Objective. Clinical trials previously demonstrated the spectacular capacity to elicit visual percepts in blind patients affected with retinal diseases by electrically stimulating the remaining neurons on the retina. However, these implants restored very limited visual acuity and required transcutaneous cables traversing the eyeball, leading to reduced reliability and complex surgery with high postoperative infection risks. Approach. To overcome the limitations imposed by cables, a retinal implant architecture in which near-infrared illumination carries both power and data through the pupil is presented. A high efficiency multi-junction photovoltaic cell transduces the optical power to a CMOS stimulator capable of delivering flexible interleaved sequential stimulation through a diamond microelectrode array. To demonstrate the capacity to elicit a neural response with this approach while complying with the optical irradiance safety limit at the pupil, fluorescence imaging with a calcium indicator is used on a degenerate rat retina. Main results. The power delivered by the laser at safe irradiance of 4 mW/mm2 is shown to be sufficient to both power the stimulator ASIC and elicit a response in retinal ganglion cells (RGCs), with the ability to generate of up to 35 000 pulses per second at the average stimulation threshold. Significance. This confirms the feasibility of wirelessly generating a response in RGCs with a digital stimulation controller that can deliver complex multipolar stimulation patterns at high repetition rates.
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