Photodynamic therapy (PDT) uses a light-activated dye (Verteporfin) and a special non-thermal laser. The entire process takes about 20 minutes and is painless. It was originally developed as a treatment for age-related macular degeneration, and is still useful for a sub-type of this disease known as polypoidal vasculopathy. However, it is more commonly used now to treat central serous retinopathy.
The Verteporfin dye is injected via an intravenous infusion into the arm and selectively accumulates in abnormal blood vessels. Shining a non-burning laser into the eye activates the drug, producing free radicals, selectively damaging the abnormal blood vessels. Importantly, because the laser is non-burning, the overlying retina is not destroyed. Depending on the individual’s response to treatment and the disease being treated, the treatment may need to be repeated after several months.
Verteporfin causes light sensitivity up to 48 hours after injection and bright sunlight can cause a serious photosensitive reaction. Patients are advised to wear dark sunglasses and stay indoors and away from direct sunlight for 48 hours. Normal, low-level indoor light is O.K. Other side effects include decreased vision (if some of the normal blood vessels are accidentally shut down as well), a mild headache, dizziness and a drop in blood pressure.