Photovoltaic restoration of high visual acuity in rats with retinal degeneration

Patients with retinal degeneration lose sight due to gradual demise of photoreceptors. Electrical stimulation of the surviving retinal neurons provides an alternative route for delivery of visual information. We developed subretinal photovoltaic arrays to convert pulsed light into bi-phasic pulses of current to stimulate the nearby inner retinal neurons. Bright pulsed illumination is provided by image projection from video goggles and avoids photophobic effects by using near-infrared (NIR, 880-915nm) light. Experiments in-vitro and in-vivo demonstrate that the network-mediated retinal stimulation preserves many features of natural vision, such as flicker fusion, adaptation to static images, and most importantly, high spatial resolution. Our implants with 70μm pixels restored visual acuity to half of the normal level in rats with retinal degeneration. Ease of implantation and tiling of these wireless arrays to cover a large visual field, combined with their high resolution opens the door to highly functional restoration of sight.