If ongoing studies in dogs go well, the researchers said, the first human studies could begin in the next three to four years. We have to be careful not to fill people with false expectations or false hopes,'' said Albert Maguire, an ophthalmologist at Penn's Sheie Eye Institute who was involved in the new study. But that said, it's hard not to get very excited about this because it's a very dramatic result. Children with LCA have little or no vision at birth, and what little may be there is lost over time. It occurs when there is a defect in any of several genes that help convert light into electrical signals in the eye.
Parents carrying the defect on one copy of the gene have normal vision.
Mutations in any of a dozen or so other genes also cause LCA, and mutations in scores of others genes cause other forms of retinitis pigmentosa. Previous studies on rats and mice with LCA had achieved temporary restoration of vision with a highly toxic nutritional additive, and longer lasting but only partial restoration with gene therapy. It's difficult to measure visual acuity in dogs. But by all measures, they are still seeing very well nine months after they were treated, with no ill effects. The tests, done in puppies 3 or 4 months old, do not prove that the method will work in children, much less in adults.