ORCID Profile
0000-0002-2393-0644
Current Organisation
Deakin University
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Publisher: Informa UK Limited
Date: 1983
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 23-03-2009
DOI: 10.1212/01.WNL.0000345040.01917.9D
Abstract: The autosomal recessive disorder Niemannn-Pick type C (NPC) presents in adulthood with psychosis or cognitive deficits associated with supranuclear gaze palsies. While saccadic innervation to the extraocular muscles is generated in the brainstem, the frontal lobes play an integral role in the initiation of volitional saccades and the suppression of unwanted reflexive saccades. No study has examined the frontally driven volitional control of saccadic eye movements in NPC. To examine self-paced and antisaccades as well as reflexive saccades in adult patients with NPC, a disorder known to affect brainstem and frontal cortical function. Three biochemically confirmed adult patients with NPC were compared with 10 matched controls on horizontal saccadic and antisaccadic measures using an infrared limbus eye tracker. Patients' cholesterol esterification and filipin staining, Mini-Mental State performance, and NPC symptom level were rated. Reflexive saccade latency ranged from shorter to longer than normal, reflexive saccade gain was reduced, asymptotic peak velocity was reduced, fewer self-paced saccades were generated, and increased errors on antisaccades were made by patients compared to controls. Patients with more severe biochemical, cognitive, and symptom deficits performed most poorly on brainstem and frontal ocular motor measures. Paradoxically, less severe illness was associated with an abnormally reduced saccadic latency. Ocular motor measures provide an index of disease severity in Niemannn-Pick type C (NPC) and may be a useful adjunct for monitoring the illness progress and medication response. Reduced saccadic latency may result from inadequate fixation input from abnormally functioning frontal eye fields in NPC.
Publisher: Elsevier BV
Date: 05-1980
DOI: 10.1016/0014-4886(80)90091-6
Abstract: This study aims to determine the frequency and prognostic significance of lactic acidosis in children with diabetic ketoacidosis (DKA) admitted to the pediatric intensive care unit. The study was carried out retrospectively by examining the patients admitted to the pediatric intensive care unit for the treatment of DKA. The ages of the patients ranged from 2 to 18 years. The patients with the following parameters were enrolled in the study: serum blood glucose>200 mg/dL, ketonuria presence, venous blood gas pH ≤7.1, bicarbonate <15. A total of 56 patients were included in the study with a mean age of 111.07 ± 51.13 months. The recovery time from DKA was 16.05 ± 6.25 h in the group with low lactate level and it was 13.57 ± 8.34 h in the group with high lactate level with no statistically significant difference. There was a negative correlation between lactate levels and the recovery time from DKA. Lactic acidosis is common in DKA, and unlike other conditions, such as sepsis, it is not always a finding of poor prognosis that predicts the severity of the disease or mortality. We think that high lactate may even protect against possible brain edema-cerebral damage in DKA.
Publisher: Elsevier BV
Date: 10-1994
DOI: 10.1016/0006-3223(94)90616-5
Abstract: Although the range of normal ocular motor performance is broad, little is known about the sources of variability. Genetic transmission of eye movement deficits has been described but such possible control of normal function has been little investigated. Characteristics of smooth pursuit and saccades can be examined for the degree of concordance in related in iduals. In this pilot study, we studied saccades and pursuit in eight monozygotic (MZ) twin pairs. The statistical analysis of the data used the intraclass correlation of MZ twins (rMZ) to estimate what fraction the covariance of the twin pairs was of the population variance. All saccadic measures showed significant MZ correlations (p < 0.05). Smooth pursuit gains were even more highly correlated (p < 0.001). These results indicate considerable similarity within pairs of twins, particularly for horizontal smooth pursuit, and suggest that larger studies on monozygotic and dizygotic twins would be desirable, to help separate out the relative contributions of environmental and genetic factors.
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 19-03-2013
Abstract: We examined factors influencing perceptual stability in observers with fusion maldevelopment nystagmus syndrome (FMNS). In addition, we also investigated the effect of visual demand, task-related physiologic stress, and motivation on the nystagmus waveform. Perception of oscillopsia during daily activities was assessed via a questionnaire. Perception of oscillopsia in the laboratory was assessed using central and peripheral (10°) light emitting diodes (LEDs) in front of a background display of random, fixed-contrast shapes. Task-induced stress was achieved via a time restricted acuity task with or without concurrent mental arithmetic challenge, and motivation varied using a reward-penalty paradigm. The experiments have been previously described elsewhere. Six out of nine subjects reported experiencing oscillopsia in certain daily activities. in the laboratory, the percentages of trials with perceptions of motion of the led and background were as follows: neither, 60% to 70% background only, 20% to 30% both, 5% to 15%, and LED only, 5% to 15%. Over all trials, six of nine experienced oscillopsia for both the low- and high-contrast image respectively (i.e., three subjects never experienced oscillopsia). The background was frequently seen moving for both images regardless of contrast and/or condition. Trials with and without oscillopsia did not differ when comparing foveation. In the second experiment, task-related physiologic stress and motivation were reflected in an increase in heart rate nystagmus waveform intensity increased and foveation decreased. The magnitude of changes in heart rate was uncorrelated with changes in waveform parameters for all experiments, however. Preliminary results suggest that the FMNS group does perceive spatially inhomogeneous oscillopsia, similar to infantile nystagmus syndrome (INS), in certain visual environments. In investigating the effect of stress and motivation on FMNS, a new, if tentative, finding suggests that task-induced stress and/or motivation may have a negative impact on the nystagmus. Taken together, our findings provide an insight into the particular environments and tasks that are likely to present particular challenges to persons with FMNS.
