When researchers infused tens of thousands of new stem cells into the retinas of legally blind people, they didn't expect a breakthrough in the patients' vision. But that's what they got, NPR reports: Ten of 18 subjects experienced significant improvement in their vision. The study was intended only to check whether the process was safe. "We did not expect to help these patients, and they did not expect to be helped," says the study's lead researcher, Steven Schwartz. "I'm astonished that this is working in the way that it is—or seems to be working," he says, emphasizing that the results are only preliminary.
The study's subjects had incurable diseases—macular degeneration and Stargardt macular dystrophy—that cause gradual blindness by killing cells known as retinal pigment epithelial cells. In these cases, "whatever you're looking at is gone—whether it's faces, or reading or food on a plate, or whether something is a step or stripe," says Schwartz. Embryonic stem cells can be turned into any type of human cell, and in this case, researchers made them into the type of cells that had been lost. Patients received infusions of 50,000 to 100,000 of the cells. "In a way, it's a retinal transplant," he notes. Among the success stories were a rancher who's resumed horse riding and a woman who can now hike without help; eight patients could read 15 more letters on an eye chart, the Telegraph reports. But the work faces hurdles, including opposition to the use of stem cells. (A bionic eye recently restored some vision to a man in North Carolina.)