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M. Humayun, R.J. Greenberg, B.V. Mech, D. Yanai, M. Mahadevappa, G. van Boemel, G.Y. Fujii, J.D. Weiland, E. de Juan, Jr.; Chronically Implanted Intraocular Retinal Prosthesis in Two Blind Subjects . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4206.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To study the feasibility of implanting a retinal prosthesis in humans with bare or no light perception vision from retinitis pigmentosa (RP). Methods: The FDA granted an IDE and USC-IRB approved the study protocol. After obtaining informed consent, the subjects were screened using visual psychophysical perception testing, electrophysiology, ophthalmic photography, and scanning laser ophthalmoscopy. Two subjects who met the visual criteria were implanted with a Second Sight Model 1 retinal stimulator in the worse eye. The implant consisted of an extraocular microelectronic device and an intraocular electrode array, connected by a multiwire cable. The microelectronic case was positioned above the ear, in a pocket drilled in the temporal bone. The cable was positioned underneath the temporalis muscle, encircled the eye once, and entered the intraocular cavity via a pars plana incision. The electrode array was affixed to the retina with a single tack. The electrode array consisted of a 4x4 grid of platinum electrodes embedded in silicone rubber. The implant was wirelessly activated using an external controller. Electrical stimulus pattern was determined by a custom computer interface or video camera. Results: Both devices were implanted without complication. Subject 1 (S1) has been implanted for 10 months and subject 2 (S2) for 4 months. Both subjects reported the perception of light on all 16 electrodes. The electrical stimulus thresholds ranged from 28-949 uA in S1 and 43-679 uA in S2. Using a head mounted video camera as a source for the stimulus pattern, both subjects demonstrated the ability to detect room lights on or off with 100% accuracy (10/10 and 10/10). Using the camera, S1 could correctly identify the orientation of a tumbling L (four alternative, forced choice) in 15 of 20 attempts (75%). In S1, evoked potentials were obtained (N1 – 20 ms, P1 – 40 ms, N1-P1 amplitude 4.49-8.78 uV). With the implant turned off, visual acuity remained at the preoperative levels. The subjects report little discomfort from the presence of the implant. Conclusions: Two test subjects, blind from RP, can see visual perceptions that correlate to electrical stimulus from a chronically implanted retinal prosthesis. Subjects have used a camera driven stimulus to detect light and recognize simple shapes.
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