PurposeThe purpose of the study is to investigate the characteristics of choriocapillaris flow based on the underlying choroidal vasculature in fellow eyes with central serous chorioretinopathy (CSC).MethodsWe included 57 patients with CSC and normal controls. Characteristics of choriocapillaris flow were evaluated using swept-source optical coherence tomography (OCT) angiography. We divided the choroidal layer into the vascular and stromal beds according to the choroid vessels on en-face OCT images. We compared the flow void area and mean vascular density of the choriocapillaris according to the underlying choroidal beds in the CSC and control group.ResultsThe mean vascular density of the choriocapillaris in the CSC group was not different from that of the control group (P = 0.289). The flow void area was more frequently found in the CSC group (59.6%) than in the control group (29.8%, P = 0.002). The presence of the flow void area in the CSC group was associated with greater macular choroidal thickness (P = 0.004). In the CSC group, the mean flow void area and ratio of the choriocapillaris over the vascular bed were larger than those over the stromal bed (all P < 0.001).ConclusionsThe location of the flow void area of the choriocapillaris was associated with the distribution of the underlying choroidal vessels. This suggests that the underlying choroidal vessels may affect choriocapillaris perfusion in pachychoroid eyes.