ObjectiveTo observe the efficacy of optical coherence tomography angiography (OCTA) guided half-dose photodynamic therapy (PDT) in the treatment of acute central serous chorioretinopathy (CSC). MethodsA prospective randomized controlled trial. A total of 72 patients (72 eyes) with acute CSC in Peking University People's Hospital from April 2019 to April 2020 were included in the study. They were randomly divided into OCTA group (OCTA-guided PDT, 31 eyes of 31 patients) and indocyanine green angiography (ICGA) group (ICGA-guided PDT, 33 eyes of 33 patients). All patients underwent best corrected visual acuity (BCVA), fundus color photography, OCTA and ICGA examinations. International standard visual acuity chart was used for BCVA examination, which was converted into logarithm of the minimum angle of resolution (logMAR) visual acuity. In OCTA group, the hyper-reflective area on en face OCTA image at choriocapillaris level was identified as treating area. In ICGA group, the area of choroidal vascular hyperpermeability on ICGA which was related to the leakage on fundus fluorescein angiography (FFA) was identified as treating area. The area corresponding to the treating area on FFA or ICGA was outlined on the color fundus photograph to guide PDT laser spot. The complete subretinal fluid (SRF) resolution, BCVA, central retinal thickness (CRT) at 1, 3, 6 months and SRF recurrent rate at 3, 6 months were observed. Continuous variables between the two groups were compared by t-test or Wilcoxon rank sum test. The χ2 test was used to compare the categorical variables. ResultsAt 1, 3 and 6 months after treatment, the SRF absorption rate in OCTA group and ICGA group was 74.2% (23/31), 63.6% (21/33), 87.1% (27/31) and 84.8% (28/33), 96.8% (30/31), 91.9% (31/33), respectively. OCTA-guided PDT was demonstrated noninferior to ICGA-guided PDT for complete SRF resolution at 1, 3, 6 months [95% confidence interval (CI) －11.9%-33.1%, P=0.402; 95%CI －14.7%-19.3%, P=0.107; 95%CI －6.3%-16.1%, P=0.226]. There was no significant difference in the recurrence rate of SRF between the two groups at 3 and 6 months after treatment (χ2=0.009, 0.047; P=0.925, 0.828). The difference of CRT was statistically significant at 6 months (t=2.017, P=0.047). There was no significant difference in logMAR BCVA at 1, 3 and 6 months after treatment (t=0.529, 0.762, 1.017; P=0.581, 0.403, 0.243). ConclusionsDuring 6 months follow-up, OCTA-guided PDT was demonstrated noninferior to ICGA-guided PDT for the SRF absorption rate in patients with acute CSC.