Photodynamic therapy (PDT) is an outpatient procedure used to treat wet ARMD. During this procedure, your doctor will inject verteporfin, a light-sensitive medicine, into your blood. The medicine accumulates in the abnormal blood vessels beneath the macula. Laser light is then directed onto the eye to cause verteporfin to create blood clots and block the abnormal blood vessels. By preventing the growth of abnormal blood vessels under the macula, PTD may control the progression of ARMD and further worsening of vision.