Properties Of Human Photoreceptors Measured Using A Scanning Laser Ophthalmoscope To Illuminate And Image The Retina
Funder
National Health and Medical Research Council
Funding Amount
$352,000.00
Summary
Vision begins with the detection of light by the rod and cone photoreceptors in the retina lining the interior of the eye. Although much is already known about the way that light is detected and the signals are processed, a great deal remains to be learned. Some of the outstanding questions could be answered using modifications to a relatively new instrument called a scanning laser ophthalmoscope (SLO) which provides images of the interior of the eye. The aims of this project are to develop a mo ....Vision begins with the detection of light by the rod and cone photoreceptors in the retina lining the interior of the eye. Although much is already known about the way that light is detected and the signals are processed, a great deal remains to be learned. Some of the outstanding questions could be answered using modifications to a relatively new instrument called a scanning laser ophthalmoscope (SLO) which provides images of the interior of the eye. The aims of this project are to develop a modified SLO, which is able to measure the levels of visual pigment (rhodopsin) in the living eye, which is also able to deliver visual stimuli to the eye, and which finally is extended to use adaptive optics so that it can image and excite individual cone photoreceptors. Using this device, we will be able to measure the regeneration of visual pigment following exposures to intense illumination, to help explain the slow recovery of visual sensitivity after intense light. We will also be able to measure the electroretinogram (ERG) from localized retinal areas, to investigate how the properties of the photoreceptor cells vary across the retina. And finally we will be able not only to visualize the individual tiny cone photoreceptors, but also to stimulate them selectively, so that we can determine the responses of the different classes of cone (red-, green-, and blue-sensitive cones) in the living human eye.Read moreRead less
The aim of this project is to improve our understanding of the role that increased eye pressure (intraocular pressure or IOP) plays in the development of glaucoma-related nerve death and associated vision loss. Despite being the second leading cause of vision loss in Australia, our understanding of the factors that damage nerves in the eye (the ganglion cells that carry visual information to the brain) in glaucoma remains incomplete. For example, elevated eye pressure is a well-established risk ....The aim of this project is to improve our understanding of the role that increased eye pressure (intraocular pressure or IOP) plays in the development of glaucoma-related nerve death and associated vision loss. Despite being the second leading cause of vision loss in Australia, our understanding of the factors that damage nerves in the eye (the ganglion cells that carry visual information to the brain) in glaucoma remains incomplete. For example, elevated eye pressure is a well-established risk factor for glaucoma, but as many as half of those with glaucoma do not have high eye pressure. Clinical data suggests that pressure fluctuations (or spikes), which go unnoticed in routine clinical check ups, may be involved in glaucoma onset and progression. To date there has been no direct evidence to support this contention. This project aims to use a novel experimental model of pressure elevation in rodents to consider this possibility. By measuring the eye's electrical response to a flash of light it is possible to sensitively assess how pressure spikes, that are known to occur with regularity in humans, might affect the health of retinal ganglion cells. Anatomical measures will also be used to establish the sequence of events that cause cellular damage. This knowledge is an important public health issue, because it will improve understanding of the risk factors for the development of glaucoma. The results may lead to improvements in detection and treatment strategies such as closer monitoring for pressure spikes and more aggressive treatment for those who show greater variability in their eye pressures.Read moreRead less
INcidence And Progression Of Retinal Microvascular Signs In An Older Australian Cohort
Funder
National Health and Medical Research Council
Funding Amount
$62,022.00
Summary
This project aims to investigate the evolution of retinal microvascular signs and associated factors in an older, general population. 1. To investigate the 5-year and the 10-year incidence, progression and regression of retinal vascular wall signs in an older Australian population; 2. To relate the incidence, progression and regression of retinal vascular wall signs to cardiovascular risk factors (a: age, blood pressure; b: metabolic factors such as BMI, lipids and glucose levels); 3. To investi ....This project aims to investigate the evolution of retinal microvascular signs and associated factors in an older, general population. 1. To investigate the 5-year and the 10-year incidence, progression and regression of retinal vascular wall signs in an older Australian population; 2. To relate the incidence, progression and regression of retinal vascular wall signs to cardiovascular risk factors (a: age, blood pressure; b: metabolic factors such as BMI, lipids and glucose levels); 3. To investigate the incidence, progression and regression of retinal vascular wall signs in relation to inflammatory markers (white cell count, fibrinogen, hematocrit, platelet count); 4. To investigate the incidence, progression and regression of retinal vascular wall signs in relation to medication use (a: anti-hypertensive medications; b: aspirin and other NSAIDs; c. steroid use); 5. To relate the incidence, progression and regression of retinal vascular wall signs to specific lifestyle behaviours (alcohol consumption, smoking, exercise); 6. To investigate the incidence, progression and regression of retinal vascular wall signs and hormone replacement therapy use in women.Read moreRead less
