrected intrinsic higher-order ocular aberrations ranged from 0.18+/-0.08 D (noticeable blur criterion, 0.1 logMAR) to 1.01+/-0.27 D (objectionable blur criterion, 0.6 logMAR). Crossed-cylinder astigmatic blur limits were approximately 90% of those for defocus, but with considerable meridional influences. In two of the subjects, the intrinsic aberrations of the eye were subsequently corrected before the defocus and astigmatic blur were added. This resulted in only minor reductions in their blur limits. When assessed with trefoil blur and corrected intrinsic ocular aberrations, the ratio of objectionable to noticeable blur limits in these two subjects was much higher for trefoil (3.5) than for defocus (2.5) and astigmatism (2.2).

Laboratory evaluation of blended lenticular aphakic lenses

Publisher: Wiley

Date: 07-1988

DOI: 10.1111/J.1475-1313.1988.TB01057.X

Neogene cratonic erosion fluxes and landform evolution processes from regional regolith mapping (Burkina Faso, West Africa)

Publisher: Elsevier BV

Date: 07-2015

DOI: 10.1016/J.GEOMORPH.2015.04.006

Peripheral Refraction Validity of the Shin-Nippon SRW5000 Autorefractor

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 10-2016

DOI: 10.1097/OPX.0000000000000954

Abstract: To investigate the operation of the Shin-Nippon/Grand Seiko autorefractor and whether higher-order aberrations affect its peripheral refraction measurements. Information on instrument design, together with parameters and equations used to obtain refraction, was obtained from a patent. A model eye simulating the operating principles was tested with an optical design program. Effects of induced defocus and astigmatism on the retinal image were used to calibrate the model eye to match the patent equations. Coma and trefoil were added to assess their effects on the image. Peripheral refraction of a physical model eye was measured along four visual field meridians with the Shin-Nippon/Grand Seiko autorefractor SRW-5000 and a Hartmann-Shack aberrometer, and simulated autorefractor peripheral refraction was derived using the Zernike coefficients from the aberrometer. In simulation, the autorefractor’s square image was changed in size by defocus, into rectangles or parallelograms by astigmatism, and into irregular shapes by coma and trefoil. In the presence of 1.0 D oblique astigmatism, errors in refraction were proportional to the higher-order aberrations, with up to 0.8 D sphere and 1.5 D cylinder for ±0.6 μm of coma or trefoil coefficients with a 5-mm-diameter pupil. For the physical model eye, refraction with the aberrometer was similar in all visual field meridians, but refraction with the autorefractor changed more quickly along one oblique meridian and less quickly along the other oblique meridian than along the horizontal and vertical meridians. Simulations predicted that higher-order aberrations would affect refraction in oblique meridians, and this was supported by the experimental measurements with the physical model eye. The autorefractor’s peripheral refraction measurements are valid for horizontal and vertical field meridians, but not for oblique field meridians. Similar instruments must be validated before being adopted outside their design scope.

Colour vision in a family with Sorsby's dystrophy

Publisher: Wiley

Date: 12-1989

DOI: 10.1111/J.1755-3768.1989.TB04393.X

Abstract: Fraser & Wallace (1971) investigated a family with Sorsby's dystrophy, and found a high prevalence of a mild red-green colour deficiency. Using a battery of tests, I re-examined the colour vision of members of the family at risk of developing the disease. I conclude that the mild colour vision defect is classical sex linked recessive deuteranomaly occurring adventiously in the family its high prevalence is due to its being introduced by at least 3 persons marrying into the family. Two alternative hypotheses of the colour vision deficiency are that it is an acquired disorder which is a prodromal sign of the dystrophy or that it is inherited in an autosomal dominant manner. However, these hypotheses were rejected because the colour vision deficiency had the characteristics of a typical sex linked disorder. These findings emphasize that it is important to exclude any co-existing inherited colour vision defect when defining the clinical features of any retinal dystrophy by careful evaluation of unaffected family members.

Influences of luminance and accommodation stimuli on pupil size and pupil center location

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 07-04-2014

DOI: 10.1167/IOVS.13-13492

Abstract: We investigated effects of luminance and accommodation stimuli on pupil size and pupil center location, and their implications for progressive addition lens wear. Participants were young and older adult groups (n = 20 22 ± 2 years age range, 18-25 years and n = 19 49 ± 4 years age range, 45-58 years). A wave aberrometer included a relay system to allow a 12.5° × 11° background for the internal fixation target. Participants viewed the target under a matrix of conditions with luminance levels 0.01, 3.7, 120, and 6100 cd/m(2), and with accommodation stimuli up to 6 diopters (D) in 2 D steps. Pupil sizes and their centers, relative to limbus centers, were determined from anterior eye images. With luminance increase, reduction in pupil size was accentuated by increase in accommodation stimulus in the young, but not in the older, group. As luminance increased, pupil center location altered. This was nasally in both groups with an average shift of approximately 0.12 mm. Relative to the lowest stimulus condition, the mean of the maximum absolute pupil center shifts was 0.26 ± 0.08 mm for both groups with in idual shifts up to 0.5 mm, findings consistent with previous studies. There was no significant effect of accommodation on pupil center locations for either age group, or evidence that location was influenced by the combination of luminance and accommodation stimulus that resulted in any particular pupil size. Variations in luminance and accommodation influence pupil size, but only the former affects pupil center location significantly. Pupil center shifts are too small to be of concern in fitting progressive addition lenses.

Time Course of Pupil Center Location after Ocular Drug Application

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 06-2016

DOI: 10.1097/OPX.0000000000000837

Myopia: Why Study the Mechanisms of Myopia? Novel Approaches to Risk Factors Signaling Eye Growth- How Could Basic Biology Be Translated into Clinical Insights? Where Are Genetic and Proteomic Approac

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2011

DOI: 10.1097/OPX.0B013E31820E6A6A

Visual performance with lenses correcting peripheral refractive errors

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-2013

DOI: 10.1097/OPX.0000000000000033

Pseudoaccommodation with forward movement of IOLs

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 2005

DOI: 10.1016/J.JCRS.2004.11.022

Binocular Summation Improves Performance to Defocus-Induced Blur

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 25-04-2011

DOI: 10.1167/IOVS.10-6545

Abstract: To assess whether there are any advantages of binocular over monocular vision under blur conditions. The effect of defocus, induced by positive lenses, was measured on the pattern reversal visual evoked potential (VEP) and on visual acuity (VA). Monocular (dominant eye) and binocular VEPs were recorded from 13 volunteers (average age, 28 ± 5 years average spherical equivalent, -0.25 ± 0.73 D) for defocus up to 2.00 D using positive powered lenses. VEPs were elicited using reversing 10 arcmin checks (4 reversals/s). The stimulus subtended a circular field of 7° with 100% contrast and mean luminance 30 cd/m(2). VA was measured under the same conditions using ETDRS charts. All measurements were performed at 1 m viewing distance with best spectacle sphero-cylindrical correction and natural pupils. With binocular stimulation, litudes and implicit times of the P100 component of the VEPs were greater and shorter, respectively, in all cases than for monocular stimulation. Mean binocular enhancement ratio in the P100 litude was 2.1 in focus, increasing linearly with defocus to be 3.1 at +2.00 D defocus. Mean peak latency was 2.9 ms shorter in focus with binocular than for monocular stimulation, with the difference increasing with defocus to 8.8 ms at +2.00 D. As for the VEP litude, VA was always better with binocular than with monocular vision, with the difference being greater for higher retinal blur. Both subjective and electrophysiological results show that binocular vision ameliorates the effect of defocus. The increased binocular facilitation observed with retinal blur may be due to the activation of a larger population of neurons at close-to-threshold detection under binocular stimulation.

Errata: Higher order aberrations across the horizontal visual field

Publisher: SPIE-Intl Soc Optical Eng

Date: 2006

DOI: 10.1117/1.2348896

Central and peripheral choroidal thickness and eye length changes during accommodation

Publisher: Wiley

Date: 04-01-2023

DOI: 10.1111/OPO.13084

Abstract: Eye length increases during accommodation, both on‐axis and in the periphery. The aim of this study was to determine whether the peripheral choroid thins with accommodation and to determine the relationship with eye length changes measured at the same location. Subjects included 53 young adults in good ocular and general health, with 19 emmetropes and 34 myopes. Measurements from the right eye were made for 0 D and 6 D accommodation stimuli for ±30° horizontal visual field/retinal locations in 10° steps. Valid eye length and choroidal thickness measurements were obtained for 37 and 47 participants, respectively, and both measures were taken for 31 participants. 2.5% phenylephrine was instilled to dilate the pupils. Participants turned their eyes, without head movement, to fixate targets and to make the target ‘as clear as possible’ during measurements. Correction was made for the influence of lens thickness changing at different peripheral angles. Choroidal thickness was measured with a spectral‐domain‐Optical Coherence Tomographer. For peripheral images, the internal cross target on the capture screen was moved from the centre to 17.25° nasal/temporal positions. In accordance with previous literature, eye length increased with accommodation. The greatest change (mean ± SD) of 41 ± 17 μm occurred at the centre, with a mean change across the locations of 33 μm. There were no significant differences between emmetropes and myopes. Choroidal thickness decreased with accommodation, with changes being about two‐thirds of those occurring for eye length. The greatest change of −30 ± 1 μm occurred at the centre, with a mean change of −21 μm. Greater choroidal thinning occurred for myopes than for emmetropes (23 ± 11 vs. 17 ± 8 μm, p = 0.02). With accommodation, eye length increased and the choroid thinned, at both central and peripheral positions. Choroidal thinning accounted for approximately 60% of the eye length increase across the horizontal ±30°.

Power profiles of multifocal contact lenses and their interpretation

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 10-2013

DOI: 10.1097/OPX.0000000000000030

Higher-order aberrations and anisometropia

Publisher: Informa UK Limited

Date: 15-11-2013

DOI: 10.3109/02713683.2012.738462

Abstract: Myopia incidence is increasing around the world. Myopization is considered to be caused by a variety of factors. One consideration is whether higher-order aberrations (HOA) influence myopization. More knowledge of optics in anisometropic eyes might give further insight into the development of refractive error. To analyze the possible influence of HOA on refractive error development, we compared HOA between anisometropes and isometropes. We analyzed HOA up to the 4th order for both eyes of 20 anisometropes (mean age: 43 ± 17 years) and 20 isometropes (mean age: 33 ± 17 years). HOA were measured with the Shack-Hartman i.Profiler (Carl Zeiss, Germany) and were recalculated for a 4 mm pupil. Mean spherical equivalent (MSE) was based on the subjective refraction. Anisometropia was defined as ≥1 D interocular difference in MSE. The mean absolute differences between right and left eyes in spherical equivalent were 0.28 ± 0.21 D in the isometropic group and 2.81 ± 2.04 D in the anisometropic group. Interocular differences in HOA were compared with the interocular difference in MSE using correlations. For isometropes oblique trefoil, vertical coma, horizontal coma and spherical aberration showed significant correlations between the two eyes. In anisometropes, all analyzed higher-order aberrations correlated significantly between the two eyes except oblique secondary astigmatism and secondary astigmatism. When analyzing anisometropes and isometropes separately, no significant correlations were found between interocular differences of higher-order aberrations and MSE. For isometropes and anisometropes combined, tetrafoil correlated significantly with MSE in left eyes. The present study could not show that interocular differences of higher-order aberrations increase with increasing interocular difference in MSE.

Optical Design of Intraocular Lenses. II. Off-Axis Performance

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-1989

DOI: 10.1097/00006324-198909000-00003

Abstract: The effect of intraocular lens shape on off-axis performance of model pseudophakic eyes was investigated. Image quality criteria included an optimization procedure, spot diagrams, and the modulation transfer function (MTF). The optimum lens shape varies with lens fitting position, corneal asphericity, and pupil size. An earlier investigation showed that the optimum lens shape for on-axis imagery is approximately plano-convex, with the more curved surface facing the cornea. In this investigation, optimum lens shapes for a 10 degrees off-axis position ranged from near this shape to near the reversed shape, i.e., the more curved surface facing the retina. Because the on-axis case should carry more weight and because conditions favoring the reverse form include small pupils for which image quality is fairly insensitive to variations in lens shape, it is suggested that good forms for intraocular lenses range from plano-convex (curved surface facing cornea) to equi-convex.

Effects of induced aniseikonia on binocular visual acuity

Publisher: Informa UK Limited

Date: 17-05-2023

DOI: 10.1080/08164622.2023.2203315

Law, Video Games, Virtual Realities

Publisher: Routledge

Date: 29-08-2023

DOI: 10.4324/9781003197805

Performance of aspheric spectacle lenses

Publisher: Informa UK Limited

Date: 11-1992

DOI: 10.1111/J.1444-0938.1992.TB00767.X

Influences of reference plane and direction of measurement on eye aberration measurement

Publisher: Optica Publishing Group

Date: 12-2005

DOI: 10.1364/JOSAA.22.002589

Abstract: We explored effects of measurement conditions on wave aberration estimates for uncorrected, axially myopic model eyes. Wave aberrations were initially referenced to either the anterior corneal pole or the natural entrance pupil of symmetrical eye models, with rays traced into the eye from infinity (into the eye) to simulate normal vision, into the eye from infinity and then back out of the eye from the retinal intercepts (into/out of the eye), or out of the eye from the retinal fovea (out of the eye). The into-the-eye and out-of-the-eye ray traces gave increases in spherical aberration as myopia increased, but the into/out-of-the-eye ray trace showed little variation in spherical aberration. Reference plane choice also affected spherical aberration. Corresponding residual aberrations were calculated after the models had been optically corrected, either by placing the object or image plane at the paraxial far point or by modifying corneas to simulate laser ablation corrections. Correcting aberrations by ablation was more complete if the original aberrations were referenced to the cornea rather than to the entrance pupil. For eyes corrected by spectacle lenses, failure to allow for effects of pupil magnification on apparent entrance pupil diameter produced larger changes in measured aberrations. The general findings regarding choice of reference plane and direction of measurement were found to be equally applicable to eyes that lacked rotational symmetry.

Aberrations of emmetropic subjects at different ages

Publisher: Elsevier BV

Date: 09-2008

DOI: 10.1016/J.VISRES.2008.06.023

Abstract: We made on-axis aberrations and horizontal peripheral refraction measurements of emmetropic subjects (spherical equivalent -0.88D to +0.75D) aged between 19 and 70 years. We found smaller changes in on-axis aberrations with age than has previously been reported, possibly because of the small refractive error range of our subject group. Higher order root-mean-squared aberrations increased by 26% across the age range (5 mm pupils), with significant age related changes in 4th- and 6th-order aberrations. The only aberration co-efficient to change significantly was horizontal coma co-efficient C(3, 1). Several aberration co-efficients were significantly different from zero across the group of subjects. The only changes in peripheral refraction with increase in age were shifts in the turning points of the spherical equivalent and horizontal/vertical astigmatism towards less temporal visual field angles.

On the Description of Zonal Aspheric Surfaces

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 02-1986

DOI: 10.1097/00006324-198602000-00012

Abstract: It is shown that, in general for a rotationally symmetric surface, the sagittal curvature is a function of the first derivative and tangential curvature is a function of the first and second derivatives of the surface equation. Smith and Atchison developed an "off-set" model for zonal aspheric surfaces with continuous gradients (or first derivatives) at the boundaries between zones of the surface, and discontinuous second derivatives at the boundaries. This model predicts continuous sagittal power errors but discontinuities in tangential power errors. However, measurements on commercially available zonal lenses by Atchison and Smith showed that both sagittal and tangential power errors were continuous across zone boundaries. Thus it is likely that the off-set model is incorrect. Zonal aspheric surfaces are more likely to be made according to a "co-axial" model which is described.

Dynamic accommodation response in the presence of astigmatism

Publisher: Optica Publishing Group

Date: 12-2003

DOI: 10.1364/JOSAA.20.002228

Abstract: It has been suggested that in the presence of astigmatism some in iduals make cyclic changes in focus over the astigmatic interval to obtain better visual performance. The aim in the present study was to identify such cyclic accommodative behavior and to characterize the variability of the response in the presence of astigmatism. The dynamic accommodation response in the presence of induced astigmatism was recorded objectively with an infrared optometer in seven young adults. Astigmatism led directly to increased accommodative variability in certain in iduals. In two of seven participants there was evidence for aperiodic cyclic accommodative responses between different portions of the astigmatic interval. However, the litude of these tracking responses was much smaller than the astigmatic interval.

The influence of the Stiles–Crawford peak location on visual performance

Publisher: Elsevier BV

Date: 03-2003

DOI: 10.1016/S0042-6989(02)00681-8

Abstract: We investigated the influence of the Stiles-Crawford peak location on visual acuity, contrast sensitivity and phase transfer with 6 mm diameter pupils in two subjects. Apodising filters were used to move the peak. One subject (SM) had her natural peak 0.9 mm below pupil centre, and visual performance was measured for both this peak position and when the peak was moved to the same distance above pupil centre. The other subject (DAA) had a more centred peak and visual performance was measured for this peak position and when the peak was moved both 2.3 mm temporally and 2.6 mm nasally. Measurements of contrast sensitivity and phase transfer were compared with predictions based on aberration measurements. The peak position had definite influence on performance, but this was mainly noticeable when subjects were defocused e.g. SM's visual acuity was reduced by 0.13 log units under the peak-shifted condition at -2D (hypermetropic) defocus.

