In the mid-1980s, neuroophthalmologist Joseph Rizzo III was researching retinal transplants to restore blind people's vision. One day, removing a lab animal's retina, a tissue-thin membrane that lines the back of the eyeball's interior, he had an epiphany. "The moment I made the cut, I said to myself, 'What in the hell are you doing?'" Rizzo recounts. He realized he was cutting nerve connections that are actually spared in many forms of blindness. The retina's light-sensing cells die off in retinitis pigmentosa and age-related macular degeneration, which affect millions worldwide; but the nearby neurons that ferry the signals from those cells to the brain remain intact. So Rizzo conceived of a retinal prosthesis -- an implant that would take a wireless signal from a video camera, bypass the light receptors, and stimulate the healthy nerve cells directly to feed the image to the brain. Rizzo, working at the Massachusetts Eye and Ear Infirmary and the Boston VA Medical Center, teamed up with MIT electrical engineer John Wyatt Jr. to pursue the scheme. In 1988, they launched the Boston Retinal Implant Project, which today comprises 27 researchers at eight institutions. The team has already done short-term human tests and hopes to test a permanent prosthesis by 2006. Wyatt and Rizzo recently gave TR contributing editor Erika Jonietz a peek at their progress.

1. Image relay. In a small, windowless workroom jammed with tables and equipment in his MIT lab, Wyatt explains how a real-time image is captured and relayed to the retinal prosthesis. While he talks, a visiting scientist named Shawn Kelly models the system's external parts. The idea: a small, commercial digital video camera (the researchers haven't chosen one yet) would be mounted on a pair of glasses. As the user "looked" about, a transmitter -- now just a coil of wires, attached to a circuit board that will be packaged and worn on a belt -- would send images wirelessly from the camera to the implant in his or her eye. "Here's the transmitter coil," Wyatt says, pointing out two concentric copper rings taped to the earpiece of the glasses. Using radio waves, he says, the inner ring sends the data to the prosthesis, while the outer coil sends it power.