"For more than three decades, eye doctors have been employing this treatment because they thought it might work," said principal investigator Dr. Stuart Fine, chair of the University of Pennsylvania Department of Ophthalmology. "Here we have a definitive study ... this should put an end to that treatment."

The study, funded by the National Eye Institute, will be published in the November issue of the journal Ophthalmology.

Fine and colleagues looked at 1,052 patients who were enrolled in 22 clinical centers from 1999 to 2001. The participants, mostly white females at an average age of 71, had at least 20/40 vision in both eyes.

Their eyes also had at least 10 or more large drusen, which are bits of yellow deposits that accumulate under the retina. Presence of drusen often signals the onset of AMD. One eye of each participant was randomly assigned to treatment, and the other was observed without treatment.

The eyes assigned to intervention were given laser treatment at the beginning of the trial, and if needed, again at 12 months. The laser procedure differs from the laser treatment popular for correcting vision.

After five years of follow-up, the researchers found both the intervention group and control group had the same amount of vision loss, which they judged by a person's ability to read lines of text.

Of the treated eyes, 188, or 20.5 percent, had visual acuity scores three lines worse than their initial visit, as did 188 of the observed eyes.

Since the study was a randomized trial, considered the strongest type of experiment, the findings are powerful evidence. However, it's unknown whether the results apply to people who differ from those in the study -- for example, those at lower risk for AMD.

AMD, an incurable disease which affects more than 10 million Americans, occurs when a piece of the retina, called the macula, detoriates. The macula focuses the central vision, as well as enables people to recognize faces, colors and details.

Prior to the CAPT study, it was unknown whether a drop in drusen would also slow the progression of AMD. However, the treatment did confirm previous research that laser treatments can eliminate drusen in treated eyes. Doctors do not understand how lasers get rid of drusen, although some theorize the treatment promotes inflammation in the eye, and the inflammatory cells mop up the drusen.

The participants experienced no side effects to the laser treatment. Some research had suggested laser treatment could accelerate blood vessel growth in the eyes.

Now that laser treatment is deemed a dead end, researchers will have to turn elsewhere for clues.

"I was disappointed, because I was hoping this treatment technology would be a breakthrough," said Dr. Lee Jampol, chairman of ophthalmology at the Fineburg School of Medicine at Northwestern University in Chicago. "CAPT was a promising idea."

Vitamins and supplements might be a worthy avenue of exploration. In 2001, another study by the National Eye Institute, AREDS, showed antioxidant vitamins, especially beta carotene, reduced the chance a person at high-risk for AMD would progress from early to advanced forms of the disease by 20 to 25 percent.

The institute is launching a sequel study, called AREDS II, which will investigate whether lutein -- an antioxidant found in green leafy vegetables -- and omega-3 fatty acids can also prevent the disease, Fine said.

More than 80 percent of the CAPT trial participants took vitamins and/or zinc supplements.

Alcon is also in the midst of a clinical trial to see if a drug, anecortave acetate, works against AMD. The drug slows or halts the growth of new blood vessels that may damage the eye.

Likewise, scientists are learning what causes macular degeneration. Early evidence suggests both genetics and variations of how the body responds to inflammation are at play. Research at the cellular level will certainly lead to more treatments, Jambol said.

Dr. Travis Meredith, a professor and chair of ophthalmology at the University of North Carolina Chapel Hill, said prevention of AMD is a "critical mission" for ophthamologists.

Related Links
University of Pennsylvania Department of Ophthalmology
Hospital and Medical News at InternDaily.com

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