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The pump that can save your eyesight

British technology is powering a new therapy for treating the most common cause of sight loss, a condition that affects more than half a million people in the UK.

Results from the first trials show the blood-filtering technique can improve vision, with patients who had the therapy more likely to pass vision tests for driving than people with the same condition who were given a dummy treatment.

After 12 months of the treatment, those receiving the therapy for agerelated macular degeneration (AMD) were seeing an average of three lines more on the eye chart than patients in the other group.

Larger clinical trials are now under way in Europe and the U.S. to see whether the same kind of results can be achieved with greater numbers of patients.

AMD is the most common cause of blindness in people over the age of 50.

The macula lutea is in the central area of the retina, the light-sensitive layer of tissue at the back of the eye. As you read, light is focused on to the macula lutea, where millions of cells change the light into nerve signals that tell the brain what you are seeing.

This central vision is the key to being able to read, drive, and other activities that need fine, sharp, straightahead vision.

In the so-called dry form of AMD, which makes up nine out of ten cases, the cells of the macula lutea become damaged and the images the patients see start to fade, like colours in an old picture.

As the light-sensitive cells in the macula lutea die, central vision may become blurred or distorted in the early stages, with, for example, straight lines appearing wavy as the brain tries to make up for the absence of an image. As the condition progresses, central vision may be lost.

The cause of the condition is not known and there is no cure. Women may be more at risk than men. Smokers, people with a family history of AMD and those with a high level of cholesterol are thought to be at higher risk.

In the new treatment now on trial, called rheopheresis, the patient's blood is filtered to take out larger molecules that researchers believe could interfere with circulation.

Details of the treatment were given at the conference of the German Ophthalmic Surgeons Association.

Delegates were told that the purification treatment gets rid of compounds in blood plasma such as fibrinogen and cholesterol that may contribute to the development of AMD.

The theory behind the treatment is that the removal of these larger compounds improves blood flow and unclogs veins in the retina, allowing cells to recuperate.

During the two-hour treatment, two intravenous lines, one to each arm, take out blood and

How the pump works

The first filter separates the plasma from the whole blood and sends the plasma to the second filter, which sieves out the large molecules.

It's a painless procedure, with no anaesthetic involved, and patients get only their own blood back.

Results of the first trials, with around 80 patients in Germany and the U.S., have shown what are described as significant improvements. A trial is now underway in different places in the U.S., and a second has been launched in Europe.

OccuLogix, the biomedical company behind the development, says interim results from the trial in the U.S. show that after 12 months, the patients who had the treatment were seeing an average of three lines more of an eye chart than those in the placebo group.

'In addition, of those cases not initially able to pass vision tests for driving, approximately six in ten treated cases were able to qualify for their driving vision exams after treatment, compared with only one in ten of the placebo cases,' says a spokesman.

Steve Clarke, technical director of Kimal - the company based in Uxbridge, Middlesex, which designed and makes the pumps at the centre of the treatment - says doctors discovered the idea of using the technology for AMD by chance.

'They were using a type of filtering system to tackle cholesterol and they noticed that the vision of patients with AMD seemed to be improving, too,' he says.

'The results so far show a remarkable impact on vision.

'One of the problems with this kind of condition is that it is difficult to quantify the improvements with the various markers that doctors use. But the patient knows when there have been improvements.

'He knows, for instance, when he can see his golf ball when he couldn't see before, whatever the figures say.'

He and his company have been talking about the technology to doctors in the UK, who are awaiting the trial results. 'We are crying out for a better set of treatments for this disorder, but we have not seen any results yet,' says Andrew Webster, consultant at Moorfields Eye Hospital in London and lecturer at the Institute of Ophthalmology. 'If it works, we will all be delighted, but we do need to wait.'

OccuLogix says the results have been so good that it has permission to let those patients who were getting the dummy treatment have the real therapy.

If all goes well, the treatment could become available within a year.