Measurement of Monochromatic Ocular Aberrations of Human Eyes as a Function of Accommodation by the Howland Aberroscope Technique

Publisher: Elsevier BV

Date: 02-1995

DOI: 10.1016/0042-6989(94)00139-D

Abstract: Further development of the objective version of the Howland and Howland [(1976) Science, 193, 580-582 (1977) Journal of the Optical Society of America, 67, 1508-1518] aberroscope technique for measuring ocular aberrations is described. Compensation for refractive corrections and calibration is discussed. The technique was used to investigate the effect of accommodation upon the monochromatic aberrations of the right eyes of 15 subjects. Coma and coma-like aberrations were the dominant aberrations for most people at different accommodation levels, thus confirming previous findings. Variations in aberrations were considerable between subjects. About half the subjects showed the classical trend towards negative spherical aberration with accommodation. Changes in spherical aberration with accommodation in this study were less than found in previous studies where all monochromatic aberration was considered to be spherical aberration.

Hartmann–Shack technique and refraction across the horizontal visual field

Publisher: Optica Publishing Group

Date: 06-2003

DOI: 10.1364/JOSAA.20.000965

Abstract: We compared refractions across the horizontal visual field, based on different analyses of wave aberration obtained with a Hartmann-Shack instrument. The wave aberrations had been determined for 6-mm-diameter pupils up to at least the sixth Zernike order in five normal subjects [J. Opt. Soc. Am. A 19, 2180 (2002)]. The polynomials were converted into refractions based on 6-mm pupils and second-order Zernike aberrations (6 mm/2nd order), 3-mm pupils and second-order aberrations (3 mm/2nd order), 1-mm pupils and second-order aberrations (1 mm/2nd order), and 6-mm pupils with both second- and fourth-order aberrations (6 mm/4th order). The 3-mm/2nd-order and 6-mm/2nd-order refractions differed by as much as 0.9 D in mean sphere on axis, but the differences reduced markedly toward the edges of the visual field. The cylindrical differences between these two analyses were small at the center of the visual field (<0.3 D) but increased into the periphery to be greater than 1.0 D for some subjects. Much smaller differences in mean sphere and cylinder were found when 3-mm/2nd-order refractions and either the 1-mm/2nd-order refractions or the 6-mm/4th-order refractions were compared. The results suggest that, for determining refractions based on wave aberration data with large pupils, similar results occur by either restricting the analysis to second-order Zernike aberrations with a smaller pupil such as 3 mm or using both second- and fourth-order Zernike aberrations. Since subjective refraction is largely independent of the pupil size under photopic conditions, objective refractions based on either of these analyses may be the most useful.

Off-axis refraction and aberrations following conventional laser in situ keratomileusis

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2005

DOI: 10.1016/J.JCRS.2004.05.059

Abstract: To investigate off-axis refraction and aberrations following conventional laser in situ keratomileusis (LASIK) for myopia and hypermetropia. School of Optometry, Queensland University of Technology, Australia. Using an autorefractor, off-axis refractions were analyzed along the horizontal visual field between 35 degrees nasally and 35 degrees temporally in 1 eye each of 15 emmetropic subjects (-0.50 to +0.50 diopters [D]), 6 myopic subjects (-2.25 to -6.50 D), 6 hyperopic subjects (+1.50 to +3.00 D), 6 myopic LASIK patients (presurgical refraction -2.75 to -9.00 D), and 6 hyperopic LASIK patients (presurgical refraction +0.75 to +2.00 D). Wavefront sensing measured off-axis higher-order aberrations in 2 myopic LASIK patients. In myopic LASIK, the mean spherical components of refraction M became highly myopic away from the center of the visual field in emmetropic and untreated myopic eyes, there were relatively small myopic shifts and hyperopic shifts, respectively. Off-axis 90-degree to 180-degree astigmatisms J180 in myopic LASIK subjects were greater than in untreated subjects. In hyperopic LASIK, there were mainly hyperopic shifts in M, opposite the direction in emmetropic and untreated hyperopic subjects. Off-axis J180 was less than in emmetropic and untreated hyperopic subjects. Some hyperopic LASIK patients had greater off-axis 45-degree to 135-degree astigmatisms J45 than patients in the other groups. In 2 myopic LASIK patients, Zernike root-mean-square 4th-order aberrations were higher than in the near-emmetropia group because of higher levels of positive spherical aberration. Off-axis aberrations can be dramatically affected by conventional myopic and hyperopic LASIK. In myopic LASIK, the increased off-axis refractive errors may have adverse effects on peripheral visual tasks that are dependent on off-axis refractive errors. The relatively low off-axis refractive errors in hyperopic LASIK patients may improve peripheral visual tasks.

Who needs optics?

Publisher: Informa UK Limited

Date: 2003

DOI: 10.1111/J.1444-0938.2003.TB03052.X

Calibration of the Canon Autoref R-1 for continuous measurement of accommodation

Publisher: Wiley

Date: 04-1993

DOI: 10.1111/J.1475-1313.1993.TB00453.X

Abstract: The Canon Autoref R-1 is an infrared optometer which allows free-space viewing. Pugh and Winn described hardware modifications necessary to convert the Autoref R-1 from an instrument capable of taking single static measurements of the eye's accommodative (refractive) status to an instrument capable of continuous measurement of the accommodative status of the eye. We describe two methods of calibrating the Autoref R-1 for continuous measurement of accommodation for any in idual eye. The assumptions and sources of error underlying these calibration techniques are discussed. We also describe further hardware modifications to simplify signal acquisition from the Autoref R-1.

Wavefront refraction and correction

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 10-2014

DOI: 10.1097/OPX.0000000000000373

Handbook of Visual Optics, Volume One

Publisher: CRC Press

Date: 17-02-2017

DOI: 10.1201/9781315373034

Dot Motion Perception in Young Adult Emmetropes and Myopes

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 06-2018

DOI: 10.1097/OPX.0000000000001223

Abstract: Central motion perception, as assessed by minimum displacement detection, was reduced in highly myopic eyes. Peripheral motion detection may be influenced by myopia, particularly in the inferior-nasal retina. Motion discrimination is a complex visual task processed mainly via the magnocellular pathway. We investigated whether it is affected in myopia. Ninety young adults aged 18 to 28 years participated: 30 emmetropes (spherical equivalent refractions +1.00 to −0.50 diopters [D]), 30 low myopes −1.00 to −4.75 D) and 30 higher myopes ( −5 D). Random dot patterns were used to measure motion perception thresholds for minimum displacement ( D min ), maximum displacement ( D max ), and motion coherence tasks. Each task was performed centrally and at four oblique peripheral visual field locations (at 3.65 and 12 degrees for D min and D max tasks, respectively). Macular retinal thickness was measured with optical coherence tomography. The central D min task was correlated significantly with refraction ( r = −0.303, P = .004) and axial length ( r = +0.224, P = .04), and the superior-temporal field D min task was correlated significantly with axial length ( r = 0.230, P = .04). Higher myopes had poorer performance than emmetropes by 25% (higher values). For the D min peripheral task and for D max and coherence tasks at both central and peripheral locations, there were no significant correlations with refraction or axial length. At three of four positions, the peripheral D min task was correlated significantly with thickness in the corresponding retinal region: superior-temporal D min (Pearson r = −0.357, P .001), inferior-nasal D min ( r = −0.237, P = .03) and inferior-temporal D min ( r = −0.233, P = .03). Central motion perception, as assessed by minimum displacement detection, was reduced by 25% in highly myopic eyes. Peripheral motion detection may be influenced by myopia, particularly in the inferior-nasal retina. Retinal stretching due to axial elongation may be linked to reduced performance in higher myopes.

Monocular Accommodation Response for Totally Occluded Objects

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 10-2002

DOI: 10.1097/00006324-200210000-00012

Abstract: To investigate the accuracy and stability of the monocular accommodation response when attention is directed toward a totally occluded distant object. A static infrared optometer was used to measure the monocular accommodative response in 16 participants while they viewed a distant letter target in the presence or absence of an intervening object that totally occluded the distant target from view. Participants were instructed to attend to and focus for the distant target. Participants differed widely in their accommodative responses for a totally occluded distant object, focusing close to the distant object, close to the intervening object, in between the two objects, and beyond the distant object. Some of this variability could be attributed to in idual differences in the dark focus. Accommodation was more variable when the distant target was totally occluded by an obstruction at an intermediate distance (50 cm). Many in iduals focus poorly in the presence of a visual obstruction that totally occludes the object of regard.

New thinking about presbyopia: Guest editorial

Publisher: Informa UK Limited

Date: 05-2008

DOI: 10.1111/J.1444-0938.2008.00264.X

Subjective depth-of-focus of the eye

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-1997

DOI: 10.1097/00006324-199707000-00019

Abstract: An experiment is described in which the subjective depth-of-focus (DOF) of the eye, defined as the range of focusing errors for which the image of the target appears to have the same clarity, contrast, and form as the optimal in-focus image, was measured as a function of the size of high contrast (99%) Snellen Es for 5 trained subjects under cycloplegia. Mean DOF increased by approximately 60% as the size of the letter detail increased from -0.2 to 0.87 log min arc (Snellen equivalent: 6/3.8 to 6/45), although there were considerable intersubject variations. DOF declined with increasing pupil diameter, the mean total DOFs being 0.86, 0.59, and 0.55 D for 2-, 4-, and 6-mm pupils, respectively. In a second experiment, use of low (21%) contrast letters with a 4-mm pupil and 4 subjects marginally increased the DOF (by 0.08 +/- 0.05 D) refraction also shifted in a myopic direction by a mean of 0.15 +/- 0.06 D compared with the high contrast letters. A third experiment with four less-experienced subjects demonstrated the importance of instruction and training in any measurement involving judgment of just-perceptible defocus blur. The clinical implications of the results for measurements of refraction and litude of accommodation are discussed.

Consequences of monocular diplopia for the contrast sensitivity function

Publisher: Elsevier BV

Date: 11-1996

DOI: 10.1016/0042-6989(96)00091-0

Abstract: Though the human eye generally creates a single image on the retina, the literature contains many ex les showing perceptual monocular diplopia. Previously, monocular diplopia resulting from astigmatic defocus has been demonstrated to cause a notch (local minimum) in the contrast sensitivity function (CSF). We examine Verhoeff's (1900) model which explains how monocular diplopia can occur through an interaction between defocus and common ocular aberrations. From the measured ocular transverse aberration function and from the measured monocular diplopia of three cyclopleged subjects we predicted multiple notches in the CSF with hyperopic spherical defocus. Monochromatic and polychromatic CSF were measured for vertical gratings with best refraction and with simulated myopia and hyperopia. Multiple notches in CSF were observed experimentally. Notches in the polychromatic CSF were smaller and broader than those found in the monochromatic CSF. Our aberration model was successful in predicting notches in the CSF with hyperopic spherical defocus. The implications for clinical measurement of CSF are discussed.

Influence of eye rotation on peripheral eye length measurement obtained with a partial coherence interferometry instrument

Publisher: Wiley

Date: 11-12-2013

DOI: 10.1111/OPO.12095

Abstract: The eye rotation approach for measuring peripheral eye length leads to concern about whether the rotation influences results, such as through pressure exerted by eyelids or extra-ocular muscles. This study investigated whether this approach is valid. Peripheral eye lengths were measured with a Lenstar LS 900 biometer for eye rotation and no-eye rotation conditions (head rotation for horizontal meridian and instrument rotation for vertical meridian). Measurements were made for 23 healthy young adults along the horizontal visual field (± 30°) and, for a subset of eight participants along the vertical visual field (± 25°). To investigate the influence of the duration of eye rotation, for six participants measurements were made at 0, 60, 120, 180 and 210 s after eye rotation to ± 30° along horizontal and vertical visual fields. Peripheral eye lengths were not significantly different for the conditions along the vertical meridian (F1,7 = 0.16, p = 0.71). The peripheral eye lengths for the conditions were significantly different along the horizontal meridian (F1,22 = 4.85, p = 0.04), although not at in idual positions (p ≥ 0.10) and were not important. There were no apparent differences between the emmetropic and myopic groups. There was no significant change in eye length at any position after maintaining position for 210 s. Eye rotation and no-eye rotation conditions were similar for measuring peripheral eye lengths along horizontal and vertical visual field meridians at ± 30° and ± 25°, respectively. Either condition can be used to estimate retinal shape from peripheral eye lengths.

Decentred optical axes and aberrations along principal visual field meridians

Publisher: Elsevier BV

Date: 07-2009

DOI: 10.1016/J.VISRES.2009.04.024

Abstract: Suggestions that peripheral imagery may affect the development of refractive error have led to interest in the variation in refraction and aberration across the visual field. It is shown that, if the optical system of the eye is rotationally symmetric about an optical axis which does not coincide with the visual axis, measurements of refraction and aberration made along the horizontal and vertical meridians of the visual field will show asymmetry about the visual axis. The departures from symmetry are modelled for second-order aberrations, refractive components and third-order coma. These theoretical results are compared with practical measurements from the literature. The experimental data support the concept that departures from symmetry about the visual axis in the measurements of crossed-cylinder astigmatism J(45) and J(180) are largely explicable in terms of a decentred optical axis. Measurements of the mean sphere M suggest, however, that the retinal curvature must differ in the horizontal and vertical meridians.

Useful Variations of the Badal Optometer

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-1995

DOI: 10.1097/00006324-199504000-00010

Abstract: The simple Badal Optometer consists of a movable target and a fixed positive power lens placed at its focal distance away from the eye. The perceived angular size of the target is independent of target position and the power scale is linear. Limitations of the simple Badal Optometer include restriction of negative (myopic) ocular vergence range, the need for targets to be small, and the problem of "proximal" accommodation. We describe two modifications to the Badal system in which these limitations may be overcome by the use of a movable auxiliary optical system. In one modification, the movable auxiliary system consists of a target and positive lens which together may provide a virtual "target" for the Badal lens and thus increase the negative range. In the second modification, the Badal lens is positioned as it would normally be, but the target is an image of a distant stimulus created by the auxiliary lens. The target position (and hence the ocular vergence) is changed by moving the auxiliary lens. The distant target eliminates the proximal accommodative stimulus and allows spatial detail near the resolution limit to be displayed.

Design of aspheric intraocular lenses

Publisher: Wiley

Date: 04-1991

DOI: 10.1111/J.1475-1313.1991.TB00213.X

Abstract: The value of aspherizing intraocular lens surfaces for the purpose of improving retinal image quality of pseudophakic eyes was investigated. Surfaces were made as conicoids. Changes in primary wave aberrations and refractive errors were found to be proportional to changes in surface asphericity. The optimum asphericity depends markedly on ocular parameters, lens fitting position and how well lenses are centred within the eye. If lenses are not well centred, the asphericity that eliminates spherical aberration may result in poorer performance than that occurring with spherical surfaces. It is suggested that there is no general benefit in aspherizing surfaces of intraocular lenses.

Effects of a semi-scleral contact lens on refraction and higher order aberrations

Publisher: Elsevier BV

Date: 12-2019

DOI: 10.1016/J.CLAE.2019.06.002

Abstract: To investigate effects of Rose K2 XL semi-scleral contact lenses (Menicon Co.) on visual acuity and higher-order aberrations in eyes with irregular corneas. One hundred and twelve eyes of 84 patients fitted with Rose K2 XL lenses were analysed. Participants were in 4 clinical groups: keratoconus, intra-corneal ring segments, radial keratotomy, and penetrating keratoplasty. Corrected distance visual acuity and ocular aberrations were determined before lens wear and 60 min into lens wear. The i-Trace aberrometer was used to determine aberrations at 4.5 mm pupil size. There were 55, 22, 19 and 16 eyes in keratoconus, intra-corneal ring segments, radial keratotomy and penetrating keratoplasty groups, respectively. Before lens wear, eyes had poor corrected distance vision acuity (mean and standard deviation +0.55 ± 0.33 logMAR), high negative spherical equivalent refraction (-6.4 ± 3.7 D), high cylindrical errors (4.5 ± 2.2 D), large higher-order root-mean-squared (HO-RMS) aberration (1.5 ± 1.3 μm) and large higher-order aberration components. Cylinder was particular high for the penetrating keratoplasty group (mean 5.9 ± 2.5 D), root-mean-squared third-order coma was lowest for the radial keratotomy group (0.7 ± 1.0 μm), and fourth-order spherical aberration was highly negative for the intra-corneal ring segment group (co-efficient -0.4 ± 0.7 μm). With lens wear, the values changed considerably. Corrected distance visual acuity improved by 0.51 ± 0.31 logMAR, cylinder decreased by 3.6 ± 2.1 D, HO-RMS aberration reduced by 1.1 ± 1.2 μm, and higher-order aberration components decreased considerably. Magnitudes of group changes reflected the magnitudes before lens wear. Rose K2 XL semi-scleral contact lenses were effective in improving vision and reducing ocular aberrations for eyes with irregular corneas.

