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A visual prosthetic or '''bionic eye''' is a form of Neural Prosthesis intended to partially restore Lost Vision or amplify existing Vision . It usually takes the form of an externally-worn camera that is attached to a stimulator on the retina, Optic Nerve , or in the visual cortex, in order to produce perceptions in the visual cortex. HISTORY Scientific research since at least the 1950s has investigated interfacing electronics at the level of the Retina , Optic Nerve , Thalamus , and Cortex . Visual prosthetics, which have been implanted in patients around the world both acutely and chronically, have demonstrated proof of principle, but do not yet offer the visual acuity of a normally sighted eye. Biological considerations The ability to give sight to a blind person via a bionic eye depends on the circumstances surrounding the loss of sight. For retinal prostheses, which are the most prevalent visual prosthetic under development (due to ease of access to the retina among other considerations), vision loss due to degeneration of photoreceptors (retinitis pigmentosa, choroideremia, geographic atrophy macular degeneration) is the best candidate for treatment. Candidates for visual prosthetic implants find the procedure most successful if the optic nerve was developed prior to the onset of blindness. Persons born with blindness may lack a fully developed optical nerve, which typically develops prior to birth. Technological considerations Visual prosthetics are being developed as a potentially valuable aide for individuals with visual degradation. The visual prosthetic in humans remains investigational. ONGOING PROJECTS Argus Retinal Prosthesis Drs. Mark Humayun and Eugene DeJuan at the Doheny Eye Institute ( USC ) were the original inventors of the active epi-retinal prosthesis 1 and demonstrated Proof Of Principle in acute patient investigations at Johns Hopkins University in the early 90s. In the late 90s the company Second Sight was formed to develop a chronically implantable retinal prosthesis. Their first generation implant had 16 electrodes and was implanted in 6 subjects between 2002 and 2004. Five of these subjects still use the device in their homes today. These subjects, who were all completely blind prior to implantation, can now perform a surprising array of tasks using the device. More recently, the company announced that it has received FDA approval to begin a trial of its second generation, 60 electrode implant, in the US.2 3 Additionally they have planned clinical trials worldwide, all getting underway in 2007. Three major US government funding agencies (National Eye Institute, Department of Energy, and National Science Foundation) have supported the work at Second Sight and USC. Microsystem-based Visual Prosthesis (MIVIP) |
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