Artificial vision: needs, functioning, and testing of a retinal electronic prosthesis.

摘要: Hundreds of thousands around the world have poor vision or no at all due to inherited retinal degenerations (RDs) like retinitis pigmentosa (RP). Similarly, millions suffer from loss age-related macular degeneration (AMD). In both these allied diseases, primary target for pathology is photoreceptor cells that dysfunction and die. Secondary neurons though are relatively spared. To replace cell function, an electronic prosthetic device can be used such secondary receive a signal simulates external visual image. The composite has miniature video camera mounted on patient's eyeglasses, which captures images passes them microprocessor converts data signal. This signal, in turn, transmitted array electrodes placed surface, transmits patterned remaining viable neurons. These (ganglion, bipolar cells, etc.) begin processing pass it down optic nerve brain final integration into Many groups different countries versions device, including implants implants, latter having epiretinal subretinal placement. furthest along development implant sponsored by Second Sight Medical Products (SSMP). Their first-generation had 16 with human testing Phase 1 clinical trial beginning 2002. second-generation 60+ currently 2/3 trial. Increased numbers planned future device. Testing device's efficacy challenge since patients admitted little vision. Thus, methods must developed accurately reproducibly record small improvements function after implantation. Standard tests as acuity, field, electroretinography, even contrast sensitivity may not adequately capture some aspects improvement relate better quality life (QOL). Because this, now relying more "real-world functional capacity" assesses possible everyday living. new battery been suggested include (1) standard psychophysical testing, (2) performance tasks real-life situations object discrimination, mobility, etc., (3) well-crafted questionnaires assess own feelings usefulness SSMP 16-electrode six subjects severe RP were implanted ongoing, continuing then. First, was evident limited sight restoration slow, learning process takes months become evident. However, light perception restored patients. Moreover, ultimately saw discrete phosphenes could perform simple spatial motion tasks. As mentioned above, ongoing A 250+ drawing board, one over 1000 being planned. Each possibility significantly improving QOL, smaller safer design lasting lifetime patient. From theoretical modeling, estimated approximately give good vision, i.e., face recognition reading ability. reality within 5-10 years now. summary, treatments available severely affected dry AMD. An electrical appears offer hope replacing degenerating dead Devices new, sophisticated designs increasing allow long-term recognition, independent living, general QOL.