Verteporfin is the generic name of the drug sold as Visudyne, and it belongs to a family of compounds that stay inactive until light of a particular colour reaches them. Visudyne therapy is a two-stage process that requires both the injected drug and nonthermal red light, and once the drug is activated in the presence of oxygen it generates highly reactive, short-lived molecules that damage the lining of the abnormal vessels and cause them to close. Because the drug circulates through your whole body before it is activated, your skin and eyes stay light-sensitive for several days afterwards.
Visudyne has a narrow approved use. It is indicated for the treatment of patients with predominantly classic subfoveal choroidal neovascularization caused by age-related macular degeneration, pathologic myopia, or presumed ocular histoplasmosis, and it was first approved in the United States in 2000. Choroidal neovascularization means abnormal new blood vessels growing beneath the retina, subfoveal means they sit under the centre of your central vision, and predominantly classic describes how they look on a dye test. The label also states that there is insufficient evidence to use Visudyne for predominantly occult lesions.
Doctors may legally use an approved drug outside its labeled indication when the evidence and the patient's situation support it, and this is common with Visudyne. The most frequent example is central serous chorioretinopathy, a condition where fluid collects under the retina. Photodynamic therapy for chronic central serous chorioretinopathy is an off-label option, usually given at a reduced dose of 3 mg per square metre rather than the labeled 6 mg. Reduced-dose, reduced-intensity and shortened-exposure variants are all used off-label. If your treatment is off-label, your specialist should tell you so directly.
