Intraocular retinal prosthesis: microelectronics meets medicine

Retinitis Pigmentosa (RP) and Age-Related Macula Degeneration (AMD) are incurable retinal diseases that result in profound vision loss due to degeneration of the light sensing photoreceptor cells. Retinitis pigmentosa has an incidence of I in 4000 live births, whereas, 200,000 eyes are blinded each year by age related macular degeneration. Since the late 1980's, medical doctors and scientists at the Doheny Eye Institute/University of Southern California (formerly at Johns Hopkins University) and engineers at North Carolina State University have been investigating the possibility of restoring sight to this subset of blind patients by developing an electronic retinal implant. As shown in a figure, the prototyping implant (Multiple Artificial Retina Chip Set or MARC) will replace the functionality of photoreceptor layer by directly providing electrical stimulation to the surviving neurons of the retina. Thus, by capturing light and electrically stimulating the next layers of neurons in the visual pathway (i.e. the bipolar and/or ganglion cell layer of the retina), useful sight to the blind affected by retinal diseases such as RP and AMD can be restored. Patients afflicted with RP or AMD would be the largest groups to benefit from such a biomedical advance.