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 21-01-2011
DOI: 10.1167/IOVS.10-6016
Abstract: To use the suppression of optokinetic nystagmus (OKN) as an objective measure of subjects' ability to distribute their visual attention to different elements-static or dynamic, simple or complex-in their visual environment. Large-field, constant-velocity projected images, along with a stationary central fixation target were presented to 25 young participants (13 women). Images were either black O's with a few X's or red C's, blue T's, and a few red T's, with the X's and red T's as the search targets. Stationary targets at either 0° or ±12.5° were either blinking squares or a rapid succession of colored shapes-blinks or green stars were the target events. Central fixation was maintained at all times. OKN gain was calculated for all tasks and analyzed in a mixed 4-way ANOVA, with the sex of the subjects as the group variable and dynamism, location, and complexity as within-subject effects. There was no effect of sex all three main within-subject effects were significant, as were the two-way interactions between them and an interaction between dynamism and sex. The most striking result was that there was little difference across static tasks but that dynamic tasks showed significantly more OKN breakthrough, particularly for the complex search presented centrally. In this group of normal-sighted young subjects, OKN breakthrough was sensitive to a range of stimulus characteristics. This finding allows a single outcome measure to be used across a wide range of possible tasks and may be useful in assessing the effects of age and disease.
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.BRAINRES.2008.07.054
Abstract: Previous studies have suggested that baseline and task-related activity within the prefrontal cortex varies with the degree of extraversion we examined whether this trait influenced performance on the antisaccade task, a measure commonly used in psychiatric and neurological disorders. Extraversion was assessed in young normal subjects using the Eysenck Personality Questionnaire-Revised Short-scale. Highly extraverted and highly introverted subjects' antisaccade errors and latencies were evaluated. Extraversion was associated with significantly more errors but did not influence the latency of either correct or erroneous responses. This effect on error rate but not latency is similar to that seen in schizotypal personality disorder, whereas normal ageing, as well as schizophrenia and attention deficit-hyperactivity disorder, increase errors and also delay saccade onset. This is the first study in a young, non-clinical population to show an influence of a normal personality dimension on an ocular motor measure.
Publisher: Informa UK Limited
Date: 03-2006
DOI: 10.1111/J.1444-0938.2006.00024.X
Abstract: This review examines current approaches to the diagnosis and management of congenital forms of nystagmus. Emphasis is placed on diagnostic features that are amenable to clinical identification but those issues that can be addressed only with more detailed investigations, such as eye movement recording, are indicated. Non-surgical management, including prism spectacles, contact lenses and vision therapy, is discussed, as are surgical approaches. Because many aspects of congenital forms of nystagmus, particularly as experienced by patients with the condition in their normal lives, are poorly addressed in both the clinical and research literature, these limitations are also highlighted.
Publisher: Elsevier BV
Date: 04-2007
DOI: 10.1016/J.NEUROBIOLAGING.2006.02.003
Abstract: Most studies on the effects of ageing on saccades have examined reflexive saccades the only commonly studied volitional task has been the antisaccade task, with contradictory results. We examined in both young and elderly normal subjects the latency of anti-, memory-guided, and predictable saccades and the timing of self-paced saccades we also evaluated errors made on the first two tasks. We expected errors to be correlated between tasks we also expected antisaccade latencies and errors to be inversely correlated. We also expected antisaccade and memory-guided saccade latencies to be longer in in iduals with a high self-paced rate. Except for predictable saccades, mean latencies were significantly higher in the elderly. However, their performance was more variable. Errors were also significantly more frequent on anti- and memory-guided saccade tasks. Most of the hypothesised correlations were not observed. Analysis of error latencies showed that whilst most antisaccade errors were reflexive, for memory-guided saccades both express errors and errors with latencies between 0.4 and 2.5 s were observed. The latter appeared to be a premature release of what would otherwise have been a properly planned response. Age thus impaired all but the predictable saccade task nevertheless, there were few relationships between measures across tasks. This suggests that a range of processes mediate peoples' performance on these saccade paradigms.
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.EXER.2018.08.011
Abstract: The utility of optokinetic nystagmus suppression as an index of visual attention has been demonstrated however, a gap exists in our understanding of the effects of aging on attentional ision. The purpose of this study was to explore the effect of a subject's age upon their ability to allocate visual attention among multiple salient elements which varied in location and complexity. Large-field optokinetic nystagmus (OKN)-inducing animations were presented along with a central flashing fixation point to 27 subjects: 15 younger adults (range 19-23, mean age 21.4) and 12 older adults (range 65-89, mean age 74). Subjects were instructed to fixate on a central point while attending to either moving features of the background or solely to the fixation target. Failure of subjects to accurately ide their attention was quantified by optokinetic gain (eye velocity/background velocity). Gain was analysed in two separate 3-way ANOVAs: one at the central location with the between-subjects variable of age and within-subjects variables of complexity and dynamism and one using only the dynamic tasks, including a between-subjects variable of age and within-subjects variables of complexity and location. A strong effect of age was found between subjects during the more attentionally demanding dynamic tasks, but there was only a marginal effect during the static tasks. All within-subjects variables were highly significant, and there were several significant 2- and 3-way interactions. This study provides strong evidence for the compounding effects of senescence and stimulus characteristics on an adult's ability to accurately allocate visual attention. These findings show that OKN suppression may be a useful framework for quantification of attentional resources in older subjects.
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.JOCN.2005.10.010
Abstract: Attentional resources are finite and decline with age. We measured subjects' abilities to generate optokinetic nystagmus (OKN), to suppress it with fixation and to continue to suppress it when fixating while simultaneously paying covert attention to a feature of the optokinetic (OK) stimulus. During fixation with a red laser spot, OKN was almost fully suppressed. When subjects suppressed the OKN while simultaneously paying covert attention to a feature of the OK stimulus, suppression of the OKN was less well suppressed. The active OKN was vigorous. Age affected only the ided attention task, perhaps reflecting a diminution in resources of attention with age. The neural pathways serving attention and those serving eye movements appear to be closely related. We suggest the test presented here represents an objective measurement of the ability to ide attention, and that it has the potential to be developed for much more widespread, possibly clinical, use.
