Saccadic adaptation in the presence of artificial central scotomas

Age-related macular degeneration (AMD) is characterized by the degradation of the macula resulting in poor central vision and difficulty performing daily tasks. Helping AMD patients optimally utilize their residual visual function is the focus of current rehabilitative strategies. Here we test whether saccadic adaptation is possible in the presence of an artificial central scotoma and if so, to what extent. The ultimate goal is to use saccadic adaptation to train patients in performing saccade re-referencing to better utilize their intact peripheral vision; patients would learn to make saccades to direct their preferred peripheral locus to the object of interest rather than the inutile fovea. We measured saccadic adaptation in healthy young participants using a central gaze-contingent artificial scotoma in two experiments, using a conventional double-step paradigm for both experiments, testing twelve and thirteen subjects respectively. Experiment 1 tested backward adaptation using a visible as well as an invisible 3° diameter scotoma. Experiment 2 consisted of forward adaptation using a 2° and a 4° invisible scotoma. We thus explored both backward and forward adaptation (known to involve different mechanisms), different-sized central scotomas, and different visibilities of scotomas. We found that in all scotoma conditions, participants adapted to similar amounts compared to control conditions without scotomas. We conclude that saccadic adaptation can occur sufficiently with central scotomas. Our results support the idea that central vision of the target is unnecessary for adaptation and that saccadic adaptation is driven primarily by peripheral retinal error.