An Electrifying Sight

A Wheaton, Ill., startup founded by an ophthalmologist is working on an artificial silicon retina that could restore sight to those suffering from macular degeneration-the leading cause of blindness in people older than 65. The device is a silicon wafer 3 millimeters across covered with photodiodes. With the wafer implanted in the retina, the photodiodes convert light into electrical impulses that travel through the optic nerve to the brain. The photodiodes will be packed so densely that the “resolution will theoretically be as good as normal vision,” says Optobionics founder Alan Chow; Stanford University’s Nanofabrication Center is collaborating on the miniaturization.

The implant has induced retinal activity in animals, but studies with human volunteers are more than a year away. Because the photodiodes are sensitive to infrared as well as visible light, Chow says these first subjects may report some odd sightings, such as beams shooting from a TV remote control.