For many blind or partially sighted people, implants that stimulate healthy nerve cells connected to their retinas could help restore some normal vision. Researchers have been working on such implants since the 1980s but with only limited success. A major hurdle is making an implant that can stay in the eye for years without declining in performance or causing inflammation.
Now researchers with the Boston Retinal Implant Project, which was spun out of MIT, Harvard Medical School, and the Massachusetts Eye and Ear Infirmary in 1988, have developed hardware they say overcomes such issues. The implants have been tested in animals, and the group plans to start human trials by 2010.
In retinal diseases such as acute macular degeneration and retinitis pigmentosa, the light-sensing cells of the retina may no longer work, even though the neurons that carry signals from these cells to the brain are still healthy. The Boston project uses an array of electrodes to stimulate these cells and reproduce a simplified visual image in the subject's brain. A camera mounted on a pair of eyeglasses captures an image, which is rapidly processed by a microcontroller to produce a simplified picture. This is then wirelessly beamed to the implant, which activates 15 electrodes inside the eye. The implant also receives power wirelessly from the microcontroller.
In its current form, the implant can reproduce only a 15-pixel image, but the group is working on a version with around 100 pixels and hopes to get up to 1,000 eventually.
The latest implant has been successfully tested in pigs, whose eyes are comparable in size to our own. It hasn't yet been tested in people, but the research group is confident it will restore enough vision to let people walk around unaided.
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