Treatment may save thousands from blindness

Scientists believe they may have found a cure for some forms of age-related blindness. Photo: Michele Mossop

London: Thousands of people suffering from common forms of blindness could have their sight restored by a pioneering treatment. Researchers at Oxford University have discovered that by replacing a missing protein in the retina they can prevent cells from degenerating.

The therapy even improves the sight of those who have already begun to go blind in results that have "surpassed expectations".

Two men who were already at an advanced stage of vision loss have experienced "dramatic improvements" in their sight which, so far, have lasted for two years.

Professor Robert MacLaren, of the Nuffield Laboratory of Ophthalmology at the University of Oxford, said: "We're absolutely delighted with the results so far. In truth, we did not expect to see such dramatic improvements 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."

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The trial was carried out on patients suffering from choroideremia - a rare inherited cause of blindness which affects about one in 50,000 people.

It is caused by a defective gene which fails to produce REP-1 - a protein needed to keep pigment cells in the retina healthy. Without it the cells slowly stop working, switch off and die. The first symptom of the condition is usually poor night vision which can occur in early childhood. Later, the field of vision progressively narrows to a "tunnel" until only a small central slit remains.

The scientists found that the protein could be replaced in the eye by inserting it into the DNA of a harmless virus which can be injected into cells beneath the retina. As the virus "infects" these retinal cells the missing protein is restored.

"The purpose of our trial is to put this missing protein back into the retinal cells and prevent further degeneration," said Professor MacLaren.

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Treatment may save thousands from blindness