Bionic Eye

Retinal implants restoring rudimentary vision

Overview

A bionic eye, or visual prosthesis, is an implanted device that attempts to restore a degree of vision by electrically stimulating the visual system in people with profound blindness. Retinal prostheses rely on surviving inner retinal cells in diseases such as retinitis pigmentosa, where the photoreceptors are lost. The Argus II, developed by Second Sight, used a camera mounted on glasses to send signals to an electrode array placed on the retinal surface, and it received United States approval in 2013 for advanced retinitis pigmentosa. Recipients typically gained the ability to perceive light, locate large objects, and detect motion, but not to read ordinary print, and the device was later discontinued. Subretinal implants, such as the Alpha IMS and the PRIMA photovoltaic system, place light sensitive arrays beneath the retina, and PRIMA has been studied in geographic atrophy due to macular degeneration. Other approaches stimulate the optic nerve or the visual cortex directly, bypassing the eye altogether. The resolution of current devices is limited by the number and size of electrodes, and visual prostheses remain an area of active research.