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Age-related macular degeneration (AMD) is a disease that progressively destroys the central portion of the retina (macula). AMD is the most common cause of severe vision loss after age 60. As many as 30-million people throughout the world are thought to suffer from the condition.

There are two types of AMD—the wet type and the milder and more common dry type. Although the wet form of AMD accounts for just 10% to15% of all AMD cases, it is responsible for 90% of severe vision loss associated with the disease.

St. Luke’s Medical Center offers Photodynamic therapy (PDT), a new treatment for the wet form of AMD. In PDT, a light-activated drug called verteporfin (Visudyne) is injected into the patient's bloodstream and preferentially collects in the abnormal blood vessels under the macula. Once this drug is administered, a surgeon aims a low-intensity or "cool" laser at the area of blood vessel growth. The laser activates the drug, which then destroys the leaky blood vessels.

Since the drug is confined within the blood vessel, the laser treatment mainly targets the vessel and does not harm the overlying retinal tissue. PDT offers patients with wet AMD a safer, more effective sight-saving therapy than traditional laser treatment.

By limiting the growth of abnormal blood vessels under the macula, photodynamic therapy may help prevent the progression of wet AMD. However, only 20% to 30% of wet AMD cases can be effectively treated with PDT. It does not restore vision to eyes that have already been damaged, but it may help prevent further damage to the retina and further vision loss.

What should I expect after treatment?
The light-activated medicine (verteporfin) used in PDT makes your skin and eyes more sensitive to light. Therefore, after treatment, avoid direct sunlight for 2 to 5 days; when outdoors, wear special dark sunglasses to protect your eyes. See your St. Luke’s ophthalmologist for a follow-up exam about a month after treatment.

How well does PDT work?
Studies have shown that PDT is effective in reducing the growth of and leakage from abnormal blood vessels under the retina and in reducing the risk of vision loss. How well the treatment works depends on where and how the abnormal blood vessels are growing beneath the retina. For some types of wet AMD, the treatment has no detectable benefit.

The effect of PDT in slowing the progress of AMD is often temporary, and the abnormal blood vessels begin leaking again after about 3 months. Most people need multiple treatments to get the full benefits of the therapy.

What are the risks and benefits of PDT?
PDT has been shown to be effective only for certain types of wet AMD. The treatment may not work for you.

PDT has only recently begun to be widely used, and its effectiveness and long-term consequences are still being studied.

Verteporfin is an expensive medicine, adding to the overall cost of the treatment. However, you must balance this cost against the potential benefit it provides in slowing or reducing the loss of vision from AMD.