Leading article: Clearer view

Specialists at Moorfields Eye Hospital might not have staged a repeat of the biblical miracle of giving sight to the blind, but in medical terms what they have accomplished is almost as exciting.

Leber's Congenital Amaurosis leads to progressive loss of sight. It is caused by a single fault in a single gene.

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Now, by injecting a solution containing the normal gene into the retina at the back of a sufferer's eye, researchers from Moorfields have managed to improve the patient's sight.

The successful result, the details of which are published today in the New England Journal of Medicine, will give hope to millions affected by eye diseases around the world. Inherited retinal degeneration affects one in 3,000 of the world's population.

Because the scientists were being cautious, this experiment deliberately used a low dose and was tested on a patient suffering from a late stage of Leber's disease. Robin Ali, professor of human molecular genetics at the University College London's Institute of Ophthalmology, argues that "as we move to younger patients with an increased dose, we expect better results".

But this research has wider implications. It establishes more "proof of principle" for gene therapy. It suggests that inserting functioning genes into a patient's body can work in alleviating suffering.

This could open the door to treatment in several other conditions, including blood and immune disorders. Medical science does not work miracles, but who would deny that it can create hope where there was none before?