Training to Modify Fixational Eye Movements for Optimizing Visual Performance in People With Central Vision Loss

People with central vision loss almost all have exaggerated fixational eye movements when compared with people with normal vision (e.g. larger amplitudes of microsaccades and ocular drifts). Central vision loss primarily results from eye diseases or disorders that affect the macular region of the retina, such as age-related macular degeneration (AMD) and Stargardt disease. The clinical wisdom is that exaggerated fixational eye movements are detrimental to vision. This forms the basis of the increasing number of clinical trials that use fixation stability (variability of eye positions during fixation) as an outcome measure to evaluate the effectiveness of interventions on age-related macular degeneration or other retinal diseases, despite the lack of causal evidence supporting or refuting a relationship between fixational eye movements and functional vision. If excessive fixational eye movements are indeed detrimental to vision for people with central vision loss, can we reduce the amount of their fixational eye movements, thus improve their fixation stability? And if so, does that lead to improved functional vision? The goal of this study is to examine the hypothesis that retinal image motion due to abnormal fixational eye movements can be modified through fixation training, with accompanied improvements in functional vision as a result.