RecruitingPhase 2Drug trialA Study to Evaluate Efficacy and Safety of Light Dose in Subjects With PWB Treated With Hemoporfin PDTThis is a multi-center, randomized, double-blind, vehicle-controlled, and sequential group Phase 2 study. Eligible subjects aged 18 to 75 years old with PWB will receive Hemoporfin PDT or vehicle PDT in 8-week cycles at fixed drug dose (5 mg/kg) and different light fluence.