Retinitis pigmentosa — a disease that progressively destroys light-sensing cells on the surface of the retina — is one of the most common causes of blindness in young people, affecting about 1 in 4,000 people worldwide. Though there’s no cure for this genetic disorder, scientists are working hard to find new treatments, and a recent breakthrough offers hope that effective therapy may be in sight.
In what’s hailed as a world first, a team of scientists has used light-sensitive proteins found in green algae to partially restore the vision of a blind man who has suffered from retinitis pigmentosa for more than 40 years. Following the treatment, the patient has been able to locate and identify different objects for the first time in decades.
The study used a novel technique called optogenetics, which involves genetically controlling the ability of nerve cells to respond to light. As such, the scientists injected the patient’s weakest eye with genes that encode for a light-sensitive protein that’s found in glowing algae. The injection caused specific neurons in the eye’s retina to respond to light.
The scientists then used a purpose-built pair of goggles equipped with a camera to record the environment and beam light pulses directly on the retina, with its new array of light-sensitive cells. After several months of visual training, the patient was able to locate, identify and even count objects using his eyesight.
“Adjusting to using the glasses takes time,” said study author José-Alain Sahel, chair of ophthalmology at the University of Pittsburgh. “Initially, the patient didn’t find the glasses very useful, but after a few months, he started to see the white stripes on a crosswalk and after several training sessions was able to recognize other objects, big and small.”
The study marks the first time scientists have used optogenetics to partially restore vision in humans. The team says the technique has the potential to one day also treat other conditions including epilepsy, Parkinson’s, and depression.
Source study: Nature Medicine — Partial recovery of visual function in a blind patient after optogenetic therapy