In a long-awaited success for gene therapy, a research team from the University of Pennsylvania restored sight to two patients suffering from Leber's Congenital Amaurosis (LCA), a previously untreatable form of blindness. The patients had malfunctioning RPE65 genes, which code for a protein that ensures the photoreceptor cells in the retina work smoothly. The scientists used a harmless virus to shuttle a healthy version of the gene into their eyes. As early as a week after the injection, the patients began showing noticeable signs of improvement as the proteins began to have their intended effect on the patients' few remaining photoreceptor cells.

The improvements lasted well after the study's conclusion three months later. The researchers had initially planned on keeping the results confidential--the trial was only designed to test the procedure's safety--but they were so impressed by the results that they decided to share them with the rest of the world. This image shows, at left, an LCA patient's eye before treatment, with a healthy eye at right for comparison.