Promising gene therapy treatment for blindness

University of Oxford scientists have shown how gene therapy could reverse blindness. Most causes of untreatable blindness occur from the loss of millions of light sensitive photoreceptor cells that line the retina. Even after a patient’s eyesight has been lost, the remaining cells that are not light-sensitive are still intact. Scientists injected a gene into the remaining retinal cells of mice, reprogramming them to become light sensitive.

Samantha de Silva, lead author of the study, said: “There are many blind patients in our clinics and the ability to give them some sight back with a relatively simple genetic procedure is very exciting. Our next step will be to start a clinical trial to assess this in patients.”

The mice were monitored for over a year, maintaining their vision during this time, and were able to recognise objects in their environment, indicating a high level of visual perception. The retinal cells that were injected expressed a light sensitive protein, melanopsin, and were able to send visual signals to the brain. The advantage of this treatment method is it may be easier to administer than an electronic retina.

Inherited eyesight diseases such as retinitis pigmentosa affect around 1 in 4,000 people, causing a slow loss of vision and eventual blindness. Previous work by the researchers revealed that unaffected cells can be stimulated to mimic visual responses and have their vision restored using a small electronic implant.

Robert MacLaren, who led the Research at the Nuffield Laboratory of Ophthalmology in Oxford, said: “The effect of retinitis pigmentosa on families with the disease is devastating and we have spent many years working out new ways to slow the loss of sight and to begin restoring it. This new approach is exciting because by using a human protein that is already present in the eye we reduce the chances of causing an immune response.”