Researchers at the Philadelphia Children's Hospital and the University of Philadelphia have reported that three patients who underwent gene therapy have seen a dramatic improvement in their vision. The study results were published in the Science Translational Medicine journal. All three patients are afflicted with Leber's Congenital Amaurosis (LCA) which is a rare inherited disease that is caused by defects in a gene encoding a protein needed for vision. In 2008, 12 people with LCA had vision partially restored after receiving an injection of an engineered virus carrying the gene RPE65 in one eye. Three of the patients received the same treatment in their other eye in a follow up study which resulted in an even greater improvement in their vision. All three of the patients could see better in dim light and two of them were even able to negotiate their way around obstacles. Encouraged by these initial results, researchers look to treat the second eye of the remaining nine patients from the initial study and would like to extend the clinical trial. Much more research is needed to fully understand the benefits of gene therapy techniques and how they can be used effectively to treat more common forms of degenerative eye diseases.