This project is designed to evaluate the feasibility of a visual prosthesis for totally blind individuals by stimulating chronically implanted microelectrodes in the visual cortex. As reported last year, a 42 year old woman who has been blind for 22 years was implanted with an array of 38 electrodes in the visual cortex. Stimulation of individual electrodes produced sensations of light called phosphenes. The results suggest that it may be possible to produce a useful visual prosthesis if more electrodes are implanted. A new protocol for implanting up to 256 microelectrodes in the visual cortex has been approved by the Institute's Human Review Board. A 256-channel, microprocessor-controlled stimulation system has been constructed and is now undergoing final evaluation prior to testing with animals. A camera interface that will allow stimulation of the electrode array with visual image is nearing completion. A new laser system can remove Parylene-C insulation from the electrodes and provide a much better tip exposure than has been possible with any other technique. The new head-mounted, multicontact connector, developed in conjunction with PI Medical, is undergoing final bench testing before animal implantation. The next patient should be implanted during FY 1995.