Guest Editorial: Wavefront aberrations and their clinical application

Publisher: Informa UK Limited

Date: 05-2009

DOI: 10.1111/J.1444-0938.2009.00380.X

Multifocal contact lens design, not addition power, affects accommodation responses in young adult myopes

Publisher: Wiley

Date: 04-10-2021

DOI: 10.1111/OPO.12892

Abstract: Prolonged nearwork has been implicated in myopia progression. Accommodation responses of young‐adult myopes wearing different multifocal contact lenses were compared. Twenty adults, 18–25 years, with myopia (spherical equivalent refraction −0.50 to −5.50 D, mean −2.1 ± 1.6 D) wore five lens types in random order: Proclear single vision distance (SV), MiSight concentric dual‐focus +2.00 D Add (MS), Biofinity aspheric centre distance +1.50 D Add (CD1) and +2.50 D Add (CD2) (all Coopervision), and NaturalVue aspheric (Visioneering Technologies) (NVue). Using a Grand‐Seiko WAN‐5500 autorefractor with binocular correction and viewing right eye accommodative responses were measured after a 10 min adaptation period at 4.0, 1.0, 0.5, 0.33 and 0.25 m distances. Dynamic measurements were taken for 4 s at 6 Hz. Accommodative stimuli and responses were referenced to 4 m (i.e., refraction differences between 4 m and nearer distances). Accommodation lags and refraction instabilities (standard deviations of dynamic responses) were determined. For comparison, results were obtained for an absolute presbyopic eye, where trial lenses counteracted the accommodation stimulus. For SV and MS, accommodation responses were similar to the stimulus values. For aspheric lenses CD1, CD2 and NVue, accommodation responses were approximately 1.0 D lower across the stimulus range than with SV and MS, and rates of change were approximately 0.84 D per 1 D stimulus change. MS produced greater refraction instabilities than other lenses. For the presbyope, changes in refraction matched the trial lenses, indicating that corrections due to measurement through the different lenses were not needed. Reductions in accommodation response occurred in young myopes wearing aspheric multifocal contact lenses independent of the labelled ‘add’ power. The concentric dual‐focus MS lens produced minimal lags but had greater instability than the other lenses. The results indicate that the mechanism of multifocal contact lenses slowing myopia progression is unlikely to be through relaxing accommodation, at least in young adults.

Modified forms of Tscherning ellipses

Publisher: Wiley

Date: 20-02-2021

DOI: 10.1111/OPO.12771

Abstract: Third‐order equations are well known for determining sagittal and tangential powers of a thin lens, corresponding to an eye rotating behind a lens to view objects away from the optical axis of the lens. These equations are referenced to the back surface of the lens and do not take into account the peripheral thickness of the lens. They do not give the same results as finite raytracing at small angles in which powers are referenced to the vertex sphere, which is the same distance from the centre‐of‐rotation for all object angles. Modified forms of the third‐order sagittal and tangential image vergence error equations are developed to overcome the discrepancies. These are used to determine Tscherning ellipses for zero oblique astigmatism and zero mean oblique power error. While solutions to oblique astigmatism are not affected by the modifications, there are considerable changes to mean oblique error solutions.

Designing lenses to correct peripheral refractive errors of the eye

Publisher: Optica Publishing Group

Date: 2002

DOI: 10.1364/JOSAA.19.000010

Abstract: The purpose of this work was to design ophthalmic lenses that correct peripheral refractive errors of human eyes along a meridian. We designed lenses with the tangential section of one surface based on a figured spheroid but figured in the tangential section only. The curvature of the sagittal section of this surface was adjusted separately. A merit function was used to modify these surfaces until the lenses had power errors that corrected the eye. Ex les are presented of lenses that correct a schematic eye. They do excellent jobs of correcting the peripheral power errors of the eye and are relatively insensitive to small changes in fitting distance. We conclude that it is theoretically feasible to design lenses to correct peripheral refractive errors.

Impact of Forecasting Accuracy on Predictive Optimal Control of Active and Passive Building Thermal Storage Inventory

Publisher: Informa UK Limited

Date: 04-2004

DOI: 10.1080/10789669.2004.10391097

Higher order aberrations across the horizontal visual field

Publisher: SPIE-Intl Soc Optical Eng

Date: 2006

DOI: 10.1117/1.2209566

Abstract: The relationship between higher order aberrations and position in the horizontal visual field is investigated in normal and refractive corneal surgery subjects. In idual aberration coefficients are obtained from two studies using five untreated subjects and two myopic subjects following conventional laser assisted in situ keratomileusis (LASIK) surgery. Measurements are made out to 40 deg in the temporal and nasal visual fields. For the untreated subjects, horizontal coma is linearly influenced by position, and spherical aberration and secondary astigmatism are influenced quadratically by position (45 subjects). For the myopic LASIK subjects, the horizontal coma is opposite in sign from that for unoperated eyes at similar visual field positions, and this can be attributable largely to anterior corneal asphericity. Again, both spherical aberration and secondary astigmatism are influenced quadratically by position. To summarize, horizontal coma, spherical aberration, and secondary astigmatism change systemically across the horizontal visual field, and corneal asphericity has a major influence on the rate of change of coma and its sign.

Age-dependence of the average and equivalent refractive indices of the crystalline lens

Publisher: The Optical Society

Date: 02-12-2014

DOI: 10.1364/BOE.5.000031

Comment on: Determining specified IOL powers when silicone oil is to be used in the vitreous chamber

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-2023

DOI: 10.1097/J.JCRS.0000000000001291

Anterior Corneal, Posterior Corneal, and Lenticular Contributions to Ocular Aberrations

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 04-10-2016

DOI: 10.1167/IOVS.16-20067

Abstract: To determine the corneal surfaces and lens contributions to ocular aberrations. There were 61 healthy participants with ages ranging from 20 to 55 years and refractions -8.25 diopters (D) to +3.25 D. Anterior and posterior corneal topographies were obtained with an Oculus Pentacam, and ocular aberrations were obtained with an iTrace aberrometer. Raytracing through models of corneas provided total corneal and surface component aberrations for 5-mm-diameter pupils. Lenticular contributions were given as differences between ocular and corneal aberrations. Theoretical raytracing investigated influence of object distance on aberrations. Apart from defocus, the highest aberration coefficients were horizontal astigmatism, horizontal coma, and spherical aberration. Most correlations between lenticular and ocular parameters were positive and significant, with compensation of total corneal aberrations by lenticular aberrations for 5/12 coefficients. Anterior corneal aberrations were approximately three times higher than posterior corneal aberrations and usually had opposite signs. Corneal topographic centers were displaced from aberrometer pupil centers by 0.32 ± 0.19 mm nasally and 0.02 ± 0.16 mm inferiorly disregarding corneal decentration relative to pupil center was significant for oblique astigmatism, horizontal coma, and horizontal trefoil. An object at infinity, rather than at the image in the anterior cornea, gave incorrect aberration estimates of the posterior cornea. Corneal and lenticular aberration magnitudes are similar, and aberrations of the anterior corneal surface are approximately three times those of the posterior surface. Corneal decentration relative to pupil center has significant effects on oblique astigmatism, horizontal coma, and horizontal trefoil. When estimating component aberrations, it is important to use correct object/image conjugates and heights at surfaces.

Sensitivity of off‐axis performance of aspheric spectacle lenses to tilt and decentration

Publisher: Wiley

Date: 10-1993

DOI: 10.1111/J.1475-1313.1993.TB00502.X

Abstract: Apparatus was modified to measure, and theoretical raytracing was used to predict, off-axis powers of spectacle lenses in the presence of tilt or decentration. In response to poor fitting in the form of tilt or decentration, lenses with aspheric front surfaces were found to have greater off-axis power errors than best-form lenses with spherical surfaces. This is attributable to the aspheric lenses having flatter surfaces than the spherical lenses. The errors are up to twice those occurring for the spherical lenses, and can be quite high, e.g. 0.9 D astigmatism for +6D power with 10 degrees tilt in 20 degrees upgaze. Negative lenses are more sensitive to poor fitting than are positive lenses of the same power. The errors for straight ahead vision associated with tilt are approximately proportional to the square of the angle of tilt, and the errors for straight ahead vision associated with decentration are approximately proportional to the square of decentration. It is most important that aspheric lenses be correctly fitted, which means that each 2 degrees of pantascopic tilt should be accompanied by approximately 1 mm decentration.

Vision science and adaptive optics, the state of the field

Publisher: Elsevier BV

Date: 03-2017

DOI: 10.1016/J.VISRES.2017.01.006

Thomas Young's contribution to visual optics: The Bakerian lecture On the mechanism of the eye

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 15-10-2010

DOI: 10.1167/10.12.16

Abstract: Thomas Young (1773-1829) carried out major pioneering work in many different subjects. In 1800 he gave the Bakerian Lecture of the Royal Society on the topic of the "mechanism of the eye": this was published in the following year (T. Young, 1801). Young used his own design of optometer to measure refraction and accommodation, and discovered his own astigmatism. He considered the different possible origins of accommodation and confirmed that it was due to change in shape of the lens rather than to change in shape of the cornea or an increase in axial length. However, the paper also dealt with many other aspects of visual and ophthalmic optics, such as biometric parameters, peripheral refraction, longitudinal chromatic aberration, depth-of-focus and instrument myopia. These aspects of the paper have previously received little attention. We now give detailed consideration to these and other less-familiar features of Young's work and conclude that his studies remain relevant to many of the topics which currently engage visual scientists.

Experimental Study of Refraction Effects of Nominally Plano Ophthalmic Prisms and Magnifying Lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 02-2019

DOI: 10.1097/OPX.0000000000001334

Abstract: Nominally plano ophthalmic prisms give autorefraction results similar to those predicted on the basis of how effective powers change with pantoscopic tilt, and magnifying lenses give autorefraction results similar to those predicted on the basis of vergence changes. Without appreciation of the optics involved, these effects might wrongly be considered artifacts. The purpose of this study was to investigate the interactions of autorefractors with lenses and prisms. There were 15 adult participants across three experiments, with a range of ages and refractions. In experiments 1 and 2, participants wore frames containing base-up and base-down nominally plano prisms. In experiment 3, participants wore a lens that produced either 6.3% magnification or 5.9% minification, depending on which surface faced the eye. Autorefracting instruments with different operating principles were used: Shin-Nippon SRW5000 autorefractor, Grand Seiko 5100K autorefractor, Hoya AR-530 autorefractor, a Complete Ophthalmic Analysis System–High Definition wavefront sensor, and Tomey FC-800 autorefractor. A theory on the likely effects of magnifying lenses was presented. For ophthalmic prisms, refractions showed results similar to those predicted on the basis of how effective prism powers change with pantoscopic tilt. As tilt increased, base-up prism gave more positive mean refractions and more negative horizontal/vertical astigmatism and vice versa for base-down prisms. In the presence of 10° tilt, 8Δ base-up prisms and 8Δ base-down prisms had different effects by a mean of 0.36 diopters. Magnifying lenses affected refractions similar to those predicted on the basis of vergence changes, with 6% magnification and minification producing mean changes of −11 and +8%, respectively, in absolute mean refraction. There was no strong evidence that different instruments had different effects. The results have implications for studies in which prisms and lenses are placed in the front eyes, such as accommodation studies using thick lenses close to the eyes to stimulate accommodation rather than by changing object distance.

Influence of stop position on spectacle magnification

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 2014

DOI: 10.1097/OPX.0000000000000124

Influence of field size on pupil diameter under photopic and mesopic light levels

Publisher: Informa UK Limited

Date: 11-2011

DOI: 10.1111/J.1444-0938.2011.00636.X

Abstract: We investigated the interaction between adapting field size and luminance on pupil diameter when cones alone (photopic) or rods and cones (mesopic) were active. Circular achromatic targets (1° to 24° diameter) were presented to eight young participants on a rectangular projector screen. The accommodative influence on pupil diameter was minimised using cycloplegia in the foveally fixating right eye and the consensual pupillary reflex was measured in the left eye. Target luminance was adjusted for each stimulus such that corneal flux density (product of field area and luminance) was constant at 3,600 cd.deg(2) m(-2) (photopic condition) and 1.49 cd.deg(2) m(-2) (mesopic condition). There were no statistically significant effects of adaptive field size on pupil diameter for either condition. If corneal flux density is kept constant, there will be no change in pupil diameter as the size of the stimulus field increases at either mesopic or photopic lighting levels up to at least 24° diameter.

The Glenn A. Fry Award Lecture 2011: Peripheral optics of the human eye

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-2012

DOI: 10.1097/OPX.0B013E31825C3454

Relative peripheral hyperopia does not predict development and progression of myopia in children

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 23-09-2015

DOI: 10.1167/IOVS.15-17200

Abstract: To test the hypothesis that relative peripheral hyperopia predicts development and progression of myopia. Refraction along the horizontal visual field was measured under cycloplegia at visual field angles of 0°, ±15°, and ±30° at baseline, 1 and 2 years in over 1700 initially 7-year-old Chinese children, and at baseline and 1 year in over 1000 initially 14-year olds. One refraction classification for central refraction was "nonmyopia, myopia" (nM, M), consisting of nM greater than -0.50 diopters (D spherical equivalent) and M less than or equal to -0.50 D. A second classification was "hyperopia, emmetropia, low myopia, and moderate/high myopia" (H, E, LM, MM) with H greater than or equal to +1.00 D, E, -0.49 to +0.99 D, LM, -2.99 to -0.50 D, and MM less than or equal to -3.00 D. Subclassifications were made on the basis of development and progression of myopia over the 2 years. Changes in central refraction over time were determined for different groups, and relative peripheral refraction over time was compared between different subgroups. Simple linear regression of central refraction as a function of relative peripheral refraction did not predict myopia progression as relative peripheral refraction became more hyperopic: relative peripheral hyperopia and relative peripheral myopia predicted significant myopia progression for 0% and 35% of group/visual field angle combinations, respectively. Subgroups who developed myopia did not have more initial relative peripheral hyperopia than subgroups who did not develop myopia. Relative peripheral hyperopia does not predict development nor progression of myopia in children. This calls into question the efficacy of treatments that aim to slow progression of myopia in children by "treating" relative peripheral hyperopia.

Changes in straylight and corneal light scattering in a newly diagnosed case of type 2 diabetes

Publisher: Informa UK Limited

Date: 09-2015

DOI: 10.1111/CXO.12270

Perceptual compression of visual space during eye-head gaze shifts

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 06-10-2011

DOI: 10.1167/11.12.1

Abstract: In primates, inspection of a visual scene is typically interrupted by frequent gaze shifts, occurring at an average rate of three to five times per second. Perceptually, these gaze shifts are accompanied by a compression of visual space toward the saccade target, which may be attributed to an oculomotor signal that transiently influences visual processing. While previous studies of compression have focused exclusively on saccadic eye movements made with the head artificially immobilized, many brain structures involved in saccade generation also encode combined eye-head gaze shifts. Thus, in order to understand the interaction between gaze motor and visual signals, we studied perception during eye-head gaze shifts and found a powerful compression of visual space that was spatially directed toward the intended gaze (and not the eye movement) target location. This perceptual compression was nearly constant in duration across gaze shift litudes, suggesting that the signal that triggers compression is largely independent of the size and kinematics of the gaze shift. The spatial pattern of results could be captured by a model that involves interactions, on a logarithmic map of visual space, between two loci of neural activity that encode the gaze shift vector and visual stimulus position relative to the fovea.

Author Response: Gravity Affects Amplitude of Accommodation

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 06-09-2016

DOI: 10.1167/IOVS.16-20069

Author Response: Gravity Affects Lens Position During Accommodation

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 02-09-2016

DOI: 10.1167/IOVS.16-20068

Optical design of poly(methyl methacrylate) intraocular lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-1990

DOI: 10.1016/S0886-3350(13)80727-4

Abstract: The effect of poly(methyl methacrylate) intraocular lens shape on optical performance of pseudophakic eyes was investigated. Image quality criteria included wave aberrations, spot diagrams, longitudinal aberrations, the modulation transfer function, and an optimization procedure. For eyes with corneal asphericities encompassing most of the population, the optimum lens form for on-axis vision is close to plano-convex, with the more curved surface facing the cornea. This applies whether lenses are correctly centered, tilted, or decentered. For small off-axis angles, optimum lens shape varies with the ocular parameters. Good intraocular lens shapes range from the plano-convex to the equi-convex. Plano-convex lenses with the curved surface facing the retina are not recommended.

Change in human lens dimensions, lens refractive index distribution and ciliary body ring diameter with accommodation.

Publisher: The Optical Society

Date: 21-02-2018

DOI: 10.1364/BOE.9.001272

Vision in water

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 06-09-2013

DOI: 10.1167/13.11.4

Abstract: The purpose of this study is to determine visual performance in water, including the influence of pupil size. The water environment was simulated by placing goggles filled with saline in front of the eyes with apertures placed at the front of the goggles. Correction factors were determined for the different magnification under this condition in order to estimate vision in water. Experiments were conducted on letter visual acuity (seven participants), grating resolution (eight participants), and grating contrast sensitivity (one participant). For letter acuity, mean loss of vision in water, compared to corrected vision in air, varied between 1.1 log min of arc resolution (logMAR) for a 1 mm aperture to 2.2 logMAR for a 7 mm aperture. The vision in min of arc was described well by a linear relationship with pupil size. For grating acuity, mean loss varied between 1.1 logMAR for a 2 mm aperture to 1.2 logMAR for a 6 mm aperture. Contrast sensitivity for a 2 mm aperture deteriorated as spatial frequency increased with a 2 log unit loss by 3 c/°. Superimposed on this deterioration were depressions (notches) in sensitivity with the first three notches occurring at 0.45, 0.8, and 1.3 c/° with estimates for water of 0.39, 0.70, and 1.13 c/°. In conclusion, vision in water is poor. It becomes worse as pupil size increases, but the effects are much more marked for letter targets than for grating targets.

