JULY 7, 2009--Research conducted by Professor John Marshall of King's College (London, England) sponsored by The Guide Dogs for the Blind Association (Reading, England) has produced a short-pulse laser-based sight-saving treatment that could prevent the onset of age-related macular degeneration (AMD), reportedly the number-one cause of blindness in the UK, and according to the US's National Institutes of health, a leading cause of vision loss in Americans 60 and older. The disease leaves millions of people unable to read, drive or live independently.
While it is not a cure for existing sight loss, there are encouraging signs that it could prevent a generation from developing AMD. People with a family history of the disease could have pre-emptive treatment in their thirties and it could even stop the disease from progressing in existing patients.
Ophthalmologist Marshall, who pioneered laser surgery to correct shortsightedness, said, "It is really exciting news. It won't bring back damaged eyesight but it may prevent AMD, including "dry" AMD for which there is currently no treatment."
AMD is caused by damage to an area about 5mm across at the centre of the retina called the macula, which is responsible for our central vision. The laser technique reinvigorates the Bruch's membrane, a thin layer that lies behind the retina and supplies light-sensitive cells with nutrients while removing waste created as a by-product of the retinal cell renewal process. Over time, the membrane loses the ability to take waste away, allowing deposits to build up.
In a trial involving more than 100 diabetics, Marshall found that using a laser stimulated the membrane, enabling it to once again remove waste from the eye. The non-invasive operation uses laser light that does not damage the eye's light-sensitive cells or cause any dangerous heating.
Marshall will now treat up to 200 people with AMD in one eye as part of a second trial. Such patients usually get the disease in the other eye within three years.
He believes the laser could prevent the better eye losing its sight. "If you can delay the onset by three, four, six, seven or ten years, it's proof of the principle," he said.
"This is exciting news, potentially for millions," said Guide Dogs' Director of External Affairs, Tom Pey. "The science behind this is proven and, although clinical trials are likely to take years, we hope it will be in single figures." He added, "We must stress, thoug,h that the work Prof Marshall carried out is primarily going to be a preventative for those who do not yet show signs of AMD. For those who already are suffering, there is unfortunately unlikely to be major improvements as once the damage is done, as in so many causes of blindness, the effects are irreversible."
Guide Dogs has invested £11m in more than 100 ophthalmic research projects over the last 18 years. Guide dog training started in 1931 in the UK. The Guide Dogs for the Blind Association was founded in 1934.
For more information see yesterday's Times Online article covering the research. And find out more about Prof. John Marshall at the King's College site.