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Retinal dystrophies and age-related macular degeneration related to photoreceptor degeneration can cause blindness. In blind patients, although the electrical activation of the residual retinal circuit can provide useful artificial visual perception, the resolutions of current retinal prostheses have been limited either by large electrodes or small numbers of pixels. Here, we report the evaluation, in three awake non-human primates, of a previously reported near-infrared-light-sensitive photovoltaic subretinal prosthesis. We show that multi-pixel stimulation of the prosthesis within radiation-safety limits enabled eye tracking in the animals, that they responded to the stimulations in the direction of the implant with repeated saccades, and that the implant-induced responses were present two years after device implantation. Our findings pave the way for the clinical evaluation of a 378-electrode prosthesis in patients affected by dry atrophic age-related macular degeneration.

. Purpose:  To determine the threshold charges needed for eliciting visual perceptions through acute electrical stimulation of the human retina in patients suffering from retinitis pigmentosa, using an epiretinal microelectrode array. Methods:  In a multicentre study, 20 patients (average age 55 years) with visual acuities ranging from 4/200 to no light perception were included. The stimulation procedure was performed during a pars plana vitrectomy, for a maximum of 45 min, by using a microcontact film with IrOx electrodes connected by cable to a current generator. After repeated stimulation and threshold charge determination, the microelectrode array was removed. Results:  Nineteen of 20 patients stated in the postoperative interviews that they experienced one or more visual perceptions with close time correlation to single stimulation events. Minimum threshold charges needed to generate visual perceptions could be measured and verified in 15 patients. The charge level ranged from 20 to 768 nC with single or multiple electrodes. One patient suffered a retinal detachment during the procedure; this patient’s retina was successfully reattached. There were no further adverse reactions observed during the 3‐month follow‐up. Conclusion:  Acute epiretinal stimulation of the human retina, using a microelectrode array, can elicit visual perceptions in blind patients with retinitis pigmentosa.

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