Hamburg - Sensitivity to light, a steady decline in eyesight or blurred vision can all indicate the formation of a cataract.

Cataracts, a thickening of the eye's lens, impairs vision and can occur at any stage of a person's life, though they are more common among the elderly.

"There is no guaranteed, medical therapy," says Gisbert Richard, director of the University Eye Clinic in the Eppendorf section of Hamburg. "The only possible treatment is microsurgery to remove the thickened lens is removed and replace it with an artificial lens."

Across Germany, 500,000 such operations are conducted every year. "The procedure is extremely successful and very safe. Centres like ours have a complications rate of less than 1 per cent," said Richard. Of course, the likelihood of complications increases the longer one waits before having the procedure done.

Vision loss clearly reduces quality of life. Nonetheless, every sufferer has to decide when the problem has progressed to a point where surgery seems like a viable option.

"As a rule of thumb, we say that when vision quality drops to 50 or 60 per cent, then surgery is recommended," says Georg Eckert, a spokesman for the German Professional Association of Eye Doctors.

Outpatient treatment is standard nowadays. Normally, patients are only admitted for the procedure, if they suffer from other health problems or when observation is required after the surgery. The procedure is usually performed under local anaesthetic, which blocks pain and prevents the eye from moving too much.

"The inner eye is accessed through a precise incision of only a few millimetres in the cornea or the dermis," explains Richard. The entire lens is removed through the opening, leaving behind the lens capsule. An artificial lens is then injected into the empty capsule.

Artificial lenses are made of materials such as silicon and measure five to seven millimetres. They weigh less than one gram. During surgery, they are folded and injected into the eye, where they unfold of their own accord. Elastic hooks on the edge of the artificial lens ensure that they stay in place.

There are two categories of artificial lens.

"In about 90 per cent of cases, a monofocal lens, which is set to one focal distance, is inserted," says Ingolf Duerr, who works with a German association focused on cataract care.

The monofocal lens means that the eye can no longer change focus between nearby and distant objects. People, who receive this kind of lens, should decide whether they want to be far-sighted and wear spectacles..

"Most people choose a range that allows them to see into the distance."

Recent research into lenses found that the eye can focus on a variety of distances: the multifocal intraocular lens. If it lives up to its promises, the new lens can promise people a life without spectacles.

"The problem here is not the technology or the lens, but getting used to it," says Duerr, adding, "This kind of lens works like multiple-focus spectacles. Not every patient can get used to that." And, unlike spectacles, a patient cannot simply try them out.

The operation lasts about 15 minutes. The eye is then covered with gauze, which can be removed the following day. "Usually, antibiotic and anti-inflammatory eye drops are used for about two weeks afterwards. Then, the second eye can start seeing," says Richard.

Four to six weeks later, a test for corrective spectacles can be carried out. Temporary spectacles can be worn during the intervening period. In some cases where blurring occurs after the operation, an outpatient, pain-free laser treatment is sometimes required to stop this condition. (dpa)