Hauswirth cautioned that it will take several years before the experimental treatment can be tested in people.
"This experiment showed us that this kind of therapy has potential to work, but now we need to go back and do very structured and rigorous tests to look for any signs of ill effects from the treatment," Hauswirth said. "And then in the early phase of testing in people, we also will be looking first at whether it causes any problems, rather than actually trying to reverse blindness."
LCA is an autosomal recessive disease, meaning that one copy of a mutated gene must be inherited from each parent to cause symptoms. Such mutations also occur in Briards and other dogs that have been inbred to preserve characteristics of their breed.
"The retina initially looks normal," Hauswirth said. "Over time, however, the retina starts losing part of its structure because there is no visual input. By the time a child is 10 or 15 years old, the light-sensitive photoreceptor cells are usually gone. At that point, putting in this gene isn't going to restore vision. So there almost certainly is going to be a window of treatability for LCA patients -- probably the younger the better."
In their next phase of animal testing, the scientists will try to pinpoint the time of life during which treatment might be effective. "That's such a critical question to deciding what populations in humans might benefit, although there's no guarantee that it will translate exactly to people," Hauswirth said. "No one really knows what dog years versus human years means in the eye."