Optogenetics—the use of light to control genetically modified neurons—has rapidly become one of the hottest fields in neuroscience. Optogenetic technology is now in use in hundreds of labs across the globe, helping scientists gain insight into the brain. While the bulk of the research is focused in basic science, a handful of projects published this year point the way toward clinical applications. Researchers at Weill Cornell Medical College, in New York, developed a more accurate prosthetic retina for blind mice that had been genetically engineered to express a light-sensitive protein in certain retinal cells. (Now I See You) Gene therapy might one day make the same possible for humans.