ObjectiveTo observe the clinical characteristics and risk factors associated with pachydrusen in eyes affected by central serous chorioretinopathy (CSC). MethodsA retrospective clinical study. From July 2021 to June 2024, 144 cases and 158 eyes of CSC patients diagnosed through ophthalmological examination at Department of Ophthalmology of The First Affiliated Hospital of Zhengzhou University were included. All affected eyes underwent a series of assessments, including refraction, intraocular pressure measurement, fundus color photography, fluorescein fundus angiography (FFA), and swept-source optical coherence tomography (OCT). Additionally, 58 eyes underwent indocyanine green angiography (ICGA). Cross-sectional (en-face) OCT was utilized to observe the colocalization of pachydrusen with areas of dilation of large choroidal vessels and attenuation of the choriocapillaris layer. The device was used for OCT included software for calculating subfoveal choroidal thickness (SFCT). FFA fluorescein leakage was categorized into “ink stain”, “cooking smoke”, and “diffuse point leakage”. Patients were classified into groups of CSC patients complicated by pachydrusen and groups of CSC patients without pachydrusen. Comparisons between the groups were performed using the χ2 test, and factors associated with the presence of pachydrusen were analyzed using logistic regression. ResultsAmong 158 eyes, 72 eyes (45.6%, 72/158) were complicated by pachydrusen. In en-face OCT images, pachydrusen were co-located with dilated outer choroidal vessels in 59 eyes (81.94%, 59/72) and corresponded to choroidal capillary layer blood flow holes in 61 eyes (84.72%, 61/72). Among the 58 eyes that underwent ICGA examination, pachydrusen corresponded to punctate strong fluorescence in 46 eyes (79.31%, 46/58) and were located in areas of choroidal hyperpermeability in 43 eyes (74.14%, 43/58). Compared with the CSC group without pachydrusen, the incidence of choroidal neovascularization, flat irregular pigment epithelial detachment, diffuse punctal leakage and multiple leakage points increased in the CSC group, and the differences were statistically significant (χ2=6.217, 8.455, 5.363, 17.749; P＜0.05). Logistic regression analysis indicated that age [odds ratio (OR)=1.116, 95% confidence interval (CI) 1.060-1.176, P＜0.001], chronic CSC [OR=2.628, 95%CI 1.250-5.526, P=0.011] were independent risk factors for the occurrence of pachydrusen. ConclusionsThe incidence of pachydrusen in eyes with CSC is 45.6%, with age and cCSC identified as independent risk factors for their occurrence. Pachydrusen correspond to dilated choroidal vessels and areas of choroidal hyperpermeability, which may serve as potential risk factors for CSC activity or development.