Photodynamic Therapy for AMD

Photodynamic therapy is an outpatient procedure involving the use of a special light-activated drug. The inactive form of the drug is usually injected into a vein in the arm, where it travels to and accumulates in abnormal blood vessels under the center of the macula. A special low-intensity laser light targeted at the retina activates the drug only in the affected area, damaging the abnormal blood vessels under the retina and leaving normal blood vessels intact. The benefit of PDT is that it inhibits abnormal blood vessel leakage associated with wet macular degeneration without damaging the retina. 

PDT therapy is indicated for the treatment of abnormal new blood vessels under the center of the macula associated with age-related macular degeneration. These blood vessels must be predominantly well-defined on fluorescein angiographic photographs. PDT therapy is not effective for the treatment of the dry form of AMD, caused by aging and thinning of the tissues of the macula. 

Photodynamic therapy may preserve and, in some cases, improve vision. Repeat treatments are usually needed for optimum results. Photodynamic therapy may be used to treat some patients with the wet form of AMD with fewer visual side effects than other treatments. 

If the abnormal new blood vessels are not under the center of the macula, they may be treated with thermal laser surgery, using a focused beam of high-intensity light to seal the abnormal blood vessels. A small, permanent blind spot is left at the point of laser contact. 

Patients who are treated with PDT will become temporarily sensitive to bright light (photosensitive). Care should be taken to avoid exposure of skin or eyes to direct sunlight or bright indoor light for 5 days. Patients who go outdoors in daylight during the first 5 days after treatment must protect all parts of their skin and their eyes by wearing sunglasses and protective clothing. UV sunscreens are not effective in protecting against photosensitivity reactions.

While photodynamic therapy may preserve and, in some cases, improve vision for many people, PDT may not stop vision loss in all patients. The abnormal blood vessels may regrow or begin to leak again. Every three months, a repeat examination including a fluorescein angiogram (the dye test) is required. Multiple PDT treatments may be necessary.