A Multicentre Randomised Clinical Trial Of Laser Treatment Plus Intravitreal Traimcilone For Diabetic Macular Oedema
Funder
National Health and Medical Research Council
Funding Amount
$529,500.00
Summary
A diagnosis of diabetes immediately confers a 25 fold increase in a person's risk of blindness. The macula is the vision centre of the retina, which is like the film in a camera. In people with diabetes, swelling of the macula (macular oedema) due to leakage of retinal blood vessels is the commonest cause of loss of vision. Laser treatment is proven to be helpful in reducing the risk of vision loss in eyes with diabetic macular oedema (DMO), but it does not work in 40% of cases. Injection of slo ....A diagnosis of diabetes immediately confers a 25 fold increase in a person's risk of blindness. The macula is the vision centre of the retina, which is like the film in a camera. In people with diabetes, swelling of the macula (macular oedema) due to leakage of retinal blood vessels is the commonest cause of loss of vision. Laser treatment is proven to be helpful in reducing the risk of vision loss in eyes with diabetic macular oedema (DMO), but it does not work in 40% of cases. Injection of slow release steroids is an emerging revolutionary treatment for DMO. We are the first in the world to perform a randomised clinical trial of triamcinolone injection into the eye with DMO that has failed laser treatment. A randomised clinical trial is when an equal number of eyes are randomly allocated to the treatment and placebo (no treatment) groups, so that none of the patients or the doctors knows whether each particular eye is receiving treatment or placebo. The preliminary results of our study in progress have proved that, at least in the short term, intravitreal triamcinolone (IVTA) leads to reduction of macular oedema and improved vision. We now propose a two year randomised clinical trial to test whether the combination of IVTA with laser treatment will result in a further improvement in vision in eyes with DMO. We are in a unique position to conduct such a study, having recently concluded the world's first randomised clinical trial of IVTA for wet age-related macular degeneration in 151 eyes. We have extensive experience of IVTA's significant but manageable adverse event profile. The Australian Retinal Collaboration is a group of academic retinal specialists who are committed to attaining the highest possible standards in clinical research in Australia for common blinding conditions of the retina. The results of the proposed study are likely to lead directly to a reduction of the risk of vision impairment and blindness in people with diabetes.Read moreRead less
Neuroprotection In A Model Of Chronic Ocular Hypertension
Funder
National Health and Medical Research Council
Funding Amount
$264,221.00
Summary
Damage can occur to nervous tissues like the retina and brain when there is a reduction in the blood supply. This can occur in the eye disease, glaucoma, in which the pressure inside the eye is elevated. This serious condition often results in blindness. Much of the neuronal damage is thought to be due to the release of an excess of glutamate. Glutamate is a chemical (neurotransmitter) that nerves use to communicate with each other, but it is toxic to nerves when present at high concentrations. ....Damage can occur to nervous tissues like the retina and brain when there is a reduction in the blood supply. This can occur in the eye disease, glaucoma, in which the pressure inside the eye is elevated. This serious condition often results in blindness. Much of the neuronal damage is thought to be due to the release of an excess of glutamate. Glutamate is a chemical (neurotransmitter) that nerves use to communicate with each other, but it is toxic to nerves when present at high concentrations. This project will utilise a new model of glaucoma to investigate the mechanisms that regulate the concentration of glutamate in the retina. If these mechanisms could be made to work more efficiently, they may prevent the build-up of the glutamate and therefore prevent damage to the nerve cells. Understanding these mechanisms will aid in the development of an effective treatment to prevent visual loss in the 150,000 Australians who suffer from glaucoma.Read moreRead less
Blindness exerts major physical, emotional and economic constraints and hardship upon the sufferer. Transplant surgery can restore vision to many people who are visually impaired as a result of disease affecting the front of the eye. The transplant itself is taken from the eye of a person who has died, after consent from the donor's family. Our goal is to improve the outcome for patients who require transplants of tissue to the front of the eye, in order to restore their vision or to relieve pai ....Blindness exerts major physical, emotional and economic constraints and hardship upon the sufferer. Transplant surgery can restore vision to many people who are visually impaired as a result of disease affecting the front of the eye. The transplant itself is taken from the eye of a person who has died, after consent from the donor's family. Our goal is to improve the outcome for patients who require transplants of tissue to the front of the eye, in order to restore their vision or to relieve pain. Our work is predicated on the finding that unwanted immune responses are the major cause of graft failure in such patients. The recipient recognizes the grafted tissue as being foreign, and rejects it. Treatment with conventional systemic drugs appears to hold little promise for further improvements in outcome, but gene therapy applied to the donor tissue may provide a safe and effective way of reducing transplant failure. Gene therapy can be undertaken on the donor tissue in the laboratory, prior to transplantation surgery. In this project, we will assess the suitability of a new method of modifying the transplant. All of the work will be performed on the laboratory bench, or in experimental animals.Read moreRead less