SpuriousLogic writes "After receiving injections of genes that produce color-detecting proteins, two color-blind monkeys have seen red and green for the first time. Except in its extreme forms, color blindness isn't a debilitating condition, but it's a convenient stand-in for other types of blindness that might be treated with gene therapy. The monkey success raises the possibility of reversing those diseases, in a manner that most scientists considered impossible. 'We said it was possible to give an adult monkey with a model of human red-green color blindness the retina of a person with normal color vision. Every single person I talked to said, absolutely not,' said study co-author Jay Neitz, a University of Washington ophthalmologist. 'And almost every unsolved vision defect out there has this component in one way or another, where the ability to translate light into a gene signal is involved.' The full-spectrum supplementation of the squirrel monkeys' sight, described Wednesday in Nature, comes just less than a year after researchers used gene therapy to restore light perception in people afflicted by Leber Congenital Amaurosis, a rare and untreatable form of blindness."