Publisher: Springer Science and Business Media LLC
Date: 02-2004
DOI: 10.1007/S00221-003-1749-1
Abstract: To examine the accuracy and latency of reflexive saccades to vibratory stimulation of the fingertips made by normal human subjects and to compare the findings to those of visually guided saccades. Eye movements were recorded using infrared oculography. Stimuli were presented via an array of audiometric bone vibrator transducers driven at 250 Hz and positioned at eye level in a darkened room. Target locations were at 0 and +/-5, 10, and 15 deg. Visual stimuli were green LEDs. Saccades were analysed interactively off-line and latency and litude measured for both types of saccade. Saccades to tactile stimuli had longer latencies and showed less accurate final eye positions than those to equivalent visual targets they were unaffected by subject age. Error magnitude for the tactile saccades increased monotonically with increasing target eccentricity because the fingers remained in a fixed position throughout the testing, this also meant that error was lowest for the thumb and increased with progression outwards towards the ring finger. Visually guided refixations were accurate and differed less than 0.2 deg across target locations. Subject age had no effect on performance. Human subjects may make relatively accurate refixations to tactile targets in the absence of visual cues, but only to certain locations/fingers others were localised very poorly. Further studies are needed to determine whether finger selection or target location is the primary determinant of accuracy in this task.
Publisher: Elsevier BV
Date: 04-2005
DOI: 10.1016/J.VISRES.2004.11.004
Abstract: Commonly, when an in idual with congenital nystagmus (CN) performs a visually demanding task their nystagmus intensifies and their visual acuity decreases, probably due to poorer foveation. However, the relationship between fixation attempt and nystagmus waveform has never been quantified. In this study 14 CN subjects viewed a Landolt C of varying orientation and size. They indicated its orientation via a button array whilst eye movements were recorded. Foveation was uncorrelated with optotype size. These results suggest that CN is not exacerbated by visual demand per se rather the need to do something visually demanding of importance to the in idual.
Publisher: Informa UK Limited
Date: 1985
DOI: 10.3109/00016488509108591
Abstract: The gain of the vestibulo-ocular reflex (slow-phase eye velocity/chair velocity, measured in the dark) was compared in 11 normal healthy subjects who habitually wore corrective spectacles of varying strength. The rotational magnification (or prismatic effect) induced by habitually wearing corrective spectacles caused the VOR gain measured in darkness to vary systematically with diopter of correction. Even when allowances were made for the inherent variability of measurement of the VOR gain, myopes tended to have lower gains and hyperopes higher gains. This study demonstrates that the clinician should account for spectacle adaptation to properly interpret the results of vestibular function tests.
Publisher: Informa UK Limited
Date: 1986
DOI: 10.3109/00016488609108647
Abstract: Smooth pursuit eye movements made in response to 5 and 20% targets were studied in young and old subjects. Tracking of a target was carried out both with no competing stimuli and while auditory and visual distractions were presented. Only tracking the target against a projected background significantly impaired pursuit. It did so in both age groups, by reducing pursuit gain and also by eliciting 'anticipatory saccades', which took the eyes ahead of the target to a new fixation point for 0.5 s or longer. Elderly subjects showed a significantly greater number of such interruptions, however, suggesting that continuous performance of the tracking task could be more readily disrupted in this group. These findings may arise from changes in the way in which elderly in iduals process incoming sensory information.
Publisher: Elsevier BV
Date: 1983
DOI: 10.1016/0042-6989(83)90038-X
Abstract: Age effects on human saccadic eye movements were tested with infrared reflectance oculography in 34 subjects. In contrast to a prior report, only a slight non-significant change was observed in saccadic velocity and duration. An increase in saccadic latency comparable to that found in several previous reports was observed, however. All parameters showed considerable intersubject variability for both age groups. Decreased velocities or increased durations outside of these normal, broad ranges should be regarded as pathological for all subjects they are not physiological effects of the aging process.
Publisher: Elsevier BV
Date: 06-1992
DOI: 10.1016/0042-6989(92)90002-Z
Abstract: Smooth pursuit abnormalities have been reported in patients with schizophrenia and their first-degree relatives, suggesting that abnormal tracking may serve as a biological marker for schizophrenia. Recent studies in schizophrenic patients have found reduced pursuit gain, low initial acceleration and abnormal gain-corrective saccade interactions. Impaired saccadic initiation has been noted in anti-saccade tasks and in predictive saccade generation, as has saccadic hypometria. While abnormalities have been found in affective disorder patients, studies of their first-degree relatives suggest that abnormalities during pursuit are more closely associated with schizophrenia. Identification of specific defects allows informed speculation about their neural substrates and suggests possible relationships between the ocular motor defects and other cognitive and perceptual abnormalities associated with the major psychiatric disorders.
Publisher: American Society of Neuroradiology (ASNR)
Date: 13-12-2013
DOI: 10.3174/AJNR.A3356
Publisher: S. Karger AG
Date: 2002
DOI: 10.1159/000057702
Abstract: i Objectives: /i Studies of saccadic eye movement impairment in Alzheimer’s disease (AD) have largely focused on simple reflexive eye movements and the antisaccade task. The effects of manipulating stimulus timing have been little studied. i Methods: /i Fourteen patients with mild to severe AD and 11 age-matched controls were studied on the antisaccade task, while latencies on simultaneous, gap and predictable tasks were recorded from 11 patients and 11 controls. Dementia severity was assessed with the Mini-Mental State Examination. i Results: /i As a group, patients’ latencies were significantly higher and more variable on the simultaneous and gap tasks. Predictable task performance was similar in mean but significantly more variable. Grossly anticipatory responses by patients were common on the predictable, simultaneous and gap tasks. Exclusion of these from subject means revealed that AD patients, when making target-driven saccades, demonstrated a gap effect of similar magnitude to normal subjects. Patients made significantly fewer correct antisaccades and significantly more reflexive errors not followed by a corrective antisaccade than did controls. i Conclusions: /i The frequent presence of grossly anticipatory saccades may reflect dysfunction of fixation mechanisms possibly involving projections from frontal lobe to superior colliculus. The less frequently seen, marked prolongation of latency may reflect changes in posterior parietal mechanisms mediating reflexive saccade generation. The presence of the gap effect demonstrates a continued ability to benefit from externally controlled stimulus disengagement. Patients’ ability to make appropriately timed saccades to targets of known locations was particularly impaired, but the target sequence itself was at least grossly correctly learned. Larger studies may be able to identify clinically distinct populations of AD patients.
