A new laser treatment is being developed that could help delay the symptoms of an age-related eye condition, writes CLAIRE O'CONNELL.
IF YOU can read this, then you still have good central vision. Now, imagine that faculty ebbing away, making it all but impossible to read, enjoy television, drive and, eventually, recognise faces.
That’s the scenario faced by millions of people with the eye condition age-related macular degeneration (AMD), which is thought to affect around one in 10 people over the age of 55 in Ireland, and is the main cause of registered blindness worldwide.
Over time, the macula, at the back of the eye, becomes damaged from the cumulative stress of incident light and the breakdown of its protective pigments, and vision becomes impaired.
A new laser treatment is being developed to delay the onset of symptoms by rejuvenating the back of the eye, turning back the clock on years of cumulative damage and helping protect vision into older age.
The trick is to use lasers to stress cells in the retina, kick-starting them into cleaning away accumulated debris from the back of the eye and improving function, says John Marshall, Frost professor of ophthalmology at King’s College London.
Prof Marshall’s work in the 1980s led to the use of laser surgery to correct long- and short-sightedness, and he is now taking a new approach with it.
Firing short-pulse lasers at the central retina stimulates a small number of cells to produce enzymes that help clear out natural waste materials that build up with age in the membrane just behind the light-sensitive cells, says Prof Marshall.
“By mid-life, that membrane is so clogged up with junk that it’s only operating at about 50 per cent of the capacity it was operating at when you were a child,” he explains. “If we use the laser to tweak those [cells], they release enzymes which clean up the membrane and re-establish its useful transport properties.”
Early trials of short-pulse lasers with around 50 patients who have diabetic eye problems have shown the principle works and Prof Marshall now hopes to trial the technique on patients who show symptoms of AMD in one eye. Applying the short-pulse lasers to the other, healthy eye could help delay the onset of symptoms there, he says. “In essence what we are trying to do is rejuvenate the retina.”
If the trials go well, the treatment could be available within a few years, according to Prof Marshall, whose work is funded by the charities Guide Dogs for the Blind and Fight for Sight.
The short-pulse lasers could eventually help address a late form of AMD known as atrophic or “dry” AMD, which affects around 85 per cent of patients with the eye condition.
“It’s literally wear and tear of your central retina, so it’s like a carpet which becomes frayed and disintegrated and you can see right through to the floor,” says Stephen Beatty, a consultant ophthalmic surgeon at Waterford Regional Hospital and the Whitfield Clinic.
And unlike the “wet” form, where blood leaks behind the retina and can be treated with injections if caught in time, there is currently no treatment for the “dry” form of AMD, which is where the short-pulse lasers could come in.
“In people who have had late AMD in one eye, by treating their other eye with this laser therapy, in theory we should be able to rejuvenate the membrane and at the very least delay the onset of that untreatable condition in the other eye.”
Meanwhile, scientists are also investigating other approaches to treat AMD, including stem cells, says Beatty. “Stem-cell research does hold a lot of promise and we will get there with it, but it will be about another six or seven years before it’s done in humans,” he says.