Retinal prosthesis

Abstract

The retinal prosthesis is intended to replace lost or damaged photoreceptors by directly stimulating the inner retinal layer. It is indicated for outer retinal diseases such as agerelated macular degeneration and retinitis pigmentosa. A video camera external to the eye captures the visual environment and electronic image-processing circuitry reduces the resolution and complexity of the image. The image data are fed via a telemetry link to a decoder chip implanted in the eye. The decoder chip converts the image data and produces the necessary pattern of small electrical currents to be applied to the retina through a two-dimensional array of electrodes positioned at the inner retinal surface. Each individual electrode directly stimulates the underlying retinal neurons, resulting in perception of a dot of light at a point in the visual field corresponding to the retinal location. Simultaneous activation of multiple electrodes in the array creates a pattern of individual dots of light. Encouraging results of feasibility studies have culminated in a phase I clinical trial in three patients.