Publisher: Informa UK Limited
Date: 17-10-2023
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF00873543
Publisher: Elsevier BV
Date: 05-1980
DOI: 10.1016/0014-4886(80)90093-X
Abstract: Thyroid disorders are common in diabetics and related to severe diabetic complications. TRPV2 ion channels have crucial functions in insulin secretion and glucose metabolism which have an important role in the pathophysiology of diabetes. Also, they have a significant effect on various immunological events that are involved in the HT pathophysiology. This study aimed to investigate rs14039 and rs4792742 polymorphisms of the TRPV2 ion channels in type 2 diabetes mellitus (T2DM, n=100) Hashimoto thyroiditis (HT, n=70) and comorbid T2DM and HT (T2DM+HT, n=100) patients and control (n=100). Case-control study. RT-PCR genotyping was used to determine rs14039 and rs4792742 polymorphisms with DNA s les of subjects and appropriate primer and probes. Besides, required biochemical analyses were performed. It was determined that the frequencies of the rs14039 GG homozygote polymorphic genotype and the G allele were significantly higher in T2DM+HT patients compared to the control (p=0.03 and p=0.01, respectively) and that especially the GG genotype increases the risk of T2DM+HT 3.046-fold (p=0.01, OR=3.046). It was detected that the GG genotype increased the risk of HT 2.54-fold (p=0.05, OR=2.541). TRPV2 rs4792742 polymorphisms reduce the risk of HT and T2DM+HT comorbidity almost by half and have a protective effect against HT and T2DM+HT. The rs14039 GG genotype of the TRPV2 gene significantly increases the risks of development of T2DM+HT and HT disorders, may have a significant role in the pathophysiology of these diseases, also leading to predisposition for their development. Conversely, rs4792742 polymorphic genotypes have a strong protective effect against the HT and T2DM+HT comorbidity.
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.YMGME.2012.11.009
Abstract: Cerebellar Purkinje cells are known to be highly vulnerable to neuronal pathology in Niemann-Pick type C (NPC), a disease where widespread white matter changes have also been reported. We sought to determine the relationship between white and grey matter cerebellar changes and clinical variables in NPC. Ten adult patients with NPC were matched to control subjects (n=27) on age and gender. Patients were rated for symptom duration and severity, degree of ataxia, and were assessed for saccadic eye measures. Cerebellar white and grey matter volumes were automatically segmented using the Freesurfer software package. NPC patients had a significant reduction in both grey and white matter volumes. Volume did not correlate with symptom duration or severity, but did correlate with saccadic gain and ataxia measures. Both cerebellar grey and white matter volume decreases in adult NPC, and these changes are associated with impairments in saccadic gain and in motor control.
Publisher: Elsevier BV
Date: 11-2003
DOI: 10.1016/S0042-6989(03)00462-0
Abstract: Although the absence of oscillopsia is a common feature of congenital nystagmus (CN), it is occasionally noted by patients under poor viewing conditions and has been provoked in laboratory settings with stabilised images. In the present study, the effects of reductions in background stimulus size and luminance on perceptual stability in CN were examined. Sixteen CN subjects were first interviewed using a structured questionnaire about whether they ever experienced oscillopsia and, if so, under what circumstances and with what perceptions. They next fixated an LED centred in projected images of three sizes (21x14 degrees, 10x6 degrees and 7x4 degrees) and four luminance levels (115.5, 24.5, 2.7 and 0.1 cd/m2, with contrasts from 96 down to 20%). Eye movements were recorded with a limbal tracker. They were asked after viewing each image "whether anything happened to the image while they watched it." Occasional oscillopsia was reported by 12/16 of the CN subjects on the questionnaire. In the laboratory, 13/16 subjects experienced oscillopsia in some manner for at least one of the stimuli. 8/13 CN subjects experienced it for the dimmest and smallest slides. 11/13 perceived certain parts (either the LED or background) of the visual stimuli as moving, with the perception of LED movement most pronounced at low background luminance. Foveation did not differ when trials with and without reported oscillopsia were compared (independent s les t-test, p>0.05). Oscillopsia may occur in CN with normal viewing of bright fixation targets against dim backgrounds. Under these conditions, the oscillopsia may be spatially inhomogeneous. Luminance differences between the fixation point and surround may have caused transmission time differences as the image moved across the retina, therefore leading to the perception of motion in one portion of the scene and not the other.
Publisher: Wiley
Date: 19-12-2014
DOI: 10.1111/DMCN.12345
Abstract: The aim of this study was to determine whether volitional saccadic impairments are present in children with mild closed head injury (mCHI) and whether these deficits are predictive of ongoing cognitive impairment. We analysed a s le of 26 children with mCHI (20 males, 6 females mean age 13y 1mo, SD 2y) and 29 age-matched comparison children (20 males, 9 females mean age 12y 2mo, SD 2y). Participants completed a battery of saccadic eye movement tasks and a set of computer-based cognitive tasks at three time points: within 2 weeks of mCHI, and at 3 months and 6 months. The group with mCHI made fewer errors on the antisaccade task at the first time point and showed increased latencies on prosaccades, correct antisaccades, and corrected antisaccade errors at the third time point (6mo). The group with mCHI also showed poorer performance on the cognitive tasks assessing memory. Even very mild, uncomplicated mCHI in children may persistently affect aspects of executive control and visual processing.
