PURPOSE: To identify baseline characteristics that predict vision decline (VD) in patients with chronic central serous chorioretinopathy who have anatomically responded to half-dose photodynamic therapy. METHODS: Patients with chronic central serous chorioretinopathy who underwent half-dose photodynamic therapy once and achieved subretinal fluid resolution were retrospectively reviewed. They were categorized into the VD group and the vision maintenance/improvement group based on visual acuity 6 months posttreatment. Baseline OCT, OCT angiography, fundus autofluorescence, and choroidal vascular hyperpermeability patterns were analyzed to identify predictive factors for the VD group. Predictive models were evaluated using the area under the curve from receiver operating characteristic curves to estimate the likelihood of VD. RESULTS: A total of 63 patients were reviewed, with 14 in VD group and 49 in vision maintenance/improvement group. OCT measurements revealed that VD group had significantly thinner layers from internal limiting membrane (ILM) to external limiting membrane (IE) and from ILM to ellipsoid zone (IEZ) (IE: 79.3 ± 22.2 µm vs. 100.1 ± 20.1 µm, P = 0.002
IEZ: 93.9 ± 23.7 µm vs. 114.5 ± 19.8 µm, P = 0.002). The IE and IEZ cutoff values were 84 µm and 95.5 µm (P = 0.006 and 0.008), respectively. The predictive model's area under the curve was 0.743 for IE alone. The best model, which included IE, age, sex, spherical equivalent, fundus autofluorescence, and choroidal vascular hyperpermeability patterns, achieved an the area under the curve of 0.860. CONCLUSION: Baseline IE and IEZ are significant predictors of VD in patients with chronic central serous chorioretinopathy after half-dose photodynamic therapy, making them useful for identifying high-risk patients and discussing these potential outcomes in advance.