For years, they had been losing their central vision—what allows people to see letters, faces, and details clearly. The light-receiving cells in their eyes had been deteriorating, gradually blurring their sight.But after receiving an experimental eye implant as part of a clinical trial, some study participants can now see well enough to read from a book, play cards, and fill in a crossword puzzle despite being legally blind. Science Corporation, the California-based brain-computer interface comp...