MONDAY, March 17, 2003 (HealthDayNews) -- A drug commonly used for acne may also help treat an eye disease that robs children of their vision, California researchers report.
The scientists injected Accutane (isotretinoin) daily into mice with a genetic defect similar to that in children with a condition called Stargardt's macular degeneration. The condition leads to the deterioration of the area on the retina responsible for central vision.
The drug successfully suppressed the buildup of toxic pigments believed responsible for progression of the disease, they report in this week's Proceedings of the National Academy of Sciences. But experts caution that no one should use Accutane for this disease before further studies are done.
This would be a treatment, not a cure," says study author Dr. Gabriel Travis, a professor of ophthalmology and biological chemistry at the David Geffen School of Medicine at the University of California, Los Angeles.
His team hopes to now begin clinical trials of Accutane. "I think it's likely the treatment with Accutane will do the same thing in humans," he says.
Accutane has been cause for controversy when it comes to treating humans for acne, however. The medication has been linked to numerous reports of depression and suicide, although no direct medical association has ever been made. The drug's maker has taken the step of revising its labeling to reflect those concerns.
Stargardt's macular degeneration, also known as juvenile macular degeneration, is inherited and affects one in 10,000 people, Travis says. Another form of the disease, age-related macular degeneration, affects older people.
About 25,000 Americans have Stargardt's, according to the National Eye Institute, and the condition usually develops between the ages of 6 and 15, although it can also occur in young adults in their 20s and 30s.
"When you have degeneration of the macular, the central part of your visual field goes," Travis says. "It's terrible. You can't read, see faces, watch TV or drive." The juvenile form, he says, can progress much faster than age-related macular degeneration.
Earlier, researchers had identified the gene that causes Stargardt's and named it ABCR. The gene defect disrupts a protein that flushes out a normal byproduct of vision called all-trans-retinaldehyde from the retina's photoreceptors, which are specialized cells crucial to vision.
"So the all-trans-retinaldehyde builds up," Travis says. "When it builds up, it starts doing some mischief." Toxic pigments called lipofuscin build up in the layer of cells near the retina, threatening the photoreceptor cells and vision.
Travis' group chose Accutane to study because they knew one of its side effects is its ability to indirectly inhibit the formation of all-trans-retinaldehyde, which can adversely affect night vision in patients. "Accutane does not hurt the photoreceptor cells," he adds.
Using knock-out mice, which have a genetic defect similar to that in children with Stargardt's macular degeneration, the researchers gave one group Accutane, another group a placebo and a third group nothing at all.
In the drug-treated group, the accumulation stopped; in the other two groups, it did not. During a one-month period in which the toxic pigment accumulation doubled in the untreated animals, the levels in treated animals remained the same.
"When we gave them the Accutane, there was no further accumulation," Travis says.
The drug arrests or freezes the disease, he adds, but does not affect the daylight vision of the treated animals.
Travis warns that no one should try to take Accutane, a drug available by prescription only, on their own hoping to treat Stargardt's or other forms of the disease.
Another expert calls the new study "a very real step forward toward understanding a difficult disease."
Dr. Michael Marmor, a professor of ophthalmology at Stanford University School of Medicine, does, however, adds a caveat.
"It does not yet translate into treatment or cure, and the UCLA caution that patients should not try to treat themselves is wise," he says.
More information
For more information on Stargardt's Disease, see American Macular Degeneration Foundation. For details on the discovery of the Stargardt's gene, see National Eye Institute.
