Sahel et al, Nature Medicine and StreetLab/Institut de la Vision A man who is blind has had glimmers of vision restored thanks to a high-tech treatment using optogenetics, which involves genetically altering nerve cells so they respond to light. French firm GenSight Biologics has published results showing that the first recipient of its treatment can recognise different objects in lab tests. “It’s exciting to see the first publication on human optogenetics,” says Ed Boyden at the Massachusetts Institute of Technology in Boston, a co-inventor of optogenetics. Advertisement Optogenetics has become a widely used lab tool, because it allows precision control over brain cells by altering them so they fire in response to light. It has led to many discoveries about the brain when used in animals – but is thought to have limited medical potential for treating brain disorders in people, because getting light inside the head requires implanting a fibre optic cable.