A team of British scientists has opened the way to a potential cure for impaired vision after they discovered how to make cells sensitive to light.

A team of British scientists has opened the way to a potential cure for impaired vision after they discovered how to make cells sensitive to light.

Experiments carried out by researchers at Imperial College London and the University of Manchester revealed that some cells in the eye - other than the rod and cone receptors - can be made sensitive to light.

Vision depends on the ability of rod and cone receptors at the back of the eye - the retina - to process information from light, and then send it to the brain via the optic nerve.

Blindness is often caused by a disease of the retina, and is usually irreversible.

The researchers found that activating a protein called melanopsin made other cells in the retina sensitive to light.

By working on mice - which had been blinded by having their rods and cones destroyed - the scientists discovered that by turning on the gene for melanopsin, other cells in the retina became photosensitive.

Although this is not a cure for blindness, it is hoped that the discovery will lead to prosthetic retinas that will help people with sight disorders to see more clearly. Alternatively, the melanopsin gene could be inserted into diseased retinas.

It is also thought the discovery will help people with depression caused by light deprivation during the winter and also with insomnia.

Professor Ron Douglas of City University in London, said: "Much effort is being put into both retinal transplants and even electronic light-sensitive implants.

"However, both approaches are a long way from being clinically effective and they may never be so.

"The current research suggests another possible line of therapy. The resulting 'vision' may well be little more than black and white light sensitivity, but it would be a start," he said.

Professor Chris Inglehearn, professor of molecular ophthalmology at Leeds University, said: "This is highly significant.

"They are getting at the primary process of what makes a cell sensitive to light."

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