RESEARCHERS at Oxford’s John Radcliffe Hospital have made a breakthrough in tackling a cause of progressive blindness.
Six patients have seen improvements in their vision after taking part in the first clinical trial of a gene therapy for a condition called choroideremia.
After the treatment, which involves inserting a gene into the eye, the patients showed improvements in their vision in dim light and two of the six were able to read more lines on the eye chart.
Professor Robert MacLaren, of the Nuffield Laboratory of Ophthalmology at the University of Oxford, and a consultant surgeon at the Oxford Eye Hospital at the JR, led the trial.
He said: “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.”
Prof MacLaren said the readings confirmed exactly what they had seen in their study.
He said: “This has huge implications for anyone with a genetic retinal disease such as age-related macular degeneration or retinitis pigmentosa, because it has, for the first time, shown that gene therapy can be applied safely before the onset of vision loss.”
Choroideremia is a rare inherited cause of blindness that affects around one in 50,000 people.
The first signs tend to be seen in boys in late childhood, with the disease slowly progressing until vision is lost. There is currently no cure.
The therapy is given in one eye to allow comparison with progression of the disease in the other eye.
Barrister Jonathan Wyatt, 65, was the first patient to be treated during the trial.
He said: “My left eye, which had always been the weaker one, was that which was treated as part of this trial.
“Now when I watch a football match on the TV, if I look at the screen with my left eye alone, it is as if someone has switched on the floodlights.”
The clinical trial is funded by the Health Innovation Challenge Fund, a partnership between the Wellcome Trust and the Department of Health.
It has received additional support from the National Institute for Health Research Oxford Biomedical Research Centre and the charity Fight for Sight.
Abingdon resident Annette Hornsby, 48, who was registered blind aged 12, took part in a a ground-breaking “bionic eye” hospital trial in 2012.
A retinal implant was placed in her eye which sends electronic signals to the optic nerve and brain, enabling better sight. But it degraded and was later removed.
She said: “The research they are doing gives people like me a lot of hope. I was told that there was no cure and the future looked very bleak but it gives people hope and that’s a massive thing.”
HOW IT WORKS
- In a healthy eye, retina cells at the back detect light but a faulty gene means these cells begin dying causing partial blindness.
- To stop further degeneration, fluid is injected to lift a layer of the cells. Working copies of the faulty gene are then injected to stop the rest of the cells dying.