PurposeTo investigate the morphological features of choroidal vasculature in patients with erectile dysfunction (ED) by analyzing choroidal thickness using optical coherence tomography.Materials and MethodsWe enrolled 39 patients with ED and 19 controls. ED was defined as an erectile function domain score <26 on the International Index of Erectile Function (IIEF) questionnaire. Small-choroidal-vessel-layer (SCVL) thickness was calculated by subtracting large-choroidal-vessel-layer (which corresponded to Haller's layer) thickness from total choroidal thickness. Choroidal thickness was compared between the ED and control groups.ResultsSCVL thickness was lesser in the ED group than in the control group (control, 69.8±24.3 µm vs. ED, 55.1±19.9 µm; p=0.017). Among patients without diabetes, the ED group showed significantly lesser SCVL thickness than did the control group (control, 77.1±22.7 µm vs. ED, 56.5±20.9 µm; p=0.021). However, among patients with diabetes, choroidal thickness showed no significant intergroup difference. Multiple linear regression analysis revealed that spherical equivalent (standardized coefficient β=0.294; p=0.019) and the IIEF erectile function score (standardized coefficient β=0.315; p=0.012) were significantly associated with SCVL thickness.ConclusionsSCVL thickness, including the choriocapillaris layer and medium-sized choroidal vascular layer, decreased in proportion to ED severity, suggesting that microvascular changes in choroidal vessels may occur before specific ocular diseases in patients with ED.