Recent success in the development of a prosthesis for the deaf patient encouraged several groups of scientists to develop and investigate a visual prosthesis. Visual prosthesis are based on neuronal electrical stimulation at different locations along the visual pathways, and three localizations of visual prosthesis are being researched, retina, optic nerve, and cortex. Retina and optic nerve implants may restore vision in patients with progressive retinal degenerations by means of electrical stimulation of visual pathway neurons. Cortex prosthesis may restore vision in a greater number of blind patients due to the more posterior location in the visual pathway. While major advances have been made in the field of visual prosthesis for the blind, a number of key questions remain to render a visual prosthesis feasible. Yet, investigation is justified regarding the long-term effects and functioning of the various electronic implants. Here we review shortly the rationale for such treatment, the three different possibilities of stimulating the visual pathway, and what are the challenges yet to be surpassed.
Macular degeneration; Aging; Electrodes, implanted; Prosthesis implantation; Retina; Retinitis pigmentosa; Visual cortex; Electric stimulation; Optic nerve; Glaucoma