Effects of eye rotation and contact lens decentration on horizontal peripheral refraction

Publisher: Wiley

Date: 09-2019

DOI: 10.1111/OPO.12641

Abstract: Peripheral refraction is important in design of myopia control therapies. The aim was to investigate the influence of contact lens decentration associated with eye rotation on peripheral refraction in the horizontal visual field. Participants were 10 emmetropes and 10 myopes in good general and ocular health. Right eyes underwent cycloplegic peripheral refraction, using a Grand‐Seiko WAM ‐5500 Autorefractor, in 5° steps to ±35° eccentricities along the horizontal visual field. Targets were fixated using eye rotation only or head rotation only. Refractions were measured without correction and with three types of contact lenses: single vision, a multifocal centre‐distance aspheric with +2.50 D add and NaturalVue aspheric. Photographs of eyes during lens wear were taken for each eye rotation. Effects of visual field angle, lens type and test method (head or eye rotation) on vector components of relative peripheral refraction were evaluated using repeated measures anova s. Test method for each visual field angle/lens combination were compared via paired t ‐tests. Horizontal decentration ranges across the visual field were 1.2 ± 0.6 mm for single vision and 1.2 ± 0.4 mm for multifocal lenses but smaller at 0.7 ± 0.4 mm for NaturalVue lenses. There were only two significant effects of test method across the visual field angle/lens type combinations (single vision: for emmetropes horizontal/vertical astigmatism component at 35° nasal with mean difference −0.38 D and for myopes spherical equivalent refraction at 20° temporal with mean difference +0.24 D). Upon eye rotation the contact lenses decentred on the eye, but not enough to affect peripheral refraction. For the types assessed and for the horizontal visual field out to ±35° when measurements were performed with the Grand‐Seiko WAM ‐5500 autorefractor, it is valid to use eye rotations to investigate peripheral refraction.

Influence of Stiles–Crawford effect apodization on spatial visual performance

Publisher: Optica Publishing Group

Date: 09-1998

DOI: 10.1364/JOSAA.15.002545

Abstract: The Stiles-Crawford effect is often invoked by vision scientists when predictions of the effects of aberrations and defocus on spatial visual performance are not borne out experimentally. Modeling the Stiles-Crawford effect as an apodization, we investigated the expected influence that it would have on spatial visual performance in the presence of 1-diopter primary spherical aberration at the edge of a 6-mm-diameter centered pupil. The changes in refraction produced by a high Stiles-Crawford effect, according to various criteria, were small at approximately 0.10 diopter. The Stiles-Crawford effect has only a small capability to compensate for defocus and spherical aberration. These results indicate that the Stiles-Crawford effect has little influence on spatial visual performance in the case of centered pupils. We suggest that the faith that has often been placed in the Stiles-Crawford effect to account for discrepancies between experimental results and expected results is not justified, at least for well-centered pupils and Stiles-Crawford effects.

Influence of Gravity on Ocular Lens Position

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 15-04-2016

DOI: 10.1167/IOVS.15-18533

Abstract: We determined whether human ocular lens position is influenced by gravity. Anterior chamber depth (ACD) and lens thickness (LT) were determined with a Haag-Streit Lenstar LS900 for right eyes of participants in two age groups, with a young group of 13 participants aged 18 to 21 years (mean, 21 years SD, 1 year) and an older group of 10 participants aged 50 to 63 years (mean, 58 years SD, 4 years). There were two sessions for each participant separated by at least 48 hours, with one session for the usual upright head position and one session for a downwards head position. In a session, testing was done for minimum accommodation followed by testing at maximum accommodation. A drop of 2% pilocarpine nitrate was instilled, and testing was repeated after 30 minutes under minimum and maximum accommodation conditions. Gravity, manipulated through head posture, affected ACD for young adult and older adult groups but mean effects were only small, ranging from 0.04 to 0.12 mm, and for the older group required the instillation of an accommodation-stimulating drug. Gravity had a weakly significant effect on LT for the young group without accommodation or a drug, but the effect was small at 0.04 ± 0.06 mm (mean ± SD, P = 0.04). There is a small but real effect of gravity on crystalline lens position, manifested as reduction in ACD at high levels of accommodative effort with the head in a downwards position. This provides evidence of the ability of zonules to slacken during strong accommodation.

Validity of clinical measures of the AC/A ratio

Publisher: Informa UK Limited

Date: 1995

DOI: 10.1111/J.1444-0938.1995.TB00776.X

Aberrations associated with rigid contact lenses

Publisher: Optica Publishing Group

Date: 10-1995

DOI: 10.1364/JOSAA.12.002267

Abstract: A rigid contact lens on an eye can produce levels of spherical aberration very different from those produced by a spectacle lens in front of the eye. These levels are considerably affected by contact lens surface asphericity. Change in longitudinal spherical aberration associated with aspherizing a contact lens surface is well predicted by a simple equation for change in sagittal power of the surface. Displacing an aspheric contact lens on the eye can produce considerable defocus, which is well predicted by simple equations for change in sagittal and tangential surface powers. The best refractive correction with contact lenses can be determined only by overrefraction with a patient wearing a contact lens of power and characteristics similar to that which will be prescribed. An aspheric contact lens that moves to a considerable extent on the eye will cause more unstable vision than will a spherical lens that moves to the same extent.

Subjective blur limits for higher order aberrations

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-2010

DOI: 10.1097/OPX.0B013E3181F6FB99

Have We Misinterpreted the Study of Hoogerheide et al. (1971)?

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 08-2012

DOI: 10.1097/OPX.0B013E318264F2D1

Fixation Stability with Bessel Beams

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 02-2019

DOI: 10.1097/OPX.0000000000001328

Abstract: Ophthalmic imaging instruments that require stable fixation can benefit by using Bessel beams in the form of monitor-based Bessel images. The purpose of this study was to investigate fixation stability using laser Bessel and Gaussian beams and monitor-based images of these targets. The right eyes of 16 participants were presented with seven fixation targets: monitor-based images of a bull's eye/cross hair, a Gaussian beam, a Bessel beam with four rings and a Bessel beam with three rings laser Gaussian beam, laser Bessel beam with four rings, and laser Bessel beam with three rings. Participants fixated target centers for five runs, in which each run presented the seven targets for 20 seconds each. An Eye Tribe tracker s led eye positions at 30 Hz. Standard deviations along horizontal (σ x ) and vertical meridians (σ y ) and areas of bivariate contour ellipses (BCEAs) of fixation positions were calculated, and statistical significances of target differences for these parameters were determined. Average σ x , σ y , and BCEAs ranged from 0.26 to 0.35°, 0.38 to 0.55°, and 0.78 to 1.31 degrees 2 , respectively. Target differences in σ x (χ 2 6 = 13.0, P = .04), (σ y ) (χ 2 6 = 36.819, P .001), and BCEA (χ 2 6 = 34.406, P .001) were statistically significant. There were significant post hoc differences between some of the target pairs for σ y and BCEA, but not for σ x . Monitor-based Bessel beam targets provided significantly smaller σ y and BCEAs than the bull's eye/cross hair combination and the monitor- and laser-based Gaussian beam targets. Monitor-based images of Bessel beams provided better fixation targets than did a bull's eye/cross hair combination, monitor-based Gaussian images, and laser Gaussian beams, but no claim can be made that laser Bessel beams provide better fixation targets than do laser Gaussian beams. Monitor-based Bessel images should be useful for ophthalmic imaging instruments requiring stable fixation.

Observation of Gravitational Waves from Two Neutron Star–Black Hole Coalescences

Publisher: American Astronomical Society

Date: 29-06-2021

DOI: 10.3847/2041-8213/AC082E

Abstract: We report the observation of gravitational waves from two compact binary coalescences in LIGO’s and Virgo’s third observing run with properties consistent with neutron star–black hole (NSBH) binaries. The two events are named GW200105_162426 and GW200115_042309, abbreviated as GW200105 and GW200115 the first was observed by LIGO Livingston and Virgo and the second by all three LIGO–Virgo detectors. The source of GW200105 has component masses 8 . 9 − 1 . 5 + 1. 2 and 1. 9 − 0. 2 + 0. 3 M ⊙ , whereas the source of GW200115 has component masses 5. 7 − 2 . 1 + 1. 8 and 1. 5 − 0. 3 + 0. 7 M ⊙ (all measurements quoted at the 90% credible level). The probability that the secondary’s mass is below the maximal mass of a neutron star is 89%–96% and 87%–98%, respectively, for GW200105 and GW200115, with the ranges arising from different astrophysical assumptions. The source luminosity distances are 280 − 110 + 110 and 300 − 100 + 150 Mpc , respectively. The magnitude of the primary spin of GW200105 is less than 0.23 at the 90% credible level, and its orientation is unconstrained. For GW200115, the primary spin has a negative spin projection onto the orbital angular momentum at 88% probability. We are unable to constrain the spin or tidal deformation of the secondary component for either event. We infer an NSBH merger rate density of 45 − 33 + 75 Gpc − 3 yr − 1 when assuming that GW200105 and GW200115 are representative of the NSBH population or 130 − 69 + 112 Gpc − 3 yr − 1 under the assumption of a broader distribution of component masses.

Effect of orthokeratology on peripheral aberrations of the eye

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-2009

DOI: 10.1097/OPX.0B013E31819FA5AA

Optical design of low index intraocular lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-1991

DOI: 10.1016/S0886-3350(13)80825-5

Abstract: The effect of shape of low index (1.43) intraocular lenses on optical performance of pseudophakic eyes was investigated. A range of image quality criteria was used. The optimum lens for on-axis vision was biconvex, with the more curved surface facing the cornea. For small off-axis angles, optimum lens shape varied with the ocular parameters. A recommended range of intraocular lenses is plano-convex (with the curved shape facing the cornea) to equi-convex. Compared with conventional poly(methyl methacrylate) lenses (1.492 index), optimum lens shapes of low index lenses were less sensitive to changes in eye parameters and lens fitting position. The magnitudes of aberration of pseudophakic eyes varied more with changes in lens shape and lens position in low index lenses than in conventional lenses.

History of Visual Field Measurement

Publisher: Informa UK Limited

Date: 08-1979

DOI: 10.1111/J.1444-0938.1979.TB02329.X

Quantitative scoring of panel tests for assessment of colour vision in age related maculopathy

Publisher: Informa UK Limited

Date: 1991

DOI: 10.1111/J.1444-0938.1991.TB04600.X

Thomas Young's investigations in gradient-index optics

Publisher: No publisher found

Date: 2011

DOI: 10.1097/OPX.0B013E3182302EF6

Optical Design of Intraocular Lenses. I. On-Axis Performance

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 08-1989

DOI: 10.1097/00006324-198908000-00002

Abstract: The theoretical effect of intraocular lens shape on on-axis performance of model pseudophakic eyes was investigated. Image quality criteria included the magnitude of spherical aberration (both wave and longitudinal), spot diagrams, and the modulation transfer function. For eyes with corneal asphericities encompassing most of the population (Q greater than or equal to -0.5), the optimum lens form is close to being plano-convex, with the more curved surface facing the cornea.

The effectiveness of computer screen filters

Publisher: Informa UK Limited

Date: 05-1993

DOI: 10.1111/J.1444-0938.1993.TB05096.X

Theoretical Study of Refraction Effects of Plano Ophthalmic Prisms

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 2019

DOI: 10.1097/OPX.0000000000001321

Abstract: Nominally plano prisms can have appreciable refractive errors that exceed the usual prescribing step of 0.25 D, particularly when an eye rotates to view off-axis objects. The purpose of this study was to determine theoretically the refractive power effects of nominally plano-refracting power prisms. Plano prisms with zero refraction were designed for the as-worn condition. A basic method was developed to determine refractive effects in the presence of pantoscopic tilt. A refined method was developed that considers the eye rotating behind the lens, and this and the basic method were compared with accurate raytracing. Plano prisms of 4 and 8 Δ were designed with astigmatic back surfaces to compensate for oblique incidence, and tangential and sagittal image vergence errors were investigated for base-up (BU) and base-down (BD) directions, 0 and −3.33 D object vergences, and pantoscopic tilts up to 10°. Basic and refined results did not differ from accurate results by more than 0.04 and 0.08 D, respectively. Errors for 8 Δ prisms were approximately twice those for 4 Δ prisms. Errors were approximately proportional to tilt. With 10° tilt, the errors ranged between −0.65 D/−0.23 D (8 Δ BD, −3.33 D object vergence) and +0.36 D/+0.15 D (8 Δ BU, 0 D object vergence). Sagittal errors were generally about one third of corresponding tangential errors. In the presence of tilt, BU prisms had positive errors, and BD prisms had similar, but negative, errors for distance objects. At −3.33 D object vergence with tilt, negative errors for BD were greater than positive errors for BU. When the eye rotates to look at objects at different positions, errors can increase beyond those occurring on-axis. When designed for nontilted conditions, but then subjected to tilt or to viewing off-axis objects, plano prisms can have errors exceeding the usual prescribing step of 0.25 D.

Myopia and peripheral ocular aberrations

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 09-2009

DOI: 10.1167/9.10.15

EFFECT OF DEFOCUS ON VISUAL FIELD MEASUREMENT

Publisher: Wiley

Date: 07-1987

DOI: 10.1111/J.1475-1313.1987.TB00743.X

Predicting the effects of optical defocus on human contrast sensitivity

Publisher: Optica Publishing Group

Date: 09-1998

DOI: 10.1364/JOSAA.15.002536

Abstract: We used diffraction modulation transfer functions and model eyes to predict the effect of defocus on the contrast sensitivity function (CSF) and compared these predictions with previously published experimental data. Using the principle that optically induced changes in the modulation transfer function should be paralleled by identical changes in the CSF, we used the modulation transfer function calculations with the best-focus CSF measurements to predict the defocused CSF. An aberration-free model predicted the effects of defocus well when the CSF was measured with small pupils (e.g., 2 mm) but not with larger pupils (6-8 mm). When the model included average aberrations, prediction of the defocused CSF with large pupils was better but remained inaccurate, failing, in particular, to reflect differences between in idual subjects. Inclusion of measured aberrations for in idual subjects provided accurate predictions in the shape of the monochromatic CSF of two of three subjects with hyperopic defocus and good predictions of the polychromatic CSF of two subjects with hyperopic defocus. Prediction of the effects of myopic defocus by use of measured in idual aberrations of one subject were less successful. Hence a diffraction optics model can provide good predictions of the effects of defocus on the human CSF, given that one has knowledge of the in idual ocular aberrations. These predictions are dependent on the quality of the aberration measurements.

Peripheral monochromatic aberrations in young adult caucasian and East Asians

Publisher: OSA

Date: 2017

DOI: 10.1364/FIO.2017.JTU2A.116

Can partial coherence interferometry be used to determine retinal shape?

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-2011

DOI: 10.1097/OPX.0B013E318212AE56

Peripheral Refraction, Peripheral Eye Length, and Retinal Shape in Myopia.

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-2016

DOI: 10.1097/OPX.0000000000000905

Abstract: To investigate how peripheral refraction and peripheral eye length are related to retinal shape. Relative peripheral refraction (RPR) and relative peripheral eye length (RPEL) were determined in 36 young adults ( M +0.75D to −5.25D) along horizontal and vertical visual field meridians out to ±35° and ±30°, respectively. Retinal shape was determined in terms of vertex radius of curvature R v , asphericity Q , and equivalent radius of curvature R Eq using a partial coherence interferometry method involving peripheral eye lengths and model eye raytracing. Second-order polynomial fits were applied to RPR and RPEL as functions of visual field position. Linear regressions were determined for the fits’ second order coefficients and for retinal shape estimates as functions of central spherical refraction. Linear regressions investigated relationships of RPR and RPEL with retinal shape estimates. Peripheral refraction, peripheral eye lengths, and retinal shapes were significantly affected by meridian and refraction. More positive (hyperopic) relative peripheral refraction, more negative RPELs, and steeper retinas were found along the horizontal than along the vertical meridian and in myopes than in emmetropes. RPR and RPEL, as represented by their second-order fit coefficients, correlated significantly with retinal shape represented by R Eq . Effects of meridian and refraction on RPR and RPEL patterns are consistent with effects on retinal shape. Patterns derived from one of these predict the others: more positive (hyperopic) RPR predicts more negative RPEL and steeper retinas, more negative RPEL predicts more positive relative peripheral refraction and steeper retinas, and steeper retinas derived from peripheral eye lengths predict more positive RPR.

Dynamic Accommodation Responses to Stationary Colored Targets

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-2004

DOI: 10.1097/01.OPX.0000144749.73094.FD

Abstract: When the targets or the background in a display are different colors, longitudinal chromatic aberration ensures that there is no single correct accommodative response. The purpose of the present study was to determine whether the response becomes more variable when viewing certain multicolor displays. Accommodative responses of five young participants were measured with a dynamic infrared optometer while they viewed steady targets at a nominal stimulus level of 3 D. Target-on-background color combinations were black on white, black on blue, black on red, blue on red, red on blue, dark blue on red, and dark red on blue. When compared with the standard black-on-white target, responses to targets with reduced spectral bandwidth were not significantly more variable. In most participants, responses to near-isoluminant targets (e.g., red on blue and blue on red) were not more variable than to the standard target. However, calculated confidence intervals cannot rule out moderate to large changes in variability near isoluminance. Responses to these multicolor targets tended to favor the blue focus. In most in iduals, viewing multichromatic targets does not increase significantly the variation in accommodative response as compared with broadband black-and-white targets.

