Electronic "photoreceptors" enable prosthetic vision with acuity matching the natural resolution in rats

Abstract Localized stimulation of the inner retinal neurons for high-acuity prosthetic vision requires small pixels and minimal cross-talk from neighboring electrodes. Local return electrodes within each pixel can limit the crosstalk, but they over-constrain the electric field, thus precluding the efficient stimulation with subretinal pixels smaller than 50 μm. Here we demonstrate a high-resolution prosthetic vision based on a novel design of a photovoltaic array, where field confinement is achieved dynamically, leveraging the adjustable conductivity of the diodes under forward bias to turn the designated pixels into transient returns. We validated computational modeling of the field confinement in such an optically-controlled circuit by ex-vivo and in-vivo measurements. Most importantly, we demonstrated that by using this strategy, the grating acuity of prosthetic vision with 20 μm pixels matches the 28 μm limit of the natural visual acuity in rats. This method will enable customized field shaping for each patient based on individual retinal thickness and distance from the implant, paving the way to prosthetic vision with acuity as high as 20/80 in atrophic macular degeneration.