Penetrative Optic Nerve-Based Visual Prosthesis Research

A number of research groups around the world have been dedicated to restoring some functional vision for blind patients through visual prostheses. The C-sight project (Chinese Project for Sight) proposed a visual prosthesis with penetrative stimulating electrode array implanted into the ON as a neural interface to couple the encoded electrical stimuli for vision recovery, since then a decade of effort has been devoted to the development of the first-generation prototype. In this article, the outcomes of this approach and its status quo were briefly summarized and introduced from different perspectives. Besides hardware system and surgical methods description, the cortical response characteristics in response to penetrating ON stimulation in in vivo animal experiments were extensively introduced. Firstly, as a widely used methodology of evaluating the effect of a certain electrical stimulus, the basic spatiotemporal properties of the electrically evoked cortical potentials (EEPs) elicited by penetrating ON stimulation were investigated. Secondly, the exact implantation sites of ON electrode array were considered and evaluated taking account of realizing fine visuotopic correspondence between ON electrical stimulation sites and the visual field. Thirdly, the optimal stimulus parameters were explored, as well as the relationship between response properties of electrical vs. visual stimulation. Furthermore, several potential future directions of this approach were also briefly discussed.