MS drug combats blindness

A drug developed to treat multiple sclerosis may prove to be an effective treatment for one of the most common causes of blindness.

A team from the Weizmann Institute of Science in Israel used the drug to block loss of eyesight in animals with a disease resembling the human condition glaucoma.

The finding suggests that the drug, Copaxone, may also stop, or at least slow down, the loss of eyesight in people who have a chronic form of the disease.

The majority of patients with chronic glaucoma have increased pressure inside the eye due to defective drainage of the transparent fluid that bathes the eye and nourishes its outer cells.

The increase in this intraocular pressure (IOP) damages the optic nerve, causing it to degenerate and often leading to loss of eyesight.

For many years, the search for improved glaucoma therapies focused on correcting the eye's drainage system to reduce IOP.

Eventually, however, it became clear that reducing the pressure was not enough to halt the ongoing degeneration of the optic nerve and did not eliminate the risk of blindness.

Secondary damage

Professor Michal Schwartz, from the Weizmann Institute, discovered that the initial damage to the nerve triggers the release of chemicals that cause further damage.

These chemicals play an important role in keeping the eye healthy, but when the optic nerve starts to degenerate they are released in much higher, toxic quantities.

One of these chemicals is the neurotransmitter glutamate, which spills from damaged nerve cells and adversely affects healthy neighbouring cells.

However, Professor Schwartz and her team found that Copaxone was apparently able to shield the nerve from the toxic effects of glutamate.

In rats immunised with Copaxone only about 4% of nerve cells died in the glaucoma-affected eye, compared with 28% in rats that were not immunised.

Human trials expected soon

Trials of the drug in human patients with glaucoma are expected to begin soon.

Keith Barton, a consultant ophthalmologist in the glaucoma service at Moorfields Eye Hospital in London, said the study sounded "very exciting".

He told BBC News Online: "At the moment there is only one type of treatment for glaucoma and that is to reduce the pressure in the eye.

"We know that eye pressure is an important factor in glaucoma, but not the only one so any other effective approach would be welcome."

However, Mr. Barton warned that the research was at a very early stage and is was often difficult to draw conclusions on the back of studies on rats.

Mr Barton estimated that around 7% of glaucoma patients do not respond to current treatments.

The research was published in the Proceedings of the National Academy of Sciences USA.

Source: BBC News