A revolutionary lens 'on hinges' is being implanted into British cataract patients in the hope it will give them near-perfect vision.

Doctors have begun to insert the tiny device into patients' eyes to find out whether it will give them close up and distant vision.

Cataracts - where the lens in the eye clouds over - are normally treated by fitting artificial lenses. But most patients will need reading glasses because they cannot focus on objects close to them.

The new device could banish that problem. The 9mm lens has four tiny hinges, which allow it to move with the eye as the patient focuses.

Surgeons hope the technique might apply particularly to younger people who work on computers and may suffer from cataracts as a result of accidents or because they have become diabetic.

It might also provide a real improvement for the elderly, for whom cataracts are the bane of advancing years. Chelsea pensioner Ralph Dickinson had the new lens inserted into one eye. One month on he can read again.

Dickinson was one of the first to take part in a study at Guy's and St Thomas's Hospital NHS Trust in south London, which is comparing the traditional lenses with the new type.

Once the cataracts have been removed by ultrasound, the lens, with its four tiny hinges, is placed folded up inside the eye's capsular bag - the transparent membrane surrounding the lens. The hinges are unfurled, and the bag stretches to grow over them. This allows the lens to move with the eye, and because of this, the patient can focus on near and far objects.

Researcher Catherine Heatley said: 'We've treated around 16 patients so far, and of the six or seven we've followed up, all have excellent long-distance vision, and most have better near vision.'

Around 250,000 people a year have cataract treatment on the NHS. The new lenses are expensive, but if they are superior, prices may fall as they become popular.