ObjectiveTo quantitatively analyze the changes of choroidal capillaries in chronic central serous chorioretinopathy (CCSC) before and after half-dose photodynamic therapy (PDT).MethodsA retrospective cohort study. Nineteen patients (21 eyes) with CCSC were enrolled in this study from November 2017 to September 2018 in People’s Hospital of Wuhan University. Among them, there were 14 males (15 eyes) and 5 females (6 eyes), with diseases course over than 6 months. All patients underwent half-dose PDT. Twenty normal subjects (40 eyes) matched with age and sex in CCSC group were taken as controls. The subfoveal choroidal thickness (SFCT) was measured by Heidelberg depth enhanced imaging-OCT before and after PDT treatment in CCSC patients and in normal subjects. Spectral-domain OCT (Retina map) and Angio-OCT angiography (3 mm×3 mm) were arranged for all subjects at the same time. Macular fovea retinal thickness (CMT) was recorded under OCT-Retina map mode, and Angio-OCT 3 mm×3 mm choroidal capillary images were binarized using Image J software, and calculating the area ratio of low pixel area as flow signal void (FSV). BCVA, spectral-domain OCT and Angio-OCT were performed 1 week and 1, 3 months after PDT with the same equipment and methods before PDT. The changes of CMT, SFCT, FSV and BCVA in CCSC patients before and after PDT treatment were compared. Pearson correlation analysis was used to analyze the correlation between FSV and SFCT, age.ResultsThe average CMT, SFCT and FSV in CCSC patients increased significantly compared with the controls (P＜0.05). The average SFCT and FSV in CCSC patients 3 months after treatment were higher and the average CMT decreased compared with the controls (P=0.000, 0.000, 0.000). Comparison before and after PDT in CCSC patients: there were significant differences in average CMT, SFCT and FSV before and after PDT (P=0.000, 0.000, 0.000). Post Hoc multiple comparisons showed that the average CMT (P=0.000, 0.000, 0.000, 0.000, 0.000) and FSV (P=0.010, 0.000, 0.000, 0.001, 0.000) decreased significantly in all time points except for 1 month and 3 months after treatment, so as the average FSV (P=0.788, 0.702). The average SFCT decreased 1 month and 3 months after treatment compared with the baseline (P=0.024, 0.008), and there was no significant difference between before treatment and 1 week after treatment (P=0.162), and between 1 month and 3 months after treatment (P=0.687). The correlation analysis showed that there was no correlation between FSV and age in CCSC patients (r=0.052, P=0.822), but there was a correlation between FSV and age in controls (r=0.716, P=0.000).ConclusionQuantitative analysis of OCTA showes the degree of choriocapillary ischemia in the form of FSV in CCSC patients decreased after PDT treatment, however, which is still higher than normal controls.