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James D. Weiland; Electronic retinal prosthesis: concepts and clinical results. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1994.
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Presentation Description :
Retinal prostheses have progressed from laboratory and early clinical experiments, to medical devices approved for sale by the FDA and European Union. This seminar will review the history of retinal prostheses for the blind, focusing in particular on the Argus II implant system, experiments on-going to improve the function of this device, and differences in the visual system of blind people that present challenges to implementation. The clinical trials have shown that individuals who have at best light perception vision, can use spatial information from the retinal prosthesis to detect motion, locate objects, and read letters. Improvements in navigation and mobility have been noted. Experiments in my lab have focused on the use of both human implant patients and animal models of blindness to investigate significant issues facing retinal prostheses. The ability to perceive forms has been inconsistent in the implant patients. Form vision requires the ability to combine percepts from individual electrodes into shapes. An important aspect of form vision is limiting the size of each individual percept to an area near the electrode. In both human subjects and in rodent model retina, we have demonstrated that longer pulses (20 ms) evoke focal responses, while shorter pulses (1-2 ms) evoke elongated responses, the latter being less desirable. Electrophysiological studies of degenerated retina have shown aberrant cell behavior after photoreceptor degeneration that suggests modification to the inner retinal circuitry may influence retinal sensitivity to electrical stimulation. In human studies, cross-modal plasticity studies have demonstrated how the visual cortex of blind individuals is activated by non-visual (tactile) input. How the brain adapts first to blindness and then to vision restoration will have profound impact on the rehabilitation strategies used for retinal prostheses.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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