Publisher: Elsevier BV
Date: 1978
Publisher: Informa UK Limited
Date: 1988
Publisher: Informa UK Limited
Date: 1992
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 07-2008
DOI: 10.1167/IOVS.07-1626
Abstract: To investigate the effect of visual demand, task-related physiological stress, and motivation on the nystagmus waveform of 19 subjects with infantile nystagmus syndrome (INS). Subjects viewed a Landolt C of varying orientation and size, and indicated its orientation via arrow keys on a keyboard. Mental arithmetic was performed in conjunction with the visual task. Subjects then underwent a reward-penalty paradigm. Eye movements and heart rates were recorded during all experiments. Task-related physiological stress and motivation were reflected in an increase in heart rate and led to an increase in the litude, frequency, and intensity of the nystagmus waveform and a decrease in foveation-period durations. Changes in heart rate did not correlate with changes in waveform parameters for all experiments. The results show, for the first time, the negative impact of task-induced stress and/or motivation on the characteristics of INS. This finding has important implications for in iduals with INS, because stress may arise in everyday situations, such as driving or when undertaking an examination.
Publisher: Informa UK Limited
Date: 1988
Publisher: Elsevier BV
Date: 02-01-1999
DOI: 10.1016/S0021-5155(98)00060-4
Abstract: Voluntary nystagmus has been recognized as a pendular, rapid, conjugate, primarily horizontal, benign eye movement initiated and maintained by voluntary effort. A 10-year-old Japanese girl presented with voluntary nystagmus associated with accommodation spasms. Her chief complaints, intermittent blurred vision, headache, and soreness of the eyes, were thought to be related to the voluntary nystagmus and accommodation spasms. The waveform of the nystagmus appeared pendular, the frequency was 13-15 Hz, and the litude was 3-5 degrees. Scanning laser ophthalmoscopic video images clearly demonstrated vertical and torsional components in addition to the horizontal eye movements. Her refraction was unstable, varying between -0.5 diopters (D) and -5.5 D, and the recording of the accommodometer increased to -12.0 D when nystagmus was initiated. This may be a unique form of voluntary nystagmus that consists of horizontal, vertical, and rotational components associated with accommodation spasms. Observation of this patient continues, without any further treatment or examination.
Publisher: Cold Spring Harbor Laboratory
Date: 18-01-2022
DOI: 10.1101/2022.01.18.476817
Abstract: Cognitive processes can influence the characteristics of saccadic eye movements. Reading habits, including habitual reading direction, also affects cognitive and visuospatial processes, favouring attention to the side where reading begins. Few studies have investigated the effect of habitual reading direction on saccade directionality of low-cognitive-demand stimuli (such as dots). The current study examined horizontal prosaccade, antisaccade and self-paced saccade in subjects with two primary habitual reading directions. We hypothesised that saccades responding to the target in subject’s habitual reading direction would show a longer prosaccade latency and lower antisaccade error rate (errors being a reflexive glance to a sudden-appearing target, rather than a saccade away from it). Sixteen young Chinese participants with primary habitual reading direction from left to right and sixteen young Arabic and Persian participants with primary habitual reading direction from right to left were recruited. Subjects needed to look towards a 5 ° / 10 ° target in the prosaccade task or look towards the mirror image location of the target in the antisaccade task and look between two 10-degree targets in the self-paced saccade task. Only Arabic and Persian participants showed a shorter and directional prosaccade latency towards 5 ° target against their habitual reading direction. No significant effect of primary reading direction on antisaccade latency towards the correct directions was found. However, we found that Chinese readers generated significantly shorter prosaccade latencies and higher antisaccade directional errors compared with Arabic and Persian readers. The present study provides an insight into the effect of reading habits on saccadic eye movements in response to low-cognitive-demand stimuli and offers a platform for future studies to investigate the relationship between reading habits and neural mechanisms of eye movement behaviours.
Publisher: Informa UK Limited
Date: 2003
DOI: 10.1076/STRA.11.2.109.15105
Abstract: It is generally agreed that vertical prism bar training can increase vertical fusion litude. However, little is known as to whether the increased vertical fusion litude following vergence exercise is due to improvement of the sensory or the motor system or both. The main aim of the present study was to determine the effect of vertical prism bar training on the motor and sensory components of vertical fusion. Fifty normal subjects between 17 and 25 years of age were given vertical prism bar training to improve their vertical fusion litude. Vertical vergence eye movements were recorded using an infrared reflectance eye tracker system. The sensory component was assessed using a Sheedy disparometer. The findings of the present study showed that the average increase in vertical motor fusion was approximately 30% following vertical prism bar training. The maximum magnitude of VFD remained unchanged in the majority (73%) of subjects. The increase in the vertical fusion litude following vertical prism bar training is largely due to improvements in the vertical motor fusion. The prism training has little effect on the sensory component.
Publisher: Elsevier BV
Date: 05-1980
Publisher: Informa UK Limited
Date: 1984
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 02-12-2014
Abstract: The factors contributing to the cause and maintenance of anorexia nervosa (AN) are poorly understood, though increasing interest surrounds the neurobiological underpinnings of the condition. The examination of saccadic eye movements has proven useful in our understanding of the neurobiology of some other psychiatric illnesses, as they utilize identifiable brain circuits. Square wave jerks (SWJs), which describe an involuntary saccade away and back to fixation, have been observed to occur at abnormally high rates in neurodegenerative disorders and some psychiatric illnesses, but have not been examined in AN. Therefore, the aim of this study was to investigate whether in iduals with AN and healthy control (HC) in iduals differ in SWJ rate during attempted fixation. Square wave jerk frequency was compared across 23 female participants with AN and 22 HC participants matched for age, sex, and premorbid intelligence. Anorexia nervosa participants were found to make SWJs at a significantly higher rate than HC participants. The rate of SWJs in AN was also found to negatively correlate with anxiety. Square wave jerk rate and anxiety were found to correctly classify groups, with an accuracy of 87% for AN participants and 95.5% for HCs. Given our current understanding of saccadic eye movements, the findings suggest a potential role of γ-aminobutyric acid (GABA) in the superior colliculus, frontal eye fields, or posterior parietal cortex in the psychopathology of AN.
