SBIR-STTR Award

Uses of the central visual field, or foveal scotoma, due toaccidental exposure to laser light or macular disease can cause seriousimpairments in visually aided performance. Foveal scotomas also interferewith normal control of eye reactions and saccades. Feasibility is testedfor using electronic image shifting from scotomatous foveal retina tointact peripheral retina, as a compensation for central field losses. Ascotoma simulator already developed by the PI will safely duplicate andexperimentally control scotoma size, shape, and position. Visual imagesprojecting around the fovea, are masked in real-time, by feeding eyeposition signals into a computer controlled visual display, safely creatingthe appearance of a scotoma. A image shift system consists of copying thevisual image covered by the scotoma, and re-displaying that image at aneccentric viewing position on peripheral retina. Feasibility tests use twocriteria: 1) the effectiveness of image shifting in compensating forperformance losses due to foveal scotoma, and 2) the occurrence and effectof abnormal eye movements created by image shifting. Independent variablesinclude the shift image size, scotoma size, selection of peripheral viewingsite, and synchrony of shifting with eye movements. The shift method iscompared with unaided eccentric viewing.

Foveal visual loss from exposure to lasers, or progressive macular disease, cause impairments in visual search, reading and performance by afterimages or injury to high resolution central retina and interfere with control of eye fixations and saccades. Development of an electronic aid is proposed as a compensation, suitable for vehicle and person portability. Development involves use of a scotoma simulator method developed by the PI to experimentally control foveal scotoma size, shape, and position in normal subjects with a real-time computer controlled display. The electronic aid is switched into the system by mixing signals from simulator and aid, through a software. The aid compensates for visually guided performance losses expected to accompany sudden or progressive visual loss, and it will be useful in reducing abnormal eye movements from 1) loss of foveal oculomotor control and 2) naturally occurring but inefficient adaptations. Variables and features include adjustment for scotoma size, selection of alternative retina for visual acquisition, and synchrony of the aid's operation to match parameters of the visual system. Aided and unaided compensation are compared as well as a range of operational conditions to evaluate the aid's effectiveness.