Polypoidal choroidal vasculopathy: outer retinal and choroidal changes and neovascularization development in the fellow eye

PURPOSE. We investigated the outer retinal, RPE, and choroidal changes and the development of choroidal neovascularization (CNV) in fellow eyes of patients with unilateral polypoidal choroidal vasculopathy or aneurysmal type 1 neovascularization (PCV/AT1). METHODS. In this retrospective observational cohort study, 263 patients with unilateral PCV/ AT1 were enrolled. Fundus photography, enhanced depth imaging optical coherence tomography, and indocyanine green angiography at baseline and follow-up were analyzed. Incidence and risk factors for the development of CNV were analyzed. RESULTS. In fellow eyes of unilateral PCV/AT1 cases, RPE and outer retinal abnormalities were observed in 222 (84%) eyes, and dilated Haller vessels (pachyvessel) were identified in the corresponding abnormality area in 157 (71%) eyes. Follow-up data were available for 233 patients. During a 27.6-month mean follow-up period, 20/233 (9%) eyes had CNV (12 PCV/ AT1 and eight type 1 CNV). In 18 eyes (90%), CNV developed at the RPE or outer retinal abnormality areas accompanied by pachyvessel. A significantly higher risk for CNV was observed if RPE and outer retinal abnormalities were accompanied by pachyvessel (hazard ratio, 9.3; 95% confidence interval, 1.1-75.9, P = 0.037). CONCLUSIONS. RPE and outer retinal abnormalities were common in fellow eyes of patients presenting with unilateral PCV/AT1. CNV developed in fellow eyes of 9% of patients, frequently in the areas with RPE and outer retinal abnormality accompanied by pachyvessel.