Patients with age-related macular degeneration can learn to use different areas of their retinas to compensate for central vision loss, according to a study in the December issue of Restorative Neurology and Neuroscience. The authors suggest that many AMD patients use eccentric viewing to adopt a preferred retinal location (PRL) outside of the damaged fovea, which might foster permanent cortical reorganization and allow for improved sight.
The authors presented 13 subjects with a series of visual tests and training exercises that stimulated their peripheral retinal regions. During this testing, the subjects underwent functional magnetic resonance imaging to measure brain activity. The authors found that when patients PRLs were stimulated, they exhibited increased brain activity in parts of the visual cortex that are normally reserved for central vision function.
The authors conclude that large-scale cortical reorganization is possible in patients with AMD, and that this reorganization is related to functional modifications in patient behavior.
If studied further, cortical reorganization in response to retinal diseases, such as AMD, could change the world of vision and optometry as we know it, says Stacy Schorner, O.D., who specializes in neuro-ophthalmic disorders at University Eye Associates, in Charlotte, N.C. If low vision training could play a role in the reorganization of neural connections, this could change the protocol for optometric referrals to other specialists and be a revolutionary advancement for those with devastating central vision loss.
One major concern, however: the cost of testing and low vision training. Hopefully, insurance companies would be willing to reimburse patients for a service that will likely be very costly, Dr. Schorner says.
Schumacher EH, Jacko JA, Primo SA, et al. Reorganization of visual processing is related to eccentric viewing in patients with macular degeneration. Restor Neurol Neurosci 2008; 26(4-5):391-402.