gms | German Medical Science

Objective: The benefits of retinal prostheses are limited by the restricted visual field and the coarse resolution restored. To overcome these limitations, we propose an approach which combines high-resolution standalone stimulation through photovoltaic organic pixels and tuning of the epiretinal stimulation parameters, enabling both a large retinal coverage and a focal stimulation of the retinal ganglion cell (RGC) layer.

Materials and methods: We stimulated Rd10 explanted retinas with miniaturized organic photovoltaic pixels and we quantitatively and spatially assessed RGCs responses from single-unit extracellular recordings. In addition, the responses of inner retinal cells and RGCs were assessed using a biophysical model of the retina.

Results: Single pixel illumination elicited direct and network-mediated RGCs responses. The latter was exposure, duration, waveform and frequency sensitive. Under single pixel stimulation, RGCs exhibited a 119 µm-diameter photovoltaic receptive field, which can be focused thanks to the recruitment of the AC inhibitory layer.

Discussion: Outcome evaluations designate indirect epiretinal stimulation as a promising strategy to overcome the current resolution challenges in epiretinal prostheses. Our approach combining high pixel density together with stimulation parameters favouring the natural lateral inhibition could significantly improve the usefulness of prosthetic vision.

Acknowledgment: This work was supported by École Polytechnique Fédérale de Lausanne, Medtronic, Fondation Mercier pour la science, Velux Stiftung (Project 1102) and Gebert Rüf Stiftung (Project GRS-035/17).