Abstract： Objective To evaluate the characteristics of choroidal thickness changes and abnormalities in choroidal circulation in cases of central serous chorioretinopathy (CSC).Methods This was a case control study,we measured the bilateral choroidal thickness in 21 patients with unilateral CSC and 24 eyes of 24 age-and sex-matched normal subjects using enhanced depth imaging optical coherence tonography (EDI-OCT).The choroid was measured from the posterior edge of the retinal pigment epithelium (RPE) to the choroid-scleral junction at 500 μm intervals of a horizontal section from 3 mm temporal to the fovea to 3 mm nasal to the fovea.Paired-samples t-test was conducted to compare mean choroidal thicknesses between symptomatic eyes and fellow eyes of patients.The datum between patients and normal subjects were analyzed by independent-samples t-test.Fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were performed and the digital images were analyzed in CSC patients.Results The 21 CSC patients had a mean age of 45.6 years,and 12 patients (57.1％) were male.The choroid in symptomatic eyes was thickest beneath the fovea (519.0 ± 102.5) μm.It was significantly thicker than that in the fellow eyes (439.3 ± 94.1) μm (t =4.171,P ＜ 0.05).Choroidal thickness in both groups was significantly greater than that in the eyes of age-and sex-matched normal subjects (332.0 ± 67.3) μm (t =7.125,4.441 ;P ＜0.05).Choroidal thickness at each of the other 12 points showed a similar tendency (t =2.544 to 3.819,4.799 to 7.816,2.487 to 5.236;P ＜0.05).ICGA showed a choroidal filling delay (100％),vessels dilation (90.5％),and focal choroidal hyperfluorescence (100％) surrounding leakage from the RPE in symptomatic eyes.Pigment epithelium detachment with abnormal choroidal circulation was observed in 6 fellow eyes.In 4 symptomatic eyes and 11 fellow eyes,ICGA revealed choroidal hyperfluorescence but FFA showed normal appearance.Conclusions CSC seems to be a bilateral eye disease with choroidal focal ischemia followed by vessels congestion and hyperpermeability.EDI OCT is a useful tool for monitoring choroidal thickness changes caused by choroidal vascular hyperpermeability.