Photograph by Laitr Keiows
A new gene therapy has found success in improving the vision of six patients suffering from choroideremia.
Pioneered by researchers from Oxford University and with the operations performed at the Oxford Eye Hospital, the patients were injected into the back of the eye with a virus that has been modified to carry a working copy of the gene CHM that the patients lack.
The therapy was originally intended to slow or stop the degeneration of the patients’ eyesight and make sure the procedure and virus did not damage the retina, but it actually went further in the patients and drastically improved their vision.
The patients reported being able to see three more lines on the optician’s eye chart, as well as brighter and more vibrant colours “as if someone had switched on the floodlights”.
The results of the trial at six months were reported in the medical journal The Lancet today, and as a result of the success of the first six patients, three more have recently been tested at a higher dose.
Professor Robert MacLaren of the Nuffield Laboratory of Ophthalmology at the University of Oxford, and a consultant surgeon at the Oxford Eye Hospital, led the development of the retinal gene therapy and the first clinical trial, and said of the trials:
“It is still too early to know if the gene therapy treatment will last indefinitely, but we can say that vision improvements have been maintained for as long as we have been following up the patients, which is two years in one case.
We are now trying higher doses of the gene therapy in the next part of the clinical trial to find what level is needed to stop the degeneration.”
Choroideremia is a rare inherited cause of blindness that affects around 300,000 people in Britain and a deterioration in the quality of sight for one in four people over the age of 75, and there is currently no cure. It is found almost exclusively in males as it is caused by defects in the CHM gene on the X chromosome, where pigment cells in the retina slowly stop working and die off. The aim of the gene therapy is to treat sufferers early in their teens to prevent them from going blind.
