Massachusetts Institute of Technology engineers have designed a retinal implant for people who have lost their vision from retinitis pigmentosa or age-related macular degeneration, two of the leading causes of blindness. The retinal prosthesis would help restore some vision by electrically stimulating the nerve cells that normally carry visual input from the retina to the brain.

The chip would not restore normal vision but could help blind people more easily navigate a room or walk down a sidewalk. Patients who received the implant would wear a pair of glasses with a camera that sends images to a microchip attached to the eyeball. The glasses also contain a coil that wirelessly transmits power to receiving coils surrounding the eyeball. When the microchip receives visual information, it activates electrodes that stimulate nerve cells in the areas of the retina corresponding to the features of the visual scene. The electrodes directly activate optical nerves that carry signals to the brain, bypassing the damaged layers of retina.

The research team recently reported a new prototype that they hope to start testing in blind patients within the next three years, after some safety refinements are made. Once human trials begin and blind patients can offer feedback on what they're seeing, the researchers will learn much more about how to configure the algorithm implemented by the chip to produce useful vision.
References:
1. Douglas Shire, Joseph Rizzo, et al. Development and Implantation of a Minimally Invasive Wireless Subretinal Neurostimulator. IEEE Transactions on Biomedical Engineering, October 2009.