Weill Cornell Medical College researchers have built a new type of prosthetic retina that enabled blind mice to see nearly normal images. It could someday be used to restore detailed sight to people who’ve lost their vision to retinal disease.

They used optogenetics, a recently developed technique that infuses neurons with light-sensitive proteins from blue-green algae, causing them to fire when exposed to light. Researchers used mice that were genetically engineered to express one of these proteins, channelrhodopsin, in their ganglion cells. Then, they presented the mice with an image that had been translated into a grid of 6,000 pulsing lights. Each light communicated with a single ganglion cell, and each pulse of light caused its corresponding cell to fire, thus transmitting the encoded image to the brain.

For human adaptation, such a setup would require a pair of high-tech spectacles, embedded in which would be a tiny camera, an encoder chip to translate images from the camera into the retinal code, and a miniature array of thousands of lights. Surgery would no longer be required to implant an electron array deep into the eye, although some form of gene therapy would be required in order for patients to express channelrhodopsin in their retinas.