Visual Prostheses and the Retinal Implant Project :: Biology Essays Research Papers

Visual Prostheses and the Retinal Implant Project Visual percepts are the final product of a rich interplay of stimulus processing that occurs without the intervention of one's consciousness. While this is a fascinating issue to consider, especially as it pertains to the philosophical and practical definitions of ideas like the "self," the converse is equally interesting to me. In this modern era of exploding technological ingenuity, the sum of which is a product of the conscious brain, increasingly more opportunities exist for the brain to design the input it receives. One method by which this occurs is observable in the treatment of visual pathologies. A development of particular interest to me is the use of visual prosthetic devices in the treatment of some forms of progressive blindness. Research in this area raises numerous conflicts within the realm of bioengineering, but promises, at least, to challenge the boundaries of current microtechnology and instigate further integration of the rapidly expanding fields of electronics a nd medicine. In 1988, a multidisciplinary research team called the "Retinal Implant Project," spanning the knowledge bases of Harvard Medical School, the Massachusetts Eye and Ear Infirmary, and the Massachusetts Institute of Technology's Department of Electrical Engineering and Computer Science, was formed with the explicit goal of creating an intraocular retinal prosthetic device to combat the effects of certain types of progressive blindness (4). The prostheses are intended to stimulate retinal ganglion cells whose associated photoreceptor cells have fallen victim to degradation by macular degeneration or retinitis pigmentosa, two currently incurable but widespread conditions (2). Their most recent work has been to orchestrate short-term clinical trials in which blind volunteers receive a temporary intraocular prosthetic implant and undergo a series of tests to determine the quality of visual percepts experienced over a two- to three-hour period (2). The leaders of the Retinal Implant Project, while enthusiastic about their progress, do not anticipate the realization of a workable prosthetic within the next five years (2). The goal of retinal prosthetic proposed by the collaborators is to bypass degenerate photoreceptors by providing electrical stimulation directly to the underlying ganglion cells (2,3,4,5). The ganglion cell axons compose the optic nerve, which travels from the eye and terminates in various regions of the brain, where the combined input is processed along multiple routes and ultimately results in the experience of sight (4). Ganglion cell excitation will be accomplished by attaching a two-silicon-microchip system onto the surface of the retina, which will be powered by a specially designed laser mounted on a pair of glasses worn by the patient (4,5).