Photodynamic therapy (PDT) was traditionally used for treating exudative “wet” age related macular degeneration. Although this is not used as the first line treatment for “wet” macular degeneration anymore, it is still used to treat some refractory cases of exudative macular degeneration and other retinal diseases for e.g. central serous retinopathy.
Photodynamic therapy is a two step procedure. In the first step, the patient gets an intravenous injection of a special dye known as Visudyne® (verteporfin) through the vein. Visudyne® circulates throughout the body and attaches to the walls of the abnormal blood vessels within the affected area. A laser is then used to shine a light onto the retina and choroid. This “cold” laser is of very low power and activates the Visudyne® drug, which has concentrated within the diseased tissue. This results in closure of the abnormal vessel and stops the fluid and blood from leaking.
After receiving photodynamic therapy, the dye remains within the body for a couple of days. As a result patients are required to avoid sunlight or intense halogen lights for a period of three days until the dye has been completely cleared from the body.