Cori Lok in Nature:
Visual impairment affects some 285 million people worldwide, about 39 million of whom are considered blind, according to a 2010 estimate from the World Health Organization. Roughly 80% of visual impairment is preventable or curable, including operable conditions such as cataracts that account for much of the blindness in the developing world. But retinal-degeneration disorders — including age-related macular degeneration, the leading cause of blindness in the developed world — have no cure.In the past seven years, there has been mounting hope and excitement about the prospect of slowing or even reversing vision loss from retinal disorders. Clinical trials testing gene therapy, cell transplants and retinal prostheses are under way, and many studies — including the trial1, 2 involving Morehouse and Haas — are producing promising results. Biotechnology firms are taking up the challenge, and several have formed to take treatments through clinical testing. But most of the successes so far have been in treating rare congenital disorders, and it is still unclear how many people will ultimately benefit and to what extent vision can be preserved or restored. “There's a growing appreciation of the complexity of the clinical problem,” says Thomas Reh, a neurobiologist working on cell transplants for the eye at the University of Washington in Seattle. It may seem vulnerable and complex, but the eye has features that make it a good testing ground for experimental treatments. Unlike internal organs, surgeons can easily operate on it and peer inside to track how well a therapy is doing. It is also walled off from many damaging inflammatory responses that might derail a cell-transplant or a gene therapy. So the eye is “a good way to dip the toes in the water”, says Stephen Rose, chief research officer at the Foundation Fighting Blindness in Columbia, Maryland, which funds research and consults with drug firms.