Photodynamic therapy for polypoidal choroidal vasculopathy: Vaso-occlusive effect on the branching vascular network and origin of recurrence

Purpose: To determine whether photodynamic therapy (PDT) has a vaso-occlusive effect on the branching vascular network in polypoidal choroidal vasculopathy (PCV) and whether PDT can prevent future recurrence. Methods: We analyzed pre- and post-PDT indocyanine green angiography (ICGA) results of 27 patients (27 eyes) who were diagnosed with PCV and who had shown clinical improvement accompanied by occlusion of polypoidal lesions after PDT. We also investigated the recurrent events in these patients and the origin of the recurrences. Results: The branching vascular network persisted, at least in part, in 20 (87%) of 23 eyes undergoing one PDT session and in two (50%) of four eyes undergoing two PDT sessions. In the remaining five eyes, we could not determine definitively whether the branching vessels were occluded completely. Recurrent serous changes occurred in nine eyes (33%) 14-48 months after the last PDT. ICGA revealed that these changes were caused by new polypoidal lesions that originated from further-grown branches of the persistent branching vascular network. Diffuse leakage from undetermined sources seemed to coexist in two eyes. Conclusions: PDT cannot induce complete occlusion of the branching vascular network. PDT does not prevent future recurrence, because new active polypoidal lesions may develop from the persistent branching vessels in the network.