The optical modelling of the human lens

Publisher: Wiley

Date: 10-1991

DOI: 10.1111/J.1475-1313.1991.TB00237.X

Retinal image size in pseudophakia

Publisher: Wiley

Date: 24-08-2021

DOI: 10.1111/OPO.12874

Abstract: Approaches are developed to determine relative retinal magnifications in anisometropic patients undergoing cataract surgery these can be used to balance between full spectacle corrections with equal intraocular lens (IOL) powers and a pure IOL power correction. The analysis started from the original and pseudophakic Navarro eye models, where in the latter case an IOL replaced the natural lens. A third model was a simplified Navarro‐IOL model with a single surface cornea and a thin lens. These models were manipulated by altering vitreous length, corneal power and lens position. Retinal image sizes were determined for both full IOL corrections and full spectacle corrections by raytracing and approximate equations. Relative magnification ( RM ) was determined as the ratio of retinal image size of an eye to that of the appropriate standard eye. For raytracing and full IOL correction, vitreous length led to RM change of 5%/mm, while for corneal power and IOL position this was −0.4%/D and 1.4%/mm, respectively. For raytracing and spectacle correction, effects were 0%/D (vitreous depth), −1.6%/D (corneal power) and +1.0%/mm (IOL position). For full IOL correction, the approximate RM calculations were highly accurate. For spectacle correction, the approximate RM calculations were exact for vitreous length changes, reasonably accurate for corneal power changes but very inaccurate for changes in anterior chamber depth. Relative magnification approximations may be useful to assess the risk of aniseikonia in anisometropic patients targeted for postoperative emmetropia. Some of these patients would be corrected best by a combination of spectacles and IOLs.

Peripheral refraction in 7- and 14-year-old children in central China: The Anyang childhood eye study

Publisher: BMJ

Date: 04-11-2015

DOI: 10.1136/BJOPHTHALMOL-2014-305322

Abstract: To determine the distribution of peripheral refraction, including astigmatism, in 7- and 14-year-old Chinese children. 2134 7-year-old and 1780 14-year-old children were measured with cycloplegic central and horizontal peripheral refraction (15° and 30° at temporal and nasal visual fields). 7- and 14-year-old children included 9 and 594, respectively, with moderate and high myopia (≤-3.0 D), 259 and 831 with low myopia (-2.99 to -0.5 D), 1207 and 305 with emmetropia (-0.49 to +1.0 D), and 659 and 50 with hyperopia (>1.0 D), respectively. Myopic children had relative peripheral hyperopia while hyperopic and emmetropic children had relative peripheral myopia, with greater changes in relative peripheral refraction occurring in the nasal than the temporal visual field. The older group had the greater relative peripheral hyperopia and higher peripheral J180. Both age groups showed positive slopes of J45 across the visual field, with greater slopes in the older group. Myopic children in mainland China have relative peripheral hyperopia while hyperopic and emmetropic children have relative peripheral myopia. Significant differences exist between 7- and 14-year-old children, with the latter showing more relative peripheral hyperopia, greater rate of change in J45 across the visual field, and higher peripheral J180.

Refractive Errors Induced by Displacement of Intraocular Lenses within the Pseudophakic Eye

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-1989

DOI: 10.1097/00006324-198903000-00003

Abstract: Simple methods were developed to estimate refractive errors when intraocular lenses are not fitted optimally within pseudophakic eyes. The accuracy of these methods was determined by comparing results obtained with them to results obtained by raytracing through a model eye. Accuracy was good for longitudinal displacement and tilting, and reasonable for transverse displacement. Refractive errors are related linearly to the magnitude of the longitudinal displacement, and are related to the square of the magnitude of tilt or transverse displacement. The refractive error upon transverse displacement is quadratically dependent upon lens shape.

The Legal Persona of the Video Game

Publisher: SAGE Publications

Date: 30-03-2017

DOI: 10.1177/1743872117701204

Abstract: This article investigates Persona 4, a Japanese video game, as a complex retelling of the relationship of the subject to law. Through both narrative and medium, Persona 4 explores tensions of the legal subject as “persona ficta,” the imaginary identity that law uses to construct and bind subjects, demonstrating the inability of a player to let go of their fragmented identity even within a fictional setting. With the player and narrative relying on one another in a way that requires complicity to function, the player is forced to comply or not participate, a choice echoed in non-virtual life.

IMI – Clinical myopia control trials and instrumentation report

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 28-02-2019

DOI: 10.1167/IOVS.18-25955

Abstract: The evidence-basis based on existing myopia control trials along with the supporting academic literature were reviewed this informed recommendations on the outcomes suggested from clinical trials aimed at slowing myopia progression to show the effectiveness of treatments and the impact on patients. These outcomes were classified as primary (refractive error and/or axial length), secondary (patient reported outcomes and treatment compliance), and exploratory (peripheral refraction, accommodative changes, ocular alignment, pupil size, outdoor activity/lighting levels, anterior and posterior segment imaging, and tissue biomechanics). The currently available instrumentation, which the literature has shown to best achieve the primary and secondary outcomes, was reviewed and critiqued. Issues relating to study design and patient selection were also identified. These findings and consensus from the International Myopia Institute members led to final recommendations to inform future instrumentation development and to guide clinical trial protocols.

VDT screen reflections and accommodation response

Publisher: Wiley

Date: 04-1994

DOI: 10.1111/J.1475-1313.1994.TB00108.X

Abstract: Reflections in computer screens are imaged behind the screen and therefore potentially create a conflicting cue to appropriate accommodation response to the plane of screen. We investigated the effect of screen reflections on accommodation response by producing reflections (1.33 D accommodation demand) surrounding and overlying the fixation point (2 D accommodation demand) in the screen. We have found little evidence that reflections in visual display terminal screens can influence the accuracy of the users' accommodation responses under normal binocular viewing conditions. The accuracy of the accommodation response was not significantly influenced by the position of the reflections, the presence of surrounding text (peripheral cues), or the subjects' dark focus level. The variability of accommodation response did not significantly change under the various test conditions. However, accommodation errors were apparent to a small degree (< 0.25 D) under some monocular viewing conditions in the presence of screen reflections.

Visual field coordinates of pupillary circular axis and optical axis

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-2014

DOI: 10.1097/OPX.0000000000000228

Monochromatic Aberrations and Myopia

Publisher: Elsevier BV

Date: 05-1995

DOI: 10.1016/0042-6989(94)00236-F

Abstract: The monochromatic aberrations present in the eyes of a group of 21 young myopic subjects and 16 young emmetropic subjects were measured along the visual axis at three levels of accommodation. The aberrations were measured using a modified aberroscope technique which makes use of a retinal camera to photograph the shadow image of the aberroscope grid on the retina, while accommodation levels of 0, 1.5 and 3.0 D were induced consensually. Fourth-order aberrations were significantly different between the emmetropic and myopic groups, with the myopes showing lower fourth-order terms. A high proportion of the aberroscope grids photographed in the myopic eyes were too highly aberrated to permit analysis.

Comparing Methods to Estimate the Human Lens Power

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 07-10-2011

DOI: 10.1167/IOVS.11-7899

Abstract: PURPOSE. To compare the accuracy of different methods of calculating human lens power when lens thickness is not available. METHODS. Lens power was calculated by four Three methods were used with previously published biometry and refraction data of 184 emmetropic and myopic eyes of 184 subjects (age range, 18-63 years spherical equivalent range, -12.38 to +0.75 D). These three methods consist of the Bennett method, which uses lens thickness, a modification of the Stenström method and the Bennett-Rabbetts method, both of which do not require knowledge of lens thickness. These methods include c constants, which represent distances from lens surfaces to principal planes. Lens powers calculated with these methods were compared with those calculated using phakometry data available for a subgroup of 66 emmetropic eyes (66 subjects). RESULTS. Lens powers obtained from the Bennett method corresponded well with those obtained by phakometry for emmetropic eyes, although in idual differences up to 3.5 D occurred. Lens powers obtained from the modified-Stenström and Bennett-Rabbetts methods deviated significantly from those obtained with either the Bennett method or phakometry. Customizing the c constants improved this agreement, but applying these constants to the entire group gave mean lens power differences of 0.71 ± 0.56 D compared with the Bennett method: By further optimizing the c constants, the agreement with the Bennett method was within ±1 D for 95% of the eyes. CONCLUSIONS. With appropriate constants, the modified Stenström and Bennett-Rabbetts methods provide a good approximation of the Bennett lens power in emmetropic and myopic eyes.

Refraction and Aberration Across the Horizontal Central 10?? of the Visual Field

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-2006

DOI: 10.1097/01.OPX.0000214382.75847.C4

Psychological Perspectives of Virtual Child Sexual Abuse Material

Publisher: Springer Science and Business Media LLC

Date: 05-02-2021

DOI: 10.1007/S12119-021-09820-1

Optical models for human myopic eyes

Publisher: Elsevier BV

Date: 07-2006

DOI: 10.1016/J.VISRES.2006.01.004

Abstract: Data from the author's investigations and other studies are used to construct refractive dependent models. These models include a gradient index lens and aspheric corneal, lens and retinal surfaces. Elements that alter with refraction are anterior corneal radius, vitreous length and retinal shape (vertex radius of curvature and asphericity) and decentration. Two versions of the models are produced, one with centred and symmetrical optical elements, and one with tilts of the lens and decentrations and tilts of the retina. The centred model predicts increase in spherical aberration in myopia. It predicts the relative change in mean sphere in the periphery between the horizontal and vertical meridians that has been observed in a recent experimental study. It overestimates peripheral astigmatism by about 50%. The decentred version has limited success in predicting changes in peripheral refraction of average eyes.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO–Virgo Observing Run

Publisher: American Physical Society (APS)

Date: 16-06-2021

DOI: 10.1103/PHYSREVLETT.126.241102

First- and Third-Order Optical Theory of Gradient Index Materials, with Application to Contact Lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-1998

DOI: 10.1097/00006324-199811000-00026

Abstract: To investigate the feasibility of using gradient index media in contact lenses, we developed simple methods which we used to derive the power and aberrations associated with the contact lenses. In one method, we assume that the height of a ray does not change as it passes through the lens. We describe a second method in which the ray is assumed to follow a parabolic path as it passes through the lens. We use sophisticated third-order theory and finite raytracing for comparison with these methods. The methods are compared for contact lenses with parabolic radial gradient index media. Without the gradient index, these lenses would have zero power. The formula for power which assumes no change in ray height gives errors of approximally 0.8 and 1.5% for lenses of thicknesses 0.18 and 0.36 mm. However, the formula for third-order spherical aberration which uses the same assumption gives poor estimations. The method for calculating power using the parabolic ray path is very accurate. The sophisticated third-order aberration theory was reasonably accurate out to 2.5 mm ray height. The contact lenses with the gradient index media have much smaller aberration in air than do conventional contact lenses of the same powers, with the sign of the aberration being reversed. Our simple procedures give good estimations of powers of contact lenses with gradient index media. The approximate method, which assumes that the height of a ray does not change as it passes through the lens, should not be used for finding the spherical aberration of such a lens. Contact lenses with gradient index media have potential for minimizing spherical aberration.

Refractive indices used by the Haag‐Streit Lenstar to calculate axial biometric dimensions

Publisher: Wiley

Date: 23-12-2014

DOI: 10.1111/OPO.12182

Abstract: To estimate refractive indices used by the Lenstar biometer to translate measured optical path lengths into geometrical path lengths within the eye. Axial lengths of model eyes were determined using the IOLMaster and Lenstar biometers comparing those lengths gave an overall eye refractive index estimate for the Lenstar. Using the Lenstar Graphical User Interface, we noticed that boundaries between media could be manipulated and opposite changes in optical path lengths on either side of the boundary could be introduced. Those ratios were combined with the overall eye refractive index to estimate separate refractive indices. Furthermore, Haag-Streit provided us with a template to obtain 'air thicknesses' to compare with geometrical distances. The axial length estimates obtained using the IOLMaster and the Lenstar agreed to within 0.01 mm. Estimates of group refractive indices used in the Lenstar were 1.340, 1.341, 1.415, and 1.354 for cornea, aqueous, lens, and overall eye, respectively. Those refractive indices did not match those of schematic eyes, but were close in the cases of aqueous and lens. Linear equations relating air thicknesses to geometrical thicknesses were consistent with our findings. The Lenstar uses different refractive indices for different ocular media. Some of the refractive indices, such as that for the cornea, are not physiological therefore, it is likely that the calibrations in the instrument correspond to instrument-specific corrections and are not the real optical path lengths.

Astigmatism and its components in 12-year-old Chinese children: the Anyang Childhood Eye Study

Publisher: BMJ

Date: 02-08-2018

DOI: 10.1136/BJOPHTHALMOL-2018-312114

Abstract: To determine prevalence of refractive (RA), corneal (CA) and internal astigmatism (IA), including variation with gender and spherical equivalent refraction (SE), in a population of 12-year-old Chinese children. A total of 1783 students with a mean age of 12.7 years (range 10.0–15.6 years) completed comprehensive eye examinations in the Anyang Childhood Eye Study. Data of cycloplegic refraction and corneal curvature were analysed. Prevalences of RA, CA and IA ≥1.0 D were 17.4% (95%CI 15.6% to 19.2%), 52.8% (50.5% to 55.1%)%) and 20.9% (19.0% to 22.8%), respectively. With different limits of astigmatism axes classification, including ±15°, ±20° and ±30°, RA and CA axes were mainly ‘with-the-rule’ (WTR) (ie, correcting axis of negative cylinders at or near 180°), while those for IA axes were mainly ‘against-the-rule’ (ATR) (ie, correcting axis of negative cylinders at or near 90°). RA was not different between the genders, but girls had higher prevalence and greater means of CA and IA. RA and CA increased in students with higher ametropia (more myopia and more hyperopia) and were the highest in a high myopic group (SE≤−6 D), while IA was stable across refraction groups. Children with RA higher than 0.50 D were more likely to have lens corrections (51%, 57%, 61% and 69% for magnitudes of ≥0.50 D, ≥0.75 D, ≥1.0 D and ≥1.5 D, respectively). Prevalence of RA in the Chinese 12-year-old children was relatively high compared with other studies. RA and CA had mainly ‘WTR’ astigmatism, while IA was mainly ATR and partially compensated for CA. Girls had greater means and prevalences of CA and IA than did boys. Both RA and CA, but not IA, increased with refractive errors away from emmetropia.

Assessment ofAphkic Spectacle Lenses: High Power Flatback Lenses for ‐the Correction of Aphakia

Publisher: Informa UK Limited

Date: 11-1980

DOI: 10.1111/J.1444-0938.1980.TB02943.X

Longitudinal chromatic aberration as a function of refractive error

Publisher: Informa UK Limited

Date: 07-1993

DOI: 10.1111/J.1444-0938.1993.TB02956.X

Sunglasses, traffic signals, and color vision deficiencies

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 04-2009

DOI: 10.1097/OPX.0B013E318199D1DA

Pilot study: Effect of age on visual acuity with defocus and astigmatism

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2015

DOI: 10.1097/OPX.0000000000000459

Subjective blur limits for cylinder

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 08-2010

DOI: 10.1097/OPX.0B013E3181E61B8F

The use of colour difference vectors in diagnosing congenital colour vision deficiencies with the Farnsworth—Munsell 100‐hue test

Publisher: Wiley

Date: 1992

DOI: 10.1111/J.1475-1313.1992.TB00252.X

Three-dimensional MRI study of the relationship between eye dimensions, retinal shape and myopia

Publisher: The Optical Society

Date: 05-04-2017

DOI: 10.1364/BOE.8.002386

The Stiles–Crawford effect and subjective measurement of aberrations

Publisher: Elsevier BV

Date: 04-2002

DOI: 10.1016/S0042-6989(02)00028-7

Abstract: We considered the influence that the Stiles-Crawford effect (SCE) has on the measurement of subjective monochromatic and transverse aberration measurements. The SCE was measured with a two channel Maxwellian-viewing system. Transverse aberrations were measured using a vernier alignment technique in three subjects, with the natural SCE operating, with the SCE neutralised by filters optically conjugate with the eye's pupil, and for one subject with filters that shifted the SCE by more than 2 mm. As pupil diameter increased from 1 to 5 mm diameter, without the filters the slope of the transverse aberration versus position in the pupil decreased, e.g. for chromatic aberration this decreased by approximately 90%. The filters had little influence on transverse aberration. The results indicate that subjects do not use the centroid of the image of a blurred line target for alignment, but may rely very much on other cues.

Distribution of ocular biometry in 7- and 14-year-old Chinese children

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-2015

DOI: 10.1097/OPX.0000000000000570

Cone Ratios in Myopia and Emmetropia: A Pilot Study

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 2014

DOI: 10.1097/OPX.0000000000000450

Limitations and Precautions in the Use of the Farnsworth-Munsell Dichotomous D-15 Test

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-2019

DOI: 10.1097/OPX.0000000000001420

Abstract: Clinicians who administer the Farnsworth-Munsell D-15 test need to pay attention to the quality and quantity of lighting and the time that they allow for completion of the test, and all repeat attempts need to be included in reports on compliance with color vision standards. The validity of the Farnsworth-Munsell D-15 has been questioned because practice may allow significantly color vision–deficient subjects to pass. In this article, we review the influence of practice and other factors that may affect the performance. These relate to both the design and the administration of the test. We review the literature and present some calculations on limitations in the colorimetric design of the test, quantity and quality of lighting, time taken, and repeat attempts. In addition to the review of the literature, color differences and luminance differences under selected sources are calculated, and the increases in luminance clues under some sources and for protanopes are illustrated. All these factors affect the outcome of the test and need specification and implementation if the test is to be applied consistently and equitably. We recommend the following: practitioners should never rely on a single color vision test regardless of the color vision standard lighting should be T cp ′′ 6500 K and R a 90 illuminance levels should be between 200 and 300 lux if detection of color vision deficiency is a priority or between 300 and 1000 lux if the need is to test at the level where illuminance has minimal influence on performance illuminance should be reported time limits should be set between 1 and 2 minutes repeat testing (beyond the specified test and one retest) should be carried out only with authorization and initial and repeated results should be reported. A set of test instructions to assist in the consistent application of the test is provided in the Appendix.

