Nov. 17, 1999 (Washington) -- Without taking a formal vote, an advisory panel to the FDA recommended laser therapy with the light-sensitive agent called Visudyne (verteporfin) to treat a particularly aggressive form of macular degeneration that can result in blindness. "The treatment is effective, but the treatment effect is very modest ... it's not penicillin," Donald Fong, MD, chair of the Ophthalmic Drugs Subcommittee, tells WebMD.
In the wet form of age-related macular degeneration (AMD), leaky blood vessels grow across the central portion of the retina, or macula, for unknown reasons and cause scarring. Laser therapy selectively destroys the abnormal blood vessels, leaving the normal vessels and tissue alone. About 200,000 cases occur in the U.S. annually, and the ability of current treatments to preserve useful vision is limited to about 20% of new cases.
Fong says about half of those treated with Visudyne still lost vision, but he termed it "a step in the right direction." Since the drug is under a priority review, it could be available in the spring, pending FDA action. If ultimately approved, Visudyne would be a new approach to treating patients with the wet form of AMD, a small percentage of people who develop AMD.
Trials for Visudyne focused on those who have the 'classical' form of the disease, which is considered the most aggressive. In two studies involving more than 600 patients, researchers compared Visudyne to placebo in patients at least 50 years old with a variety of macular-related lesions.
The treatment involves a 30-minute drug infusion, and then, 15 minutes later, a jolt of laser energy aimed into the eye 'turns on' the Visudyne. The drug then inhibits the growth of abnormal blood vessels, apparently without damaging normal tissue. According to the manufacturer, 15% more of those treated with this therapy either stabilized or showed a small loss of vision at the 12-month follow-up compared with those on placebo.
The improvement could mean the difference between 20/100 and 20/200 vision, according to drug investigator Neil Bressler, MD, ophthalmologist at Johns Hopkins University School of Medicine. This is described as clinically significant for those who have the classic type of AMD.
Among the safety problems associated with Visudyne were severe vision loss in a dozen cases, most of which got better over time, and skin sensitivity to light in patients shortly after treatment. The makers of the drug say they plan to conduct training courses for doctors across the country to apprise them of the risk and how to minimize it.
"We're basically putting this systemically administered photo-toxic drug into the body, and we don't know what the long-term effects of these drugs are," says Fong.
Wiley Chambers, MD, who reviewed the drug for the FDA, says there are concerns about the lack of data on the drug's safety and effectiveness. These studies have been done but haven't yet been fully evaluated. Chambers also said most of the patients need another treatment after three months, thus exposing this elderly population to more potential side effects.
Still, panelist Jack Cioffi, MD, of the Devers Eye Institute in Portland, Ore., says Visudyne could stave off vision loss for 6-18 months. For many patients, this could be important in maintaining vision and, therefore, maintaining independence.
- The wet form of age-related macular degeneration (AMD) develops when leaky blood vessels grow across the central portion of the retina and cause scarring, leading to vision loss.
- An advisory panel to the FDA is recommending approval for the light-sensitive drug Visudyne, which, when used in conjunction with laser surgery, destroys the abnormal vessels while preserving healthy ones.
- The benefit of the drug is modest but effective in preventing loss of vision in some patients.