A 46 year-old man called Miikka spotted a simple spelling mistake. A group of scientists had misspelled his name as Mika. He told them as much, and they responded with delight. Why? It was the clearest evidence yet that Miikka, who had been blind for many years, might be able to see again.

This miracle is thanks to a pioneering chip implanted in his retina. Just as cochlear implants have restored hearing to people once considered deaf, devices like this are being developed that can restore sight to the blind.

Miikka suffers from a particular form of blindness called retinitis pigmentosa, an inherited disease that gradually destroys the light-detecting cells of the retina. As the cells die, a person’s field of