Quantitative Scoring Methods for D15 Panel Tests in the Diagnosis of Congenital Color Vision Deficiencies

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 1991

DOI: 10.1097/00006324-199101000-00007

Abstract: Farnsworth's standard D15 and L'Anthony's desaturated D15 panel tests were administered to 99 congenital red-green color defective subjects. The results were analyzed in three ways: (1) by summing the color differences between adjacent caps according to Bowman, (2) by averaging color difference vectors (CDV) according to Vingrys and King-Smith, and (3) by visually inspecting and counting the crossings. The Bowman measure was highly correlated with one of the CDV measures but provides less information regarding a cap arrangement. The desaturated D15 test can be expected to misclassify 5% of dichromats by type (protan/deutan) compared to a type misclassification rate of less than 0.1% for the D15 panel test. The correct diagnostic rates for type were 45% for the standard D15 test and 58% for the desaturated D15 test. However, the improvement in correct diagnostic rate for the latter test was accompanied by an increase in the misdiagnostic rate from 2 to 10%. The main value of the desaturated D15 test in congenital color vision diagnosis would seem to be in providing classification of those subjects who pass the standard D15 test. Quantitative scoring of the tests provides a good estimate of severity of defect. Visual inspection provides a similar diagnostic rate to CDV analysis, but has a lower type misdiagnostic rate at the desaturated D15 test and is more likely to be correct when the two methods disagree. We suggest that quantitative scoring techniques are of limited benefit for the clinical diagnosis of congenital color vision defects but that they are of use in clinical trials or for the monitoring of changes in color vision over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Specifying peripheral aberrations in visual science

Publisher: SPIE-Intl Soc Optical Eng

Date: 2012

DOI: 10.1117/1.JBO.17.2.025004

Erratum

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 11-2003

DOI: 10.1097/00006324-200311000-00016

Calculation of Extra Curve of Negative Lenticular Spectacle Lenses

Publisher: Informa UK Limited

Date: 03-1985

DOI: 10.1111/J.1444-0938.1985.TB00746.X

Optimal spherical focus in the peripheral retina

Publisher: Wiley

Date: 18-04-2008

DOI: 10.1111/J.1475-1313.2008.00552.X

Abstract: It is well known that, in most eyes, astigmatism increases with the field angle. A simple reduced-eye model is used to demonstrate that, for point imagery in the peripheral retina, the combination of oblique astigmatism with elliptical entrance and exit pupils means that the retinal image with the optimal rotational symmetry is not necessarily at a focus corresponding to a 'best-sphere' correction. Equations are derived for the position of focus at which a circularly symmetric blur patch is obtained and for the dimensions of the patch in this and other image planes. Ray tracing through a wide-angle schematic eye is used to explore the validity of the simple model. It is shown that although the latter gives good predictions of retinal imagery for very small entrance pupils, it becomes less valid for larger, more realistic pupil diameters, due to the increasing importance of the effects of higher-order aberrations. Nevertheless, the simple model can still yield useful insights into through-focus, peripheral optical imagery.

The Effect of Pupil Size on Visual Acuity in Uncorrected and Corrected Myopia

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-1979

DOI: 10.1097/00006324-197905000-00006

Abstract: The effect of pupil size on the relation between Snellen visual acuity and corrected and uncorrected myopia was examined for 22 young subjects with degrees of myopia ranging from 0.75 D to 7.5 D. Effective pupil size was varied by inducing mydriasis and then placing artificial pupils of between 1.0 and 8.0 mm diameter before the eye. Both a constant chart luminance of 120 cd/m2 and a constant retinal illuminance of 2150 trolands were used. There was little difference in results for the two lighting conditions. For the corrected myopes considered as a group, maximum visual acuity occurred for 2--3 mm diameter pupils, but larger pupils reduced acuity only marginally. For the uncorrected myopes, variation in pupil size produced a large variation in visual acuity, and for refractive errors greater than about 1.5 D, the optimum pupil diameter was less than 1 mm. For uncorrected myopes of 3.0 D or less, visual acuity was nearly as good with a 1-mm pupil as for corrected myopes. The presented data are a useful guide to the clinician.

THIRD‐ORDER THEORY AND ASPHERIC SPECTACLE LENS DESIGN

Publisher: Wiley

Date: 04-1984

DOI: 10.1111/J.1475-1313.1984.TB00353.X

Explanation of the Lens Paradox

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2002

DOI: 10.1097/00006324-200203000-00008

Applying SLODAR to measure aberrations in the eye

Publisher: Optica Publishing Group

Date: 06-05-2008

DOI: 10.1364/OE.16.007309

Abstract: As a proof of concept we apply a technique called SLODAR as implemented in astronomy to the human eye. The technique uses single exposures of angularly separated "stars" on a Hartmann-Shack sensor to determine a profile of aberration strength localised in altitude in astronomy, or path length into the eye in our application. We report on the success of this process with both model and real human eyes. There are similarities and significant differences between the astronomy and vision applications.

Anterior corneal and internal contributions to peripheral aberrations of human eyes

Publisher: Optica Publishing Group

Date: 03-2004

DOI: 10.1364/JOSAA.21.000355

Abstract: Anterior corneal and internal component contributions to overall peripheral aberrations of five human eyes were determined, based on corneal topography and overall aberration measurements. Anterior corneal position and orientation (tilt) were referenced to the line of sight. Ray tracing was performed through the anterior cornea for 6-mm-diameter pupils at angles out to 40 degrees in both the temporal and the nasal visual fields. In general, both component and overall Zernike aberrations were greater for the nasal than for the temporal visual field. In general, the anterior corneal aberration components were considerably higher than the overall aberrations across the visual field and were balanced to a considerable degree by the internal ocular aberration components. The component and overall levels of Zernike third-order aberrations showed linear trends away from the fixation axis, and the component levels of Zernike fourth-order aberrations showed quadratic trends away from the fixation axis. The second-order, but not higher-order, aberration components were susceptible to the choice of image radius of curvature, while disregarding corneal position and orientation affected second- and higher-order aberration components.

Accommodation lags are higher in myopia than in emmetropia: Measurement methods and metrics matter

Publisher: Wiley

Date: 07-2022

DOI: 10.1111/OPO.13021

Abstract: To determine whether accommodative errors in emmetropes and myopes are systematically different, and the effect of using different instruments and metrics. Seventy‐six adults aged 18–27 years comprising 24 emmetropes (spherical equivalent refraction of the dominant eye +0.04 ± 0.03 D) and 52 myopes (−2.73 ± 0.22 D) were included. Accommodation responses were measured with a Grand Seiko WAM‐5500 and a Hartmann–Shack Complete Ophthalmic Analysis System aberrometer, using pupil plane (Zernike and Seidel refraction) and retinal image plane (neural sharpness—NS and visual Strehl ratio for modulation transfer function—VSMTF) metrics at 40, 33 and 25 cm. Accommodation stimuli were presented to the corrected dominant eye, and responses, referenced to the corneal plane, were determined in the fellow eye. Linear mixed‐effects models were used to determine influence of the refractive group, the measurement method, accommodation stimulus, age, race, parental myopia, gender and binocular measures of heterophoria, accommodative convergence/accommodation and convergence accommodation/convergence ratios. Lags of accommodation were affected significantly by the measurement method ( p 0.001), the refractive group ( p = 0.003), near heterophoria ( p = 0.002) and accommodative stimulus ( p 0.05), with significant interactions between some of these variables. Overall, emmetropes had smaller lags of accommodation than myopes with respective means ± standard errors of 0.31 ± 0.08 D and 0.61 ± 0.06 D ( p = 0.003). Lags were largest for the Grand Seiko and Zernike defocus, intermediate for NS and VSMTF, and least for Seidel defocus. The mean lag of accommodation in emmetropes is approximately equal to the previously reported depth of focus. Myopes had larger (double) lags than emmetropes. Differences between methods and instruments could be as great as 0.50 D, and this must be considered when comparing studies and outcomes. Accommodative lag increased with the accommodation stimulus, but only for methods using a fixed small pupil diameter.

Clinical Trial with Commercial Aspheric Aphakic Lenses

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 09-1984

DOI: 10.1097/00006324-198409000-00006

Abstract: A clinical trial with 11 subjects was conducted to compare the Armorlite Multiple Drop, the Signet Hyperaspheric, the Sola Hi-Drop, and the American Optical Fulvue types of aspheric aphakic lenses. Reasonable off-axis visual acuities were obtained with the Signet, Sola, and Fulvue types, but poor visual acuities were found with the Armorlite type. Similar visual field limits were found with the armorlite, Signet, and Sola types. Considerably larger limits were found with the Fulvue type than with the other types. However, subjects failed to appreciate these larger limits this was attributed to the extremely poor image quality near the edge of the visual field with this lens type. Some subjects disliked the poor off-axis image quality with the Armorlite lens type, and it had poor acceptance relative to the other types. Concerning subjective perception of weight, cosmetic appearance, and visual field size, and subjective evaluation of performance of everyday activities, there were no significant differences between lens types. It was concluded that reducing lens off-axis power errors, corresponding to the rotating eye, should remain the most important principle of aphakic spectacle lens design.

George Smith 1941-2008. Associate professor in the Department of Optometry and Vision Sciences, The University of Melbourne.

Publisher: Informa UK Limited

Date: 05-2008

DOI: 10.1111/J.1444-0938.2008.00262.X

Age-related paraxial schematic emmetropic eyes

Publisher: Wiley

Date: 22-12-2009

DOI: 10.1111/J.1475-1313.2008.00598.X

Abstract: Based on recent biometric data, four-surface paraxial schematic emmetropic eyes for different ages have been developed. There are three sets of schematic eyes: male, female and overall. With increase in age, the changes in the schematic eyes are decreased anterior chamber depth, increased lens thickness, decreased vitreous length, increased axial length, decreased anterior lens radius of curvature and increased lens equivalent refractive index. Gender differences are greater anterior corneal radii of curvature (0.07 mm), longer vitreous chambers (0.70 mm), longer axial length (0.70 mm) and lower lens equivalent refractive indices of male eyes (0.007) relative to female eyes. Gaussian parameters of the various schematic eyes are given.

The Alteration in Static Perimeter Thresholds Caused by the Prismatic Effect of Ophthalmic Lenses

Publisher: Informa UK Limited

Date: 07-1979

DOI: 10.1111/J.1444-0938.1979.TB02311.X

Subjective measurement of the Stiles-Crawford effect of the first kind with variation in accommodation.

Publisher: Wiley

Date: 13-08-2021

DOI: 10.1111/OPO.12855

Abstract: To measure the Stiles-Crawford effect of the first kind (SCE-I), corresponding to central vision, with innovative technology to evaluate changes in the directionality and photoreceptor alignment with accommodation. A uniaxial Maxwellian system (spot size in pupil 0.5 mm diameter) was employed, incorporating a spatial light modulator to flicker at 2 Hz between two 2.3° fields corresponding to test (peripheral pupil) and reference (pupil centre) positions. Participants determined thresholds at 13 positions along the horizontal pupil meridian by indicating if the test field was brighter or dimmer than the reference field. Thresholds were determined by a staircase procedure after four reversals at each pupil location. After pupil dilation, seven emmetropes were tested at 0 D to 6 D accommodation stimulus levels in 2 D intervals. Data were fit by the Gaussian function, both when the fits were unforced or forced to pass through the sensitivity expected for the reference point. Directionality (ρ) and peak location values Regression slopes for ρ as a function of accommodation stimulus were not significant. There was a tendency for Directionality did not change with accommodation, but the pupil peak location showed a significant temporal shift of approximately 0.62 mm with 6 D accommodation stimulus. It is possible that substantial changes in the directionality and a shift in the direction of peak location might occur at very high levels of accommodation.

Neural and optical limits to visual performance in myopia

Publisher: Elsevier BV

Date: 10-2006

DOI: 10.1016/J.VISRES.2006.05.005

Abstract: We investigated the relative importance of neural and optical limitations to visual performance in myopia. A number of visual performance measures were made on all or subsets of 121 eyes of emmetropic and myopic volunteers aged 17-35 years. These tests included visual measures that are mainly neurally limited (spatial summation out to +/-30 degrees in the horizontal visual field and resolution acuity out to +/-10 degrees in the horizontal visual field) and central ocular aberrations. We found that myopia affected the neurally limited tests, but had little effect on central higher order aberration. The critical area for spatial summation increased in the temporal visual field at 0.03 log units/dioptre of myopia. Resolution acuity decreased at approximately 0.012 log units/dioptre of myopia. Losses of visual function were slightly greater in the temporal than in the nasal visual field. The observed visual deficit in myopia can be explained by either global retinal expansion with some post-receptor loss (e.g. ganglion cell death) or a posterior polar expansion in which the point about which expansion occurs is near the centre of the previously emmetropic globe.

Continuous gradient index and shell models of the human lens

Publisher: Elsevier BV

Date: 09-1995

DOI: 10.1016/0042-6989(95)00019-V

Abstract: Because of the complexity of tracing rays through a gradient refractive index medium, the human eye's lens is sometimes approximated by a shell structure with constant refractive index within shells. In the shell model, power arises from a combination of an axial variation in index and the curvatures of the shell surfaces. We develop an equation which gives the power due to the gradient index of the lens, and use this to choose shell models that have the same power as the continuous gradient index model. Some types of shell models are described and evaluated.

Modern Optical Design Assessment and Spectacle Lenses

Publisher: Informa UK Limited

Date: 05-1985

DOI: 10.1080/713821761

The effects of optically and digitally simulated aniseikonia on stereopsis

Publisher: Wiley

Date: 06-03-2022

DOI: 10.1111/OPO.12973

Abstract: To simulate both lens‐induced and screen‐induced aniseikonia, and to assess its influence on stereopsis. Additionally, to determine if screen‐based size differences could neutralise the effects of lens‐induced aniseikonia. A four‐circle (4‐C) paradigm was developed, where one circle appears in front or behind the others because of crossed or uncrossed disparity. This stereotest was used for three investigations: (1) Comparison with the McGill modified random dot stereogram (RDS), with anisometropia introduced with +2 D spheres and cylinders, and with aniseikonia introduced with 6% overall and 6% meridional (×180, ×90) magnifiers before the right eye (2) Comparison of lens‐induced and screen‐induced 6% overall and meridional magnifications and (3) Determining if lens and screen effects neutralised, by opposing 6% lens‐induced magnification to the right eye with screen‐inducements of either 6% left eye magnification or 6% right eye minification. A pilot study of the effect of masking versus not masking the surround was also conducted. The 4‐C test gave higher stereo‐thresholds than the RDS test by 0.5 ± 0.2 log units across both anisometropic and aniseikonic conditions. However, variations in power, meridian and magnification affected the two tests similarly. The pilot study indicated that surround masking improved neutralisation of screen and lens effects. With masking, lens‐induced and screen‐induced magnifications increased stereo‐thresholds similarly. With lens and screen effects opposed, for most participants stereo‐thresholds returned to baseline for overall and ×180 magnifications, but not for ×90 magnification. Only three of seven participants showed good compensation for ×90 magnification. Effects of lens‐induced aniseikonia on stereopsis cannot always be successfully simulated with a screen‐based method. The ability to neutralise refractive aniseikonia using a computer‐based method, which is the basis of digital clinical measurement, was reasonably successful for overall and ×180 meridional aniseikonia, but not very successful for ×90 aniseikonia.

The Use of Technology by Gold Coast Legal Practitioners

Publisher: Queensland University of Technology

Date: 31-01-2020

DOI: 10.5204/LTHJ.V2I1.1304

Abstract: Digital technology is inexorably changing the landscape of law. From the adoption of sustaining technologies, which enhance the productivity and efficiency of the traditional law firm, to the creation of disruptive technologies, which fundamentally challenge the established forms of the legal profession, the digitalisation of the legal sphere opens up new spaces and structures of legal practice that challenge the form of traditional law firms. Existing literature on the digitalisation of law paints a narrative of technological resistance by traditional law firms, suggesting that BigLaw firms are defensive of the power and status that the current model affords them. However, in reality, the wealth and expanse of BigLaw firms allow them to freely invest in and create new technological innovations. Recent Australian research places BigLaw firms at the forefront of adopting digital technologies into the legal market, leaving behind small and medium-sized legal firms as the victims of digital disruption rather than as technological adopters or beneficiaries. This article stands in contrast to the literature on traditional small and medium-sized firms, arguing that lawyers from such firms in Australia are not only embracing the use of technology but are also actively engaging in the digital transformation of legal practice. It presents qualitative findings from a 2018 study that involved open-ended interviews with nine lawyers from the Gold Coast, Australia on their use and adoption of digital technologies in their professional legal practice. Through unpacking these findings, this article demonstrates a new perspective of small and medium-sized traditional legal firms in which they do not resist law’s digital future but instead embrace it.

