October 14, 1999
"I generally tell my patients who will benefit from this treatment that about one-third of them will still lose vision, but without it, two-thirds will lose vision. Put that way, most want it." -- Neil M. Bressler, M.D.
A combined treatment of a light-sensitive medication and a laser light beamed into the eye appears to reduce the risk of vision loss in some patients with age-related macular degeneration (AMD), according to a Johns Hopkins-led study of more than 600 patients at 22 medical centers in North America and Europe.
The treatment, called photodynamic therapy, reduced the risk of vision loss in selected patients with an aggressive "wet" form of macular degeneration -- cases where abnormal leaky blood vessels and scar tissue grow across the center of the retina or light-sensitive part of the eye. Photodynamic therapy reduced the risk of vision loss in 67 percent of these patients. Of those who received a placebo, only 39 percent maintained vision.
Results of the study are published in the October issue of the journal Archives of Ophthalmology. Photodynamic therapy has been submitted to the U.S. Food and Drug Administration for approval.
Photodynamic therapy works like a smart missile, attempting to selectively destroy the abnormal blood vessels caused by AMD while leaving normal retinal vessels and tissue alone. First, a light-sensitive medication called verteporfin is injected in an arm vein over a 10-minute period. During the next five minutes, the drug is picked up by molecules in the blood called lipoproteins -- proteins that combine with fats and that are prevalent in the abnormal blood vessels. Then, doctors shine a beam of red laser light into the eye for about a minute and a half. The laser is too weak by itself to have any effect on the retina, but it activates the drug, which produces a toxic, reactive form of oxygen that can damage the diseased tissue and blood vessels.
"This is not a cure, nor does it apply to those who already have lost significant vision, but it does appear to be effective in preventing further vision loss for some patients who have recently developed the wet form," says Neil M. Bressler, M.D., chairman of the clinical centers for the trial and a professor of ophthalmology at Hopkins. "I generally tell my patients who will benefit from this treatment that about one-third of them will still lose vision, but without it, two-thirds will lose vision. Put that way, most want it."
Wet AMD represents an estimated 15 percent of all AMD cases, yet accounts for approximately 90 percent of the severe vision loss associated with the disease. More than a million people in North America have at least the early stage of disease, and up to 200,000 new cases of the wet form are diagnosed in the United States each year.
During the double-blind study, 609 patients (including 35 at Hopkins) were randomly assigned to verteporfin or placebo treatment. Patients had follow-up exams every three months for up to two years; they received additional treatments during the follow-up exams if the abnormal lesions suggested further growth or vision loss.
The study was sponsored by QLT PhotoTherapeutics Inc., Vancouver, British Columbia; and CIBA Vision Corp., Duluth, Ga., co-developers of photodynamic therapy. Bressler is a paid consultant to QLT PhotoTherapeutics Inc. The terms of this arrangement are being managed by The Johns Hopkins University in accordance with its conflict of interest policies.
Patients seeking more information on photodynamic therapy can call 1-800-821-2450 or check http://www.visudyne.com -- a Web site set up by the companies that investigated the therapy.
Wilmer Eye Institute at Johns Hopkins -- http://www.wilmer.jhu.edu/
Visudyne (photodynamic therapy) treatment -- http://www.visudyne.com/
QLT PhotoTherapeutics Inc. -- http://www.qlt-pdt.com/
CIBA Vision Corp. -- http://www.cibavision.com/
Note: The journal article will be available on the Internet at http://www.archophthalmol.com.