For 100 million people around the globe who suffer from macular degeneration and other diseases of the retina, life is a steady march from light into darkness. The intricate layers of neurons at the backs of their eyes gradually degrade and lose the ability to snatch photons and translate them into electric signals that are sent to the brain. Vision steadily blurs or narrows, and for some, the world fades to black. Until recently some types of retinal degeneration seemed as inevitable as the wrinkling of skin or the graying of hair—only far more terrifying and debilitating. But recent studies offer hope that eventually the darkness may be lifted. Some scientists are trying to inject signaling molecules into the eye to stimulate light-collecting photoreceptor cells to regrow. Others want to deliver working copies of broken genes into retinal cells, restoring their function. And a number of researchers are taking a fundamentally different, technology-driven approach to fighting blindness. They seek not to fix biology but to replace it, by plugging cameras into people’s eyes.
Scientists have been trying to build visual prostheses since the 1970s. This past spring the effort reached a crucial milestone, when European regulators approved the first commercially available bionic eye. The Argus II, a device made by Second Sight, a company in California, includes a video camera housed in a special pair of glasses. It wirelessly transmits signals from the camera to a 6 pixel by 10 pixel grid of electrodes attached to the back of a subject’s eye. The electrodes stimulate the neurons in the retina, which send secondary signals down the optic nerve to the brain.
