Aided recovery from Visual Loss

Uses of the central visual field, or foveal scotoma, due to accidental exposure to laser light or macular disease can cause serious impairments in visually aided performance. Foveal scotomas also interfere with normal control of eye reations and saccades. Feasibility is tested for using electronic image shifting from scotomatous foveal retina to intact peripheral retina, as a con\mpensation for central field losses. A scotoma simulator already developed by the PI will safely duplicate and experimentally control scotoma size, shape, and position. Visual images projecting around the fovea, are masked in real-time, by feeding eye position signals into a computer controlled visual display, safely creating the appearance of a scotoma. A image shift system consists of copying the visual image covered by the scotoma, and re-displaying that image at an eccentric viewing position on peripheral retina. Feasibility tests use two criteria: 1) the effectiveness of image shifting in compensating for performance losses due to foveal scotoma, and 2) the occurrence and effect of abnormal eye movements created by image shifting. Independent variables include the shift image size, scotoma size, selection of peripheral viewing site, and synchrony of shifing with eye movements. The shift method is compared with unaided eccentric viewing.