This is a randomized, placebo-controlled, double masked, multicenter, Phase III study. Patients will be stratified by study center and randomized to Visudyne therapy or placebo in a 2:1 ratio, respectively. Patients will receive either a single intravenous dose of Visudyne or placebo followed 15 minutes after the start of the infusion by light application. Follow-up visits will occur every three months (+/- 2 weeks) for the duration of the study. Re-treatment may be administered every three months (through the Month 21 visit) if evidence of CNV leakage is detected by fluorescein angiography (as judged by the Investigator).