ObjectiveTo compare the fast blood flow density (FBFD) of intermediate choroid between endogenous Cushing syndrome (ECS) patients and healthy control subjects.MethodsThirteen eyes of 7 eligible ECS patients (ECS group) and 13 eyes of 7 gender, age, axial length matched healthy volunteers (control group) were enrolled in this study. For each subject, macular radial scan with swept source optical coherence tomography (SS-OCT) was performed and subfoveal choroidal thickness (SCT) was measured. Then 3.0 mm×3.0 mm macular scan with SS-OCT angiography was performed, and selected blood flow image at intermediate choroid level or 1/2 SCT beneath Bruch membrane. The grayscale images were then binarized for the analysis of FBFD.ResultsThe SCT in ECS group was (394.7±77.7) μm, which was significantly thicker than (332.1±68.1) μm in control group (t=2.923, P=0.008). The FBFD of intermediate choroid in ECS group were (76.35±14.46)%, which were significantly greater than (63.57±13.42)% in control group (t=2.775, P=0.01).ConclusionECS patients had increased FBFD at intermediate choroid level compared with healthy controls.