A prosthetic device that can restore some sight to the blind has been approved by the U.S. Food and Drug Administration. The company that makes the device, Second Sight, based in Sylmar, California, can now market the retinal prosthetic to patients with advanced retinitis pigmentosa, a degenerative eye disease that can cause blindness. This is the first approved treatment for the disease in the United States.
“This enables people who are completely blind to see enough to improve their mobility,” says Mark Humayun, a professor of biomedical engineering at the University of Southern California in Los Angeles who has been developing the device for the past 25 years. “It allows people to make out the sidewalk and stay on it without twisting an ankle, see unexpected obstacles like parked cars, make out a table, see someone coming through a doorway,” he says. Some patients can make out large letters, but the main function of the implant is to give patients enough sight to restore mobility.
The device, called the Argus II, has three main parts: a glasses-mounted video camera; a portable computer; and a chip implanted near the retina. The video camera sends image data to the computer, which is worn on a belt. The processor converts the image data into electrical signals that are beamed to a chip implanted near the retina. The signals are then sent to an array of 60 electrodes that stimulate the retinal cells. These electrodes essentially do the work of the light-sensing cells that have degenerated. So far, the system can’t help patients make out different colors, but it can provide them with enough visual sensation to sense the outlines of things nearby.