Assessment of the accuracy of the crossed-cylinder aberroscope technique

Publisher: Optica Publishing Group

Date: 09-1998

DOI: 10.1364/JOSAA.15.002477

Abstract: Simulations of the optics of the Howland crossed-cylinder aberroscope technique show that errors in alignment, data collection, and analysis can lead to unexpected asymmetries of the determined aberrations in a rotationally symmetric system. In particular, coma can be incorrectly indicated. The magnitude of the error in aberration measurement depends on the magnitude of the alignment, data collection, and alignment errors. These findings indicate that the tolerances for setting up the technique and data collection should be analyzed thoroughly before quantitative significance is given to the determined aberration coefficients.

Influence of Stiles–Crawford effect apodization on spatial visual performance with decentered pupils

Publisher: Optica Publishing Group

Date: 06-2001

DOI: 10.1364/JOSAA.18.001201

Abstract: Using theoretical estimates of the optical-transfer function and line-spread function as image-quality criteria, we predicted the influence of the Stiles-Crawford effect (SCE) on both optical performance of the eye and subjective measurements of transverse aberrations when pupils are decentered. The SCE was modeled as a pupil apodization. The SCE appears to improve image quality by providing compensation for aberrations induced by pupil decentration, but this improvement is usually small. When a criterion of the placement of the image is used as the centroid of the line-spread function, an average SCE reduces the influence of pupil decentration on subjective transverse chromatic aberrations (TCA's) for 5-mm-diameter pupils by 30%. This reduction is much less than that obtained by previous experimental studies of TCA, and possible reasons for this discrepancy are discussed. Decentering the SCE produces an appreciable shift in subjective TCA for 5-mm-diameter pupils of 1.4 arc min per 1-mm decentration (at wavelengths 433 and 622 nm).

Thomas young's investigations in gradient-index optics

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 05-2011

DOI: 10.1097/OPX.0B013E31821177B2

Visual acuity with astigmatic blur

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 07-2011

DOI: 10.1097/OPX.0B013E3182186BC4

Low levels of refractive blur increase the risk of colour misperception of red train signals.

Publisher: Wiley

Date: 02-04-2022

DOI: 10.1111/OPO.12979

Abstract: Red signals signify danger in a range of situations, including train operations. Importantly, misperception of a red signal as yellow can have serious safety implications. This study investigated the effects of lens blur on incorrect colour perception of red signals, which has been implicated in previous train crashes. Participants included 15 young (26.6 ± 4.6 years) and 15 older (55.8 ± 3.1 years) visually normal adults. Red and yellow wayside train signals were simulated for two brightness levels (dim, bright) using a custom-built projection system. The effect of blur (best-corrected refraction [No Blur], +0.25 DS, +0.50 DS, +0.75 DS, +1.00 DS, +1.25 DS) on the number of incorrect colour perception responses of the signals was recorded. The order of conditions was randomised between participants. For incorrect responses to the red signal, there were significant main effects of blur (p < 0.001) and signal brightness (p < 0.001) and a significant interaction between blur and brightness (p < 0.001). The effects of blur were greater for the dim compared to the bright signals, with significantly higher colour misperceptions for the dim signal for +0.50 DS blur and higher, compared with No Blur. Colour misperceptions of the yellow signals were low compared with that of the red signals, with only +1.25 DS blur resulting in a significantly higher number of incorrect responses than No Blur (p 0.19). Low levels of blur (+0.50 DS to +1.25 DS) resulted in a significant misperception of the red signals as orange-yellow, particularly for dim signals. The findings have implications for vision testing and refractive correction of train drivers to minimise the possibility of colour misperception of red train signals.

Repeatability and Comparison of Peripheral Eye Lengths With Two Instruments

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-2013

DOI: 10.1097/OPX.0B013E318282CCC4

Peripheral detection and resolution with mid-/long-wavelength and short-wavelength sensitive cone systems

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 31-08-2016

DOI: 10.1167/16.10.21

Abstract: This study compared neural resolution and detection limits of the human mid-/long-wavelength and short-wavelength cone systems with anatomical estimates of photoreceptor and retinal ganglion cell spacings and sizes. Detection and resolution limits were measured from central fixation out to 35° eccentricity across the horizontal visual field using a modified Lotmar interferometer. The mid-/long-wavelength cone system was studied using a green (550 nm) test stimulus to which S-cones have low sensitivity. To bias resolution and detection to the short-wavelength cone system, a blue (450 nm) test stimulus was presented against a bright yellow background that desensitized the M- and L-cones. Participants were three trichromatic males with normal visual functions. With green stimuli, resolution showed a steep central-peripheral gradient that was similar between participants, whereas the detection gradient was shallower and patterns were different between participants. Detection and resolution with blue stimuli were poorer than for green stimuli. The detection of blue stimuli was superior to resolution across the horizontal visual field and the patterns were different between participants. The mid-/long-wavelength cone system's resolution is limited by midget ganglion cell spacing and its detection is limited by the size of the M- and L-cone photoreceptors, consistent with previous observations. We found that no such simple relationships occur for the short-wavelength cone system between resolution and the bistratified ganglion cell spacing, nor between detection and the S-cone photoreceptor sizes.

Optical models of the human eye

Publisher: Informa UK Limited

Date: 03-2016

DOI: 10.1111/CXO.12352

Abstract: Optical models of the human eye have been used in visual science for purposes such as providing a framework for explaining optical phenomena in vision, for predicting how refraction and aberrations are affected by change in ocular biometry and as computational tools for exploring the limitations imposed on vision by the optical system of the eye. We address the issue of what is understood by optical model eyes, discussing the 'encyclopaedia' and 'toy train' approaches to modelling. An extensive list of purposes of models is provided. We discuss many of the theoretical types of optical models (also schematic eyes) of varying anatomical accuracy, including single, three and four refracting surface variants. We cover the models with lens structure in the form of nested shells and gradient index. Many optical eye models give accurate predictions only for small angles and small fields of view. If aberrations and image quality are important to consider, such 'paraxial' model eyes must be replaced by 'finite model' eyes incorporating features such as aspheric surfaces, tilts and decentrations, wavelength-dependent media and curved retinas. Many optical model eyes are population averages and must become adaptable to account for age, gender, ethnicity, refractive error and accommodation. They can also be customised for the in idual when extensive ocular biometry and optical performance data are available. We consider which optical model should be used for a particular purpose, adhering to the principle that the best model is the simplest fit for the task. We provide a glimpse into the future of optical models of the human eye. This review is interwoven with historical developments, highlighting the important people who have contributed so richly to our understanding of visual optics.

Peripheral refraction patterns out to large field angles

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 02-2013

DOI: 10.1097/OPX.0B013E31827F1583

Biometry of eyes in type 1 diabetes

Publisher: The Optical Society

Date: 04-02-2015

DOI: 10.1364/BOE.6.000702

Digital holographic microscope for human eye retinal structures recording in vivo

Publisher: Optica Publishing Group

Date: 17-11-2021

DOI: 10.1364/AO.403532

Abstract: We introduce the digital holographic microscope for recording in vivo human eye retinal structures. Current eye imaging technologies cannot provide images with resolutions better than 1 µm within depths of a few hundred micrometers. This can be improved with digital holography, in which a hologram of the eye captured with digital camera contains information about structures over the full depth of the eye. This information can be reconstructed either optically or numerically. Our hologram recording scheme utilizes working principles of the off-axis digital holographic microscope, designed for reflective micro-object investigation. The eye cornea and lens form the microscope objective. We can record in vivo digital holograms of the human eye retina with resolution after reconstruction of at least 1.3 micrometer.

Relationship between retinal distance and object field angles for finite schematic eyes

Publisher: Wiley

Date: 19-05-2016

DOI: 10.1111/OPO.12284

Abstract: Retinal anatomical studies have used the Drasdo & Fowler three-refracting surface schematic eye to convert between retinal distances and object field angles. We compared its performance at this task with those of more sophisticated four-refracting surface schematic eyes. Raytracing was performed for Drasdo & Fowler, Lotmar, Navarro, Liou & Brennan, Kooijman and Atchison schematic eyes, and some of their variants. The Drasdo & Fowler eye gives a greater rate of change of object field angle with retinal distance at the retinal centre of about 5% than the other schematic eyes. This rate of change also increases much more quickly into the peripheral retina for the Drasdo & Fowler eye than for the other eyes. The reason for these differences is only that the Drasdo & Fowler eye is shorter than the other eyes. The relationship between retinal distance and visual field angle appears robust to changes in retinal radius of curvature when the retina is spherical. The retinal asphericity of Kooijman and Atchison eyes appears to play a role beyond 14 mm (~50°). Changing the length of the Drasdo & Fowler eye, to match those of the four-refracting surface schematic eyes, gives similar relationships between retinal distance and object field angle up to a retinal distance of approximately 14 mm (~50°). The relationship will change with refractive error as this is related to axial length and to retinal shape, and this should be taken into consideration for accurate conversions. For distances and angles beyond 14 mm and ~50°, retinal shape should be taken into account.

Changes in through-focus spatial visual performance with adaptive optics correction of monochromatic aberrations

Publisher: Elsevier BV

Date: 08-2008

DOI: 10.1016/J.VISRES.2008.04.033

Abstract: We determined the influence of adaptive optics correction on through-focus illiterate-E visual acuity and through-focus contrast sensitivity under monochromatic conditions. In two subjects, adaptive optics improved high and low (12%) contrast in-focus visual acuity by 0.1 to 0.15logMAR, but resulted in more rapid and more symmetrical deterioration in visual acuity away from in-focus. In one subject, adaptive optics improved in-focus contrast sensitivity and resulted in more symmetrical and greater loss of contrast sensitivity about the peak sensitivity because of correction of higher-order aberrations. The results show that full correction of higher-order aberrations may worsen spatial visual performance in the presence of some defocus.

The use of autorefractors using the image‐size principle in determining on‐axis and off‐axis refraction. Part 3: Theoretical effect of pupil misalignment on peripheral refraction for the Grand‐Seiko Autorefractor

Publisher: Wiley

Date: 18-02-2022

DOI: 10.1111/OPO.12964

Abstract: To determine, through simulations, the effect of lateral misalignment of the Grand‐Seiko WR‐5100K autorefractor on peripheral refraction. Using a Navarro schematic eye, into‐ and out‐of‐the eye raytracing was done for a Grand‐Seiko autorefractor simulation. For comparison, conventional out‐of‐the eye raytracing simulated the use of a Hartman‐Shack aberrometer. Peripheral refractions were determined out to ±40° along the horizontal visual field with lateral misalignments up to ±1 mm. The effects are high, and greater when misalignment and the visual field are in opposite directions than when they are in the same direction. For ex le, 1 mm nasal misalignment causes mean sphere errors of −2.7 D and +1.3 D at 30° temporal field and 30° nasal field, respectively. These effects are approximately twice those occurring in a previous experimental study. Effects are small with the Hartmann‐Shack simulation, with mean sphere errors not exceeding 0.03 D with 1 mm instrument misalignment. Misalignment of the Grand‐Seiko WR‐5100K autorefractor is predicted to cause considerable errors in peripheral refraction. The simulation produces about twice the errors found in an experimental study, and the reason for this is unknown.

Hypermetropia or hyperopia?

Publisher: Wiley

Date: 23-12-2014

DOI: 10.1111/OPO.12168

Construction, Specification, and Mathematical Description of Aspheric Surfaces

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-1983

DOI: 10.1097/00006324-198303000-00009

Abstract: Rotationally symmetrical aspheric surfaces of spectacle lenses are constructed as either "zonal aspherics" or "continuous aspherics." Zonal aspherics consist of annular zones surrounding a central zone with each zone being nominally spherical with progressively lower surface power the farther the zone is from the surface vertex. Aspheric surfaces are often specified by the radial drop in surface power from the center to the edge of the lens (e.g., Welsh Four-drop), but for assessment purposes the surface shape must be specified more precisely. The formulas for the description of continuous aspherics can be manipulated into different forms. Mathematical descriptions are given or developed which will enable theoretical assessment of the performances of all lenses with rotationally symmetrical aspheric surfaces.

Thomas Young's contributions to geometrical optics

Publisher: Informa UK Limited

Date: 07-2011

DOI: 10.1111/J.1444-0938.2010.00560.X

Abstract: In addition to his work on physical optics, Thomas Young (1773-1829) made several contributions to geometrical optics, most of which received little recognition in his time or since. We describe and assess some of these contributions: Young's construction (the basis for much of his geometric work), paraxial refraction equations, oblique astigmatism and field curvature, and gradient-index optics.

Visual backward masking performance in young adult emmetropes and myopes

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 2012

DOI: 10.1097/OPX.0B013E31823733E6

When Red Lights Look Yellow

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 11-2005

DOI: 10.1167/IOVS.04-1513

Abstract: Red signals are typically used to signify danger. This study was conducted to investigate a situation identified by train drivers in which red signals appear yellow when viewed at long distances (approximately 900 m) through progressive-addition lenses. A laboratory study was conducted to investigate the effects of defocus, target size, ambient illumination, and surround characteristics on the extent of the color misperception of train signals by nine visually normal participants. The data from the laboratory study were validated in a field study by measuring the amounts of defocus and the distances at which the misperception of the color of train signals was apparent and whether these distances varied as a function of time of day. The laboratory study demonstrated that small red targets (approximately 1 min arc) can appear yellow when viewed through small amounts of defocus (approximately +0.75 D) under bright illumination (1910 cd/m(2)). In the field study, the defocus needed to produce the color misperception was similar to that found in the laboratory study. Time of day affected the color misperception, and there was no misperception at night. The color misperception is not solely associated with progressive-addition lenses, but occurs in the presence of small amounts of positive defocus. The potential for the misperception to result in collisions and fatalities presents a major safety concern.

Lau fringes and subjective refraction

Publisher: Optica Publishing Group

Date: 04-2002

DOI: 10.1364/OL.27.000476

Abstract: Lau fringes formed in the far field of a pair of gratings illuminated by spatially incoherent light are known to disappear when one grating is rotated slightly (+/-3 degrees ) with respect to the other. We observed that a cylindrical lens that was appropriately rotated could restore the high-contrast Lau fringes by bringing together the rays that are coherent with respect to each other. We have developed a new refractometer based on this phenomenon, the details of which are presented. Measurement of the cylinder power and axis of the human eye is possible with good accuracy and repeatability with this instrument.

Comparison of blur and magnification effects on stereopsis: overall and meridional, monocularly‐ and binocularly‐induced

Publisher: Wiley

Date: 10-08-2020

DOI: 10.1111/OPO.12724

Abstract: To determine whether monocularly‐ and binocularly‐induced spherical and meridional blur and aniseikonia had similar effects on stereopsis thresholds. Twelve participants with normal binocular vision viewed McGill modified random dot stereograms to determine stereoacuities in a four‐alternative forced‐choice procedure. Astigmatism was induced by placing trial lenses in front of the eyes. Twenty‐three conditions were used, consisting of zero (no lens), +1 D and +2 D spheres and cylinders at axes 180, 45 and 90 in front of the right eye, and the following binocular combinations of both lens powers: R × 180/L × 180, R × 45/L × 45, R × 90/L × 90, R sphere/L sphere, R × 180/L × 90, R × 45/L × 135, R × 90/L × 180. Aniseikonia was induced by placing magnifying lenses in front of the eyes. Twenty‐three conditions were used, consisting of zero, 6% and 12% overall magnification and both magnifications at axes 180, 45 and 90 in front of the right eye only, and the following binocular combinations using 3% and 6% lenses: R × 90/L × 90, R × 45/L × 45, R × 180/L × 180, R overall/L overall, R × 90/L × 180, R × 45/L × 135, and R × 180/L × 90. Stereopsis losses for binocular blur effects with parallel axes (non‐anisometropic) were the same as for monocular blur effects of the same axes, and these were strongly dependent on axis (spherical blur and ×90 had the greatest effects). Binocular blur effects with orthogonal axes had greater effects than with parallel axes, with the axis combination of the former having no effect (e.g. R × 90/L × 180 was similar to R × 45/L × 135). For induced aniseikonia, splitting the magnifications between the eyes improved stereopsis slightly, and the effects were not dependent on axis. Binocular blur affects stereopsis similarly to monocular meridional blur if axes in the two eyes are parallel, whereas the effect is greater if the axes are orthogonal. In meridional aniseikonia, splitting magnification between the right and left lenses produces a small improvement in stereopsis that is independent of axis direction and right/left combination.

Corneal ectasia with Stevens–Johnson syndrome

Publisher: Informa UK Limited

Date: 03-2021

DOI: 10.1080/08164622.2021.1878835

Statistical Eye Model for Normal Eyes

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 22-06-2011

DOI: 10.1167/IOVS.10-6705

Abstract: To create a binocular statistical eye model based on previously measured ocular biometric data. Thirty-nine parameters were determined for a group of 127 healthy subjects (37 male, 90 female 96.8% Caucasian) with an average age of 39.9 ± 12.2 years and spherical equivalent refraction of -0.98 ± 1.77 D. These parameters described the biometry of both eyes and the subjects' age. Missing parameters were complemented by data from a previously published study. After confirmation of the Gaussian shape of their distributions, these parameters were used to calculate their mean and covariance matrices. These matrices were then used to calculate a multivariate Gaussian distribution. From this, an amount of random biometric data could be generated, which were then randomly selected to create a realistic population of random eyes. All parameters had Gaussian distributions, with the exception of the parameters that describe total refraction (i.e., three parameters per eye). After these non-Gaussian parameters were omitted from the model, the generated data were found to be statistically indistinguishable from the original data for the remaining 33 parameters (TOST [two one-sided t tests] P 0.05). The only exception to this was the lens refractive index, for which the generated data had a significantly larger SD. A statistical eye model can describe the biometric variations found in a population and is a useful addition to the classic eye models.

