Effects of photodynamic therapy on the choriocapillaris and retinal pigment epithelium in the irradiated area

Purpose: To evaluate the effect of photodynamic therapy (PDT) on the choriocapillaris and retinal pigment epithelium (RPE) in the irradiated area surrounding choroidal neovascularization (CNV) during 12 months of follow-up. Methods: We reviewed the medical records, and indocyanine green angiography (IA), fluorescein angiography (FA), and fundus photographic findings of 72 eyes (72 patients) with CNV associated with age-related macular degeneration (AMD) or polypoidal choroidal vasculopathy (PCV). Patients were divided into three groups based on the number of PDT sessions. Twelve months after PDT, we evaluated the relationship between the number of sessions and both the presence of hypofluorescence in the late phase of IA and window defects observed on FA in the irradiated areas. Results: Twenty-three patients had one PDT session (group I), 25 had two (group II), and 24 had three or four (group III). IA revealed hypofluorescence indicating a choriocapillaris filling defect within the irradiated area in 11 eyes (48%) in group I, 18 (72%) in group II, and 22 (91%) in group III. The correlation between the number of PDT sessions and hypofluorescence in the irradiated areas was significant. FA showed window defects surrounding CNV in 26%, 52%, and 71% of eyes from groups I, II, and III, respectively. Subretinal hemorrhages had been present in 23 eyes (32%) and exudation in 13 (18%) prior to PDT. Areas without hemorrhages or exudation prior to PDT had a normal appearance within the irradiated area in all 72 eyes. Conclusions: Although the RPE in the irradiated area was preserved, 12 months after PDT, mild choriocapillaris occlusion was detected in the irradiated area in eyes that had undergone multiple PDT sessions.