Publisher: Wiley
Date: 14-02-2012
DOI: 10.1111/J.1468-1331.2011.03545.X
Abstract: Background and purpose: Niemann–Pick disease type C (NPC) is a progressive neurovisceral disorder associated with dystonia, ataxia and a characteristic gaze palsy. Neuropathological studies have demonstrated brainstem atrophy associated with neuronal inclusions and loss, and neurofibrillary tangles, although it is not known whether this pathology can be detected in vivo or how these changes relate to illness variables, particularly ocular‐motor changes. Our aim was to utilize a method for brainstem atrophy, validated in progressive supranuclear palsy (PSP), in a group of adult patients with NPC, and explore its relationship to illness variables and ocular‐motor functioning. Methods: We calculated the midbrain and pontine area, and pontine‐to‐midbrain ratio (PMR) from midsagittal images of 10 adult patients with NPC and 27 age‐ and gender‐matched controls. Measures were correlated with illness variables, and measures of horizontal saccadic functioning. Results: Pontine‐to‐midbrain ratio was 14% higher in the NPC group, but this difference was not significant. However, PMR showed a significant positive correlation with duration of illness and a measure of illness severity. Furthermore, PMR was significantly negatively correlated with saccadic peak velocity and gain, and self‐paced saccadic performance. Conclusions: Pontine‐to‐midbrain ratio was increased in adult patients with NPC compared to controls, although not to the same degree as previously described in PSP, which also presents with significant gaze palsy. These changes were driven predominantly by progressive midbrain atrophy. The strong correlation with illness and ocular‐motor variables suggests that it may be a useful marker for illness progression in NPC.
Publisher: Elsevier BV
Date: 04-2010
Publisher: Informa UK Limited
Date: 1987
Publisher: SAGE Publications
Date: 12-10-2010
Abstract: Niemann-Pick disease type C is a rare, genetic disease associated with impaired intracellular lipid trafficking and progressive neurological symptoms. Miglustat slowed disease progression in a 12-month randomized trial in juveniles and adults with Niemann-Pick disease type C, and in a parallel, noncontrolled study in affected children. Here, the authors report the open-label extension to the pediatric study. Patients aged 4 to 12 years received open-label miglustat (dose adjusted for body surface area) for an initial 12 months, during a further 12-month extension, and a long-term, continued extension phase. Efficacy assessments included horizontal saccadic eye movement, swallowing, and ambulation. Ten children completed 24 months’ treatment. Horizontal saccadic eye movement, ambulation, and swallowing were stabilized at 24 months. Analysis of key parameters of disease progression showed disease stability in 8 of 10 patients (80%). Miglustat stabilized neurological disease progression in pediatric patients with Niemann-Pick disease type C, with comparable safety and tolerability to that observed in adults and juveniles.
Publisher: Elsevier BV
Date: 09-2007
Publisher: American Society of Neuroradiology (ASNR)
Date: 19-05-2011
DOI: 10.3174/AJNR.A2490
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 08-2008
DOI: 10.1167/IOVS.08-1709
Abstract: Perceptual instability in infantile nystagmus syndrome (INS) has been reported occasionally. This study was conducted to examine the factors that influence perceptual stability in 18 in iduals with INS. The subjects were instructed to look continuously at a fixation LED centered in an image (38 degrees x 32 degrees ) at two luminance levels (3.25 and 0.46 cd/m(2), with 21% and 96% contrast, respectively) throughout all trials. A trial consisted of the fixation LED on, followed by a peripheral LED on, and then both LEDs off. Subjects then reported what they perceived. Five trials were conducted per contrast image. Eye movements were recorded with a limbal tracker. After testing, each subject completed a questionnaire to determine whether they ever had or were presently experiencing oscillopsia. Sixteen of 18 subjects reported experiencing oscillopsia on the questionnaire. In the laboratory, the percentages of trials with perceptions of motion of the LED and background were as follows: neither, 45% to 60% background only, 15% to 30% both, approximately 15% and LED only, approximately 10%. Over all trials, 14/18 and 13/17 subjects experienced oscillopsia for the low- and high-contrast images, respectively (i.e., four subjects never experienced oscillopsia). The background was frequently seen moving when both images were displayed, regardless of contrast and/or condition. Trials with and without oscillopsia did not differ between the foveation periods. Subjects with INS may experience spatially inhomogeneous oscillopsia under certain viewing conditions. The physical attributes of the stimulus, repeated trials, different conduction times, and the role of ided attention may influence a subject's perception differently.
Publisher: Elsevier BV
Date: 06-1991
DOI: 10.1016/0006-3223(91)90248-K
Abstract: The smooth pursuit responses to 5 degrees and 20 degrees/sec constant-velocity stimuli were recorded from 23 patients with schizophrenia, 16 affective disorder patients, and 21 normals using low-noise infrared oculography. Pursuit gain, catch-up saccade (CUS) rate and litude, and their interrelationships were examined. Gain in the schizophrenic patients was reduced only at 20 degrees/sec, but for both patient groups, CUS rate at 5 degrees/sec was significantly lower than in normals. Using CUS rate at 20 degrees/sec, the patient groups could be distinguished from each other (the rate for schizophrenic patients being highest, and the rate for affectives the lowest) but neither differed significantly from normals. The diagnostic groups did not differ significantly in mean CUS litude, although there was a trend for patients to have larger saccades. Gain-CUS rate correlation was strong in normals but reduced or absent in both patient groups. These results indicate that the ocular motor systems of patients with schizophrenia and affective disorders process eye position error abnormally.
