Gene therapy restores vision after disease

Scientists hope early intervention with the surgical treatment will halt progression of the devastating disorder, choroideremia, before patients are robbed of their sight.

It is the first time gene therapy has successfully been applied to the light-sensitive photoreceptors of the retina, the digital camera at the back of the eye.

Preliminary results from the first six patients taking part in a phase one trial surprised and delighted the Oxford University team.

Although the trial was only designed to test safety and dosages, two men with relatively advanced disease experienced dramatic sight improvements.

The researchers are now planning a larger phase II trial that will focus on the therapy’s effectiveness.

Professor Robert MacLaren, who led the gene therapy operations at Oxford Eye Hospital, said: “We’re absolutely delighted with the results so far.

“It is still too early to know if the gene therapy treatment will last indefinitely, but we can say that the vision improvements have been maintained for as long as we have been following up the patients, which is two years in one case.

“In truth, we did not expect to see such dramatic improvements in visual acuity and so we contacted both patients’ home opticians to get current and historical data on their vision in former years, long before the gene therapy trial started.

“These readings confirmed exactly what we had seen in our study and provided an independent verification,” he added.

The research could pave the way to gene therapy treatments for more common blinding conditions, including age-related macular degeneration and retinitis pigmentosa, another inherited disease.

Choroideremia is caused by a defect in the gene CHM and affects about one person in 50,000 in the UK.