Retraining Eye Movement in People with Age-Related Macular Degeneration

Age-related macular degeneration (AMD) can damage the cone photoreceptors found in the centre of the retina called the fovea. When these photoreceptors are badly damaged, the eye loses the ability to see colours or fine detail, however photoreceptors in the outer area of the retina usually remains undamaged. Even with severe macular degeneration, people retain their peripheral vision.

In people with normal vision, the gaze is fixated on the fovea, since this area of the retina provides the highest quality vision. However, in people where the central vision has been damaged, the eye naturally tries to use other areas of the retina that are less damaged. People with advanced AMD may turn their head or move objects trying to maximize their use of the undamaged retina.

Vision researcher Martin Steinbach and low vision ophthalmologist, Samuel Markowitz, study ways to help people with AMD maximize the person’s remaining vision. They have worked extensively with a piece of equipment called a microperimeter which measures light sensitivity at various points on the retina. Using this tool, they can identify undamaged parts of a person’s vision, and a particular place used for fixating, called the “preferred retinal locus.”

                                    Dr. Steinbach and staff measure a person’s preferred retinal locus.

Retraining aims to help people fixate their gaze by moving the preferred retinal locus to a more useful location, improving their ability to read and perform other visual functions. Therapy helps patients learn to locate the “preferred retinal locus,” and to maintain their gaze in this area, a process called fixation stability. Donald K Johnson Eye Institute scientists have become leaders in studying and understanding fixation stability. This research team has developed biofeedback methods to help move and maintain the fixation point in the most desirable location.

Dr. Steinbach has also worked to develop other methods of visual rehabilitation less reliant on expensive testing equipment. His recent efforts use techniques called ‘perceptual learning’ which can improve function for many. People are taught to read text and to focus either above or below the line, depending on their vision. This helps them find and learn to use the most effective preferred retinal locus.