Gene therapy is being used to help restore eyesight to people who are partially blind.
Researchers at Oxford University say their new technique, to help people with eye problems, is working.
People with the disease choroideremia slowly lose their eyesight when cells in the part of the eye used to detect light, called the retina, slowly dies.
Surgeons say the therapy could in future be used to treat the most common forms of blindness.
The new experimental treatment lifts the retina and injects DNA into the area behind it, to protect the cells which are still alive.
In the trial the technique has stopped patients' eyesight becoming worse and for some made it better than before.