Publisher: Wiley
Date: 14-09-2006
DOI: 10.1111/J.1442-9071.2006.01317.X
Abstract: To explore the meaning of amblyopia from both parents' and children's perspectives and to seek correlations between the experiential aspects of the condition and its treatment, the clinical characteristics of amblyopia and any apparent psychopathology. Children with amblyopia and their parents were engaged in semistructured in-depth interviews. Children also underwent a vision assessment and, where applicable, parents and children completed a psychological inventory, the Behaviour Assessment System for Children. Dealing with stigma and the perceptions and responses of peers were found to be of central significance to the experience of amblyopia therapy. This had adverse consequences for some children's identity and psychosocial well-being. The clinical manifestations of amblyopia did not correlate with the social implications of the condition. However, children with strabismus were noted to have significantly greater conduct and externalizing problems. Given that amblyopia can affect children's psychosocial well-being, health outcomes need to integrate both vision and psychosocial implications of treatment. Although treatment should aim to reverse amblyopia and restore visual acuity, efforts to minimise any negative psychosocial consequences of treatment should be made. A way to balance managing amblyopia and ensuring children's psychosocial well-being should to be considered by clinicians and included in treatment guidelines.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2007
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 08-2008
DOI: 10.1167/IOVS.08-1710
Abstract: To investigate the proper usage of wavelet analysis in infantile nystagmus syndrome (INS) and determine its limitations and abilities. Data were analyzed from accurate eye-movement recordings of INS patients. Wavelet analysis was performed to examine the foveation characteristics, morphologic characteristics and time variation in different INS waveforms. Also compared were the wavelet analysis and the expanded nystagmus acuity function (NAFX) analysis on sections of pre- and post-tenotomy data. Wavelet spectra showed some sensitivity to different features of INS waveforms and reflected their variations across time. However, wavelet analysis was not effective in detecting foveation periods, especially in a complicated INS waveform. NAFX, on the other hand, was a much more direct way of evaluating waveform changes after nystagmus treatments. Wavelet analysis is a tool that performs, with difficulty, some things that can be done faster and better by directly operating on the nystagmus waveform itself. It appears, however, to be insensitive to the subtle but visually important improvements brought about by INS therapies. Wavelet analysis may have a role in developing automated waveform classifiers where its time-dependent characterization of the waveform can be used. The limitations of wavelet analysis outweighed its abilities in INS waveform-characteristic examination.
Publisher: Elsevier BV
Date: 11-1988
DOI: 10.1016/0006-3223(88)90250-8
Abstract: Although a voluminous literature exists on the eye movements of schizophrenic and affective disorder patients, many of the assessments made of smooth pursuit have been qualitative in nature. Most of them have not differentiated between abnormal functioning of the smooth pursuit system and intrusion of inappropriate saccades during a smooth tracking task. Specific identification of the pursuit or saccadic defect is necessary if the origins of the abnormalities are to be understood and related to psychopathology. Analytical techniques, such as the ln(S/N) ratio, although numerical in nature, are still unable to discriminate among pursuit and saccadic defects, as shown by our analysis of simulated tracking. Thus, to understand the effects of psychiatric disorders on the ocular motor system, specific defects must be identified and quantified.
Publisher: Wiley
Date: 17-07-2009
DOI: 10.1007/S10545-009-1173-1
Abstract: We describe the differential presentation of schizophrenia-like psychosis in two siblings with the 'variant' biochemical presentation of adult Niemann-Pick disease type C. The male sibling presented with psychosis at age 16 years and cognitive and motor disturbance at age 25 years, whereas his elder sister, sharing the same mutation but showing less severe biochemical, neuroimaging and ocular motor parameters, presented with a similar schizophrenia-like illness with associated cognitive and motor disturbance at age 31 years. Their illness onset, course and response to treatment mirrors the sex dimorphism seen in schizophrenia, and is suggestive of an interaction between the neurobiology of their metabolic disorder and sex differences in neurodevelopment.
Publisher: Informa UK Limited
Date: 1985
Publisher: Wiley
Date: 10-2011
Publisher: Informa UK Limited
Date: 1985
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2009
Publisher: Springer Science and Business Media LLC
Date: 05-1988
DOI: 10.1007/BF00247595
Abstract: Coronary artery fistulae are a rare cardiovascular anomaly. Even less common are multiple fistulae involving more than 1 coronary artery. Herein we report the case of a 47-year-old woman who had fistulae from both the right coronary and left circumflex coronary arteries draining into the coronary sinus. These lesions we attempted to close percutaneously but subsequently closed surgically. We discuss diagnostic imaging approaches, along with closure indications, closure options, and outcomes.
Publisher: Cold Spring Harbor Laboratory
Date: 11-08-2020
DOI: 10.1101/2020.08.05.20158915
Abstract: Niemann-Pick type C (NPC) is a rare lysosomal storage disorder with ocular motor involvement. In a multicontinental, cross-sectional study we characterized ocular motor function in 72 genetically proven patients from twelve countries by means of video-oculography. Interlinking with disease severity, we also searched for ocular motor biomarkers. Our study protocol comprised reflexive and self-paced saccades, smooth pursuit, and gaze-holding in horizontal and vertical planes. Data were compared with those of 158 healthy controls. The Modified Disability Rating Scale, Scale for Assessment and Rating of Ataxia, Spinocerebellar Ataxia Functional Index for neurological status, and Montreal Cognitive Assessment for cognition were also performed. In contrast to previous publications and the common belief that the “downward saccadic system degenerates to greater extent than the upward one”, our measurements of vertical saccades demonstrated that the involvement in both directions was similar. Mean saccadic peak velocity to 20° stimulus was 63.5°/s (SD, 95% CIs of the mean: 59.5, [47.9-79.2]) in NPC patients and 403.1°/s (69.0, [392.0-414.2°/s]) in healthy subjects (p .001). Downward saccades yielded 51°/s (68.9, [32.7-69.3]), whilst upward 78.8°/s (65.9, [60.8-96.8]) (p .001). Vertical position smooth pursuit gain was 0.649 (0.33, [0.554-0.744]) in NPC and 0.935 (0.149 [0.91-0.959]) in HC (p .001). The number of patient-specific saccadic patterns, incl. slow-pursuit like, hypometric and staircase-pattern saccades suggest varying involvement of the saccadic system with fragmentation of the velocity profile as a sign of omnipause neuron dysfunction. Observed compensating strategies, such as blinks to elicit saccades, head and upper body movements to overcome the gaze palsy, should be used clinically to establish a diagnosis. Vertical reflexive saccades were more impaired and slower than self-paced ones. Ocular motor performance depended on age of onset and disease duration. We found that peak velocity and latency of horizontal saccades, vertical saccadic duration and litude, and horizontal position smooth pursuit can be used as surrogate parameters for clinical trials, as they showed the strongest correlation to disease severity. By comparing saccadic with pursuit movements, we showed that 98.2% of patients generated vertical saccades (both up and down) that were below the 95% confidence intervals of the controls’ peak velocity. Only 46.9% of patients had smooth pursuit gain lower than that of 95% of healthy controls. Vertical supranuclear saccade palsy and not vertical supranuclear gaze palsy is the hallmark of NPC disease. The distinction between saccadic and gaze palsy is also important in other neurodegenerative diseases and inborn errors of metabolism with ocular motor involvement, such as progressive supranuclear palsy or Gaucher disease type 3.