Mirror symmetry of peripheral monochromatic aberrations in fellow eyes of isomyopes and anisomyopes

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 28-06-2016

DOI: 10.1167/IOVS.16-19267

Abstract: To investigate mirror symmetry of peripheral ocular aberrations in fellow eyes of iso- and anisomyopes. Peripheral aberration was measured over the central 42° × 32° visual field for a 5-mm pupil in both eyes of 19 isomyopic (spherical equivalent refraction M [right/left]: -2.5 ± 2.1 diopters [D]/-2.7 ± 2.3 D) and 10 anisomyopic (M: -4.0 ± 1.8 D/-4.3 ± 2.8 D) young adults. Isomyopes had less than 1.0 D fellow eye refraction difference and anisomyopes had between 1.0 D and 2.6 D fellow eye differences (mean difference: 1.3 ± 0.6 D). Orthogonal regression of Zernike coefficients determined right-left eye correlations in isomyopes. For anisomyopes, higher and lower myopic eye coefficients were compared. For isomyopes, the percentages of visual field locations with significant coefficient correlations between fellow eyes varied from 100% for astigmatism ( ) to 18% for tetrafoil ( ). Positive correlations were found for , , , , , and , and negative correlations were found for , , , , and coefficients, indicating that the signs are different for corresponding locations of fellow eyes for the last five of these coefficients. Slopes of correlations were not different from ± 1, except for , , and (+0.95, -0.97, and +0.52, respectively). In anisomyopes, significant but small fellow eye differences were found for only and coefficients, with significant interactions between anisometropia and field position for only two coefficients. Peripheral aberration coefficients across the visual field show mirror symmetry in isomyopes, and in a pooled data set the coefficients with negative correlations require sign changes for left eye data. Anisometropia contributes no more to peripheral aberration differences between fellow eyes than could be expected on the basis of refraction differences between people.

Investigation of Central Visual Fields in Patients with Age-Related Macular Changes

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 03-1990

DOI: 10.1097/00006324-199003000-00006

Abstract: The effect of early macular pigmentary and drusen changes on the central visual field was investigated in elderly patients with normal visual acuities. Visual field measurements were taken with the Humphrey Field Analyser using its 24-2 and 10-2 full threshold programs. No significant differences were found between two patients groups, one with and one without the macular changes. We conclude that fine pigmentary changes and hard drusen do not cause changes in visual functioning and can be accepted as normal age-related changes.

Monochromatic aberrations of human eyes in the horizontal visual field

Publisher: Optica Publishing Group

Date: 11-2002

DOI: 10.1364/JOSAA.19.002180

Abstract: We measured the monochromatic aberrations of five subjects' right eyes both temporally and nasally out to 40 degrees from fixation. We used a Hartmann-Shack sensor with modifications to equipment and software to enable off-axis measurements. Results were standardized for 6-mm pupils. There was considerable variation among subjects in the pattern of aberrations. Aberrations were generally greater in the nasal visual field than in the temporal visual field in the case of third-order aberrations, this was true for all subjects. The contribution of third-order Zernike aberrations to the root-mean-square aberration increased up to four times from the center to the edge of the field, but the contribution of fourth- to sixth-order Zernike aberrations varied little across the visual field. Results were similar to those of a previous investigation using laser ray tracing and were of the order of those predicted by Navarro's finite schematic eye.

The value of training accommodative facility for ball sports

Publisher: Informa UK Limited

Date: 07-1997

DOI: 10.1111/J.1444-0938.1997.TB04867.X

Decoding Legal (Un)certainty in Doki Doki Literature Club!

Publisher: Routledge

Date: 29-08-2023

DOI: 10.4324/9781003197805-7

Scatter and Its Implications for the Measurement of Optical Image Quality in Human Eyes

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 2003

DOI: 10.1097/00006324-200301000-00009

Abstract: To investigate the effect of scatter on measurements of wavefront aberrations and point-spread functions in a model eye. The wavefront aberrations of a model eye were measured using Hartmann-Shack wavefront sensing and crossed-cylinder aberroscope techniques and compared with its measured point-spread function in the presence of scattering media of different concentrations. The point-spread functions became broader as the concentration increased. Forward light scatter on both the light path into the eye and the light path out of the eye contributed to this broadening of the point-spread function. Neither the crossed-cylinder aberroscope nor wavefront sensing, which, respectively, measure the ocular wavefront aberrations for light entering the eye and leaving the eye, were affected by the scatter. We predict that by minimizing the contribution of the forward light scatter from one or other of these light paths by manipulating the size of the entrance and exit pupils, it should be possible to objectively assess narrow-angle forward light scatter in the eye by measuring and removing any confounding effect from wavefront aberration.

Amplitude of accommodation in type 1 diabetes

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 08-10-2014

DOI: 10.1167/IOVS.14-15376

Abstract: People with diabetes have accelerated age-related biometric ocular changes compared with people without diabetes. We determined the effect of type 1 diabetes on litude of accommodation. There were 43 participants (33 ± 8 years) with type 1 diabetes and 32 (34 ± 8 years) age-balanced controls. There was no significant difference in mean equivalent refractive error and visual acuity between the groups. Amplitude of accommodation was measured using two techniques: objective by determining the accommodative response to a stimulus in a COAS-HD wavefront aberrometer and subjective with a Badal hand optometer. Influences of age and diabetes duration on litude of accommodation were analyzed using multiple regression analysis. People with diabetes had lower objective (2.7 ± 1.6 diopters [D]) and subjective (4.0 ± 1.7 D) litudes than controls (objective 4.1 ± 2.1 D, subjective 5.6 ± 2.1 D). Across both groups, objective litude was less than subjective litude by 1.4 ± 1.2 D. For objective litude and the whole group, the duration of diabetes contributed 57% variation to the loss of litude relative to that provided by age. For the objective litude and only the diabetes group, this was 78%. For subjective litude, the corresponding proportions were 68% and 103%. Lowered litude of accommodation exists in in iduals with type 1 diabetes when compared with age-matched controls. The loss correlated strongly with duration of diabetes. The results suggest that in iduals with diabetes will experience presbyopia earlier in life than people without diabetes, mainly due to changes in the lens.

Monocular diplopia caused by ocular aberrations and hyperopic defocus

Publisher: Elsevier BV

Date: 11-1996

DOI: 10.1016/0042-6989(96)00092-2

Abstract: As a single aperture, approximately monofocal optical system, the human eye generally creates a single image on the retina. However, the literature contains many reports of perceptual monocular diplopia. While it is easy to understand how distortion may produce monocular diplopia, its reported high incidence in normal eyes is less easily understood. We examine a model which ascribes monocular diplopia to an interaction between defocus and ocular spherical aberration. Using a psychophysical hyperacuity-based alignment procedure we measured the transverse aberration function in 0.5 mm steps horizontally across the pupil in the eyes of three cyclopleged subjects. Ocular transverse aberration functions were derived with best refraction and with simulated myopia and hyperopia. Monocular diplopia was also measured under the same conditions. All three subjects showed significant, but different, degrees of positive spherical aberration. The measured ocular transverse aberration functions were predictably modified by the hyperopic and myopic defocus. Hyperopic defocus combined with positive (myopic) spherical aberration changes a monotonic transverse aberration function with a single inflection point into a biphasic function with two inflection points. The locations of the inflections predict the presence and magnitude of the perceived diplopia. These experimental results confirm Verhoeff's (1900) hypothesis for the ocular cause of monocular diplopia.

Optical Design of Intraocular Lenses. III. On-Axis Performance in the Presence of Lens Displacement

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 10-1989

DOI: 10.1097/00006324-198910000-00003

Abstract: The effect of intraocular lens shape on on-axis performance of model pseudophakic eyes was investigated, when lenses were displaced by tilting or decentration. Image quality criteria included an optimization procedure, spot diagrams, and the modulation transfer function (MTF). Displacement adversely affects image quality. With conventional lens shapes, the deterioration is either small or retinal image quality can be nearly restored to predisplacement levels by spectacle correction. Optimum lens shapes in the presence of decentration are close to being plano-convex, with the more curved surface facing the cornea. Based on the results of this and previous studies, it is suggested that preferred shapes of intraocular lenses range from this plano-convex form to equi-convex.

Introduction

Publisher: Routledge

Date: 29-08-2023

DOI: 10.4324/9781003197805-1

Tolerance to spherical aberration induced by rigid contact lenses

Publisher: Wiley

Date: 1992

DOI: 10.1111/J.1475-1313.1992.TB00249.X

Peripheral Ocular Aberrations in Mild and Moderate Keratoconus

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Date: 12-2010

DOI: 10.1167/IOVS.10-5188

Abstract: To investigate the influence of keratoconus on peripheral ocular aberrations. Aberrations in seven mild and five moderate keratoconics were determined over a 42° horizontal × 32° vertical visual field, with a modified aberrometer. Control data were obtained from an emmetropic group. Most aberrations in the keratoconics showed field dependence, predominately along the vertical meridian. Mean spherical equivalent M, oblique astigmatism J(45), and regular astigmatism J(180) refraction components and total root mean square aberrations (excluding defocus) had high magnitudes in the inferior visual field. The rates of change of aberrations were higher in the moderate than in the mild keratoconics. Coma was the dominant peripheral higher-order aberration in both the emmetropes and the keratoconics for the latter, it had high magnitudes in the center and periphery of the visual field. Greater rates of change in aberrations across the visual field occurred in the keratoconus groups than in the emmetropic control group. The moderate keratoconics had more rapid changes in, and higher magnitudes of, aberrations across the visual field than did the mild keratoconics. The dominant higher-order aberration for the keratoconics across the visual field was vertical coma.

Effect of conicoid asphericity on the Tscherning ellipses of ophthalmic spectacle lenses

Publisher: Optica Publishing Group

Date: 04-1983

DOI: 10.1364/JOSA.73.000441

Abstract: One of the criteria in ophthalmic spectacle lens design is the elimination of oblique astigmatism. For a range of equivalent powers, Seidel (primary or third-order) astigmatism can be eliminated, and the solutions of back- (or front-) surface power are commonly displayed graphically in the form of ellipses (Tscherning ellipses). The Tscherning ellipses apply only to lenses constructed from spherical surfaces. If one or both surfaces are made aspheric, the solutions for zero astigmatism are no longer in the form of ellipses. If one surface, usually the front surface, is made as a conicoid aspheric, the solutions for zero astigmatism can be presented graphically similarly to the Tscherning ellipses. For any given equivalent power, there are two or no solutions for spherical lenses. However, there is always one and up to three solutions for conicoid aspheric lenses.

Recent advances in measurement of monochromatic aberrations of human eyes

Publisher: Informa UK Limited

Date: 2005

DOI: 10.1111/J.1444-0938.2005.TB06659.X

Abstract: The field of aberrations of the human eye is moving rapidly, being driven by the desire to monitor and optimise vision following refractive surgery. It is important for ophthalmologists and optometrists to have an understanding of the magnitude of various aberrations and how these are likely to be affected by refractive surgery and other corrections. In this paper, I consider methods used to measure aberrations, the magnitude of aberrations in general populations and how these are affected by various factors (for ex le, age, refractive error, accommodation and refractive surgery) and how aberrations and their correction affect spatial visual performance.

Third-order theory of spectacle lenses applied to correction of peripheral refractive errors

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 02-2011

DOI: 10.1097/OPX.0B013E31820847D2

Effect of cataract-induced refractive change on intraocular lens power formula predictions

Publisher: Optica Publishing Group

Date: 02-04-2021

DOI: 10.1364/BOE.422190

Abstract: Cataract-induced refractive change ( CIRC ) is the change in refraction induced by a cataract. It can amount to several diopters (D). It alters predicted errors in refraction following cataract surgery through changes in axial length measurement. This study determined the effect of CIRC on the accuracy of intraocular lens power formula predictions of refraction in 872 eyes of 662 patients. Regression of results gave −0.030 D prediction error per 1 D of CIRC , i.e. cataract-induced myopia and hyperopia tended to yield postoperative hyperopia and myopia, respectively. Theoretical determinations with a model eye supported this result. There was significant correlation of nuclear cataract opalescence with CIRC . Although these effects are difficult to identify based on changes in refraction, if biometers were able to identify cataract density and automatically adjust axial length measurement, IOL power predictions might improve.

The influence of oblique viewing on axial and peripheral refraction for emmetropes and myopes

Publisher: Wiley

Date: 10-02-2009

DOI: 10.1111/J.1475-1313.2008.00623.X

Abstract: Refraction may be affected by the forces of lids and extraocular muscles when eye direction and head direction are not aligned (oblique viewing) which might potentially influence past findings on peripheral refraction of the eye. We investigated the effect of oblique viewing on axial and peripheral refraction. In a first experiment, cycloplegic axial refractions were determined when subjects' heads were positioned to look straight-ahead through an open-view autorefractor and when the heads were rotated to the right or left by 30 degrees with compensatory eye rotation (oblique viewing). Subjects were 16 young emmetropes (18-35 years), 22 young myopes (19-36 years) and 15 old emmetropes (45-60 years). In a second experiment, cycloplegic peripheral refraction measurements were taken out to +/-34 degrees horizontally from fixation while the subjects rotated their heads to match the peripheral refraction angles (eye in primary position with respect to the head) or the eyes were rotated with respect to the head (oblique viewing). Subjects were 10 emmetropes and 10 myopes. We did not find any significant changes in axial or peripheral refraction upon oblique viewing for any of the subject groups. In general for the range of horizontal angles used, it is not critical whether or not the eye is rotated with respect to the head during axial or peripheral refraction.

Determining specified intraocular lens powers when silicone oil is to be used in the vitreous chamber

Publisher: Ovid Technologies (Wolters Kluwer Health)

Date: 08-2023

DOI: 10.1097/J.JCRS.0000000000001190

Abstract: To apply a theoretical approach to determining how specified intraocular lens (IOL) powers should change when vitreous oil substitution is combined with IOL implantation. University laboratory, private Ophthalmological practice. Theoretical raytracing. Raytracing was done backwards from the retina with equi-convex 20 diopters (D) and 25 D IOLs, of refractive index 1.5332, to the object side of the anterior IOL surface. The 1.336 vitreous index was replaced with a high index 1.405 silicone oil. Raytracing was repeated with increase in specified power, that power as if 1.336 index was still surrounding the IOL, so that the object reduced vergence on the anterior side of the lens matched that of the original IOL power. This was done for a range of lens shapes from plano-convex (front surface flat), through equi-convex, to plano-convex (back surface flat), and for a range of axial lengths. The true power, the power with 1.336 index on the object side and silicone oil on the image side, was also determined. Replacing vitreous by silicone oil increases the necessary specified IOL power. This increase varies from approximately 14% for flat back surfaces, to 40% for equi-convex lenses, to 80% for flat front surface IOLs. True powers increase by about 15% across the range of IOL shapes. In terms of percentages, effects of changing the original IOL power and the axial length are small. When silicone oil is to remain in an eye after cataract surgery, biconvex IOLs require much higher specified powers than convex-plano IOLs.

Off‐axis measurements of a plano distance power progressive addition lens

Publisher: Wiley

Date: 07-1993

DOI: 10.1111/J.1475-1313.1993.TB00482.X

Abstract: To test that the Humphrey Lens Analyzer can be used validly to measure off-axis powers of progressive addition lenses of low distance power, we made measurements of a plano distance progressive power lens with both a conventional focimeter and the Humphrey Lens Analyzer. The use of the Humphrey Lens Analyzer in two modes, one in which the lens rotated about a point corresponding to the centre-of-rotation of the eye (mode 1) and one in which the lens rotated about its back surface centre of curvature (mode 2), gave off-axis power measurements which were similar to those of conventional measurements. In addition, the Humphrey Lens Analyzer in mode 1 gave prism measurements which were similar to conventional measurements. The Humphrey Lens Analyzer in mode 2 gave prism measurements which were less than those of conventional measurements, but the prism contours were similar and the differences were < 1 delta within 20 mm of the lens centre.

University Of The Sunshine Coast

Location: Australia

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Griffith University

Location: Australia

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Queensland University Of Technology Faculty Of Health

Location: Australia

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Linkage Projects - Grant ID: LP100100575

Start Date: 07-2010

End Date: 12-2013

Amount: $240,546.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0558209

Start Date: 02-2005

End Date: 12-2007

Amount: $214,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354517

Start Date: 12-2003

End Date: 12-2004

Amount: $20,000.00

Funder: Australian Research Council

Linkage - International - Grant ID: LX0881907

Start Date: 2008

End Date: 12-2008

Amount: $16,508.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP110102018

Start Date: 2011

End Date: 12-2014

Amount: $333,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP190103069

Start Date: 03-2019

End Date: 12-2023

Amount: $425,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140101480

Start Date: 06-2014

End Date: 12-2017

Amount: $390,000.00

Funder: Australian Research Council