ObjectiveTo observe the changes of macular structure and choroidal capillary blood flow density in patients with acute central serous chorioretinopathy (CSC).MethodsProspective cross-sectional study. A total of 24 eyes of 24 patients with monocular acute CSC (case group) diagnosed by clinical examination from Shanxi Eye Hospital during January and March 2018 were included in the study. The eyes (24 eyes) and contralateral eyes (24 eyes) of the patients in the case group were set to CSC group and contralateral eye group, respectively. Twenty-one eyes of 21 healthy volunteers with age and gender matching were selected as normal control group. The macular structure of the eyes were observed by OCT and OCT angiography (OCTA), and the blood vessel density of choroidal capillary layer in the circular area of the macular area with a radius of 1 mm was measured. The paired t-test was used to compare the differences in blood flow density in the choroidal capillaries between the three groups.ResultsThe results of OCT showed that the serous neuroepithelial detachment in the macular area was observed in all eyes of the CSC group, with or without RPE detachment being 20 or 4 eyes, respectively. Of the 24 eyes in the contralateral eye group, 13 eyes (54.2%) had thick choroidal RPE lesions (PPE). There was no abnormality in the retina and choroidal structure in the macular area of the normal control group. The results of OCTA showed that the blood flow density of choroidal capillaries in the CSC group, the contralateral eye group and the normal control group were 1.759±0.132, 1.924±0.463, and 1.940±0.033, respectively. Compared with the eyes of the contralateral eye group and the normal control group, the blood flow density of choroidal capillaries in the CSC group was significantly lower (t=6.611, 6.474; P=0.000, 0.000). There was no significant difference in the blood flow density of choroidal capillary layer between the contralateral eye group and the normal control group (t=1.328, P＞0.05). In the contralateral eye group, there was no significant difference in the blood flow density of choroidal capillary layer between PPE eyes and no RPE eyes (t=0.806, P＞0.05).ConclusionsThere is 54.2% of the contralateral eyes in the monocular acute CSC patients with PPE. The choroidal capillary layer blood flow density is lower than that of the contralateral and normal eyes.