Publisher: Elsevier BV
Date: 12-2008
Publisher: Oxford University Press (OUP)
Date: 27-10-2022
Abstract: Identifying when recovery from a sports-related concussion (SRC) has occurred remains a challenge in clinical practice. This study investigated the utility of ocular motor (OM) assessment to monitor recovery post-SRC between sexes and compared to common clinical measures. From 139 preseason baseline assessments (i.e. before they sustained an SRC), 18 (12 males, 6 females) consequent SRCs were sustained and the longitudinal follow-ups were collected at 2, 6, and 13 days post-SRC. Participants completed visually guided, antisaccade (AS), and memory-guided saccade tasks requiring a saccade toward, away from, and to a remembered target, respectively. Changes in latency (processing speed), visual–spatial accuracy, and errors were measured. Clinical measures included The Sports Concussion Assessment Tool, King-Devick test, Stroop task, and Digit span. AS latency was significantly longer at 2 days and returned to baseline by 13-days post-SRC in females only (P & 0.001). Symptom numbers recovered from 2 to 6 days and 13 days (P & 0.05). Persistently poorer AS visual–spatial accuracy was identified at 2, 6 and 13 days post-SRC (P & 0.05) in both males and females but with differing trajectories. Clinical measures demonstrated consistent improvement reminiscent of practice effects. OM saccade assessment may have improved utility in tracking recovery compared to conventional measures and between sexes.
Publisher: Informa UK Limited
Date: 20-04-2023
Publisher: Wiley
Date: 11-2008
DOI: 10.1002/ANA.21491
Publisher: Wiley
Date: 24-05-2002
DOI: 10.1046/J.1442-9071.2002.00518.X
Abstract: The effects of a moderate alcohol dose on reflexive and volitional saccades were compared. Healthy male subjects (n = 17) made horizontal reflexive saccades, antisaccades and self-paced saccades before and after the ingestion of a body-weight-related dose of alcohol. At a mean blood alcohol concentration of 0.044%, reflexive saccade latency significantly increased although accuracy remained unimpaired at each target litude. No significant ethanol effects were noted for antisaccade accuracy and latency. Antisaccade error rates decreased significantly, likely demonstrating a learning effect. The mean rate of self-paced saccades did not significantly change post-ethanol and their accuracy was also unimpaired. All saccades share a final common pathway for their execution. It thus seems reasonable to propose that ethanol modulated connections between the posterior parietal cortex and superior colliculus to increase reflexive saccade latency. Higher-order paradigms, which require inhibition and are mediated by frontal areas, might be impaired at greater blood alcohol concentrations.
Publisher: Springer Berlin Heidelberg
Date: 2013
Publisher: Elsevier BV
Date: 06-1992
DOI: 10.1016/0006-3223(92)90155-S
Abstract: Two types of saccadic intrusions into smooth pursuit eye tracking, anticipatory saccades (AS), and square wave jerks (SWJ), were measured in 23 patients with schizophrenia, 16 patients with affective disorder, and 21 normal controls. Constant velocity (5 degrees and 20 degrees/sec) predictable targets were employed. High resolution infrared oculography was employed to record eye movements. Although most subjects had at least one SWJ, there were no significant group differences, and the highest in idual rates of SWJ were seen in the normal control group. On the other hand, AS were never seen in normals, but were present in 25%-44% of patients with either schizophrenia or affective disorder. Both patient groups had significantly more AS than controls, but the two patient groups were not significantly different.
Publisher: Wiley
Date: 12-07-2021
DOI: 10.1111/ENE.14955
Abstract: To characterize ocular motor function in patients with Niemann‐Pick disease type C (NPC). In a multicontinental, cross‐sectional study we characterized ocular‐motor function in 72 patients from 12 countries by video‐oculography. Interlinking with disease severity, we also searched for ocular motor biomarkers. Our study protocol comprised reflexive and self‐paced saccades, smooth pursuit, and gaze‐holding in horizontal and vertical planes. Data were compared with those of 158 healthy controls (HC). Some 98.2% of patients generated vertical saccades below the 95% CI of the controls’ peak velocity. Only 46.9% of patients had smooth pursuit gain lower than that of 95% CI of HC. The involvement in both downward and upward directions was similar (51°/s (68.9, [32.7–69.3]) downward versus 78.8°/s (65.9, [60.8–96.8]) upward). Horizontal saccadic peak velocity and latency, vertical saccadic duration and litude, and horizontal position smooth pursuit correlated best to disease severity. Compensating strategies such as blinks to elicit saccades, and head and upper body movements to overcome the gaze palsy, were observed. Vertical reflexive saccades were more impaired and slower than self‐paced ones. Gaze‐holding was normal. Ocular‐motor performance depended on the age of onset and disease duration. This is the largest cohort of NPC patients investigated for ocular‐motor function. Vertical supranuclear saccade palsy is the hallmark of NPC. Vertical upward and downward saccades are equally impaired. Horizontal saccadic peak velocity and latency, vertical saccadic duration and litude, and horizontal position smooth pursuit can be used as surrogate parameters for clinical trials. Compensating strategies can contribute to establishing a diagnosis.
Publisher: Public Library of Science (PLoS)
Date: 30-11-2012
Location: United States of America
No related grants have been discovered for Larry Abel.