A Photodynamic Therapy Index for Central Serous Chorioretinopathy to Predict Visual Prognosis Using Pretreatment Factors

•Baseline characteristics were analyzed to predict visual prognosis after photodynamic therapy.•Best corrected visual acuity and each neurosensory retinal layer thickness highly predicted the prognosis.•The highest positive predictive value and negative predictive value were 85% and 98% using the estimated cutoff values, respectively. This study aimed to establish a treatment index based on functional outcomes of photodynamic therapy (PDT) for central serous chorioretinopathy (CSC). A retrospective clinical case-control study. This was a single-institute study. Eighty (80) eyes with CSC, who were treated by PDT and whose subretinal fluid resolves within 6 months were divided into two groups: those with poor visual outcome (PVO) (best-corrected visual acuity [BCVA] ≤ 0.5 6 months post-PDT), and the remaining eyes (better visual outcome [BVO]). The areas under the curve (AUC) and cutoff values from receiver operating characteristic curves were examined. These was used to predict the groups using pretreatment BCVA and the thickness of each retinochoroidal layer. Twenty-one (21) eyes were in the PVO group and 59 eyes in the BVO group were included. The AUCs were 0.959 for BCVA, 0.959 for the thickness from the internal limiting membrane to the external limiting membrane (IET), 0.820 for the thickness from the external limiting membrane to the photoreceptor outer segment layer, 0.715 for the subfoveal retinal thickness, and 0.515 for the subfoveal choroidal thickness. The BCVA and IET cut-off values were 0.267 logMAR and 71.5 µm, respectively. Using the combination of the cutoff values of BCVA and IET, the highest values for the sensitivity, specificity, positive predictive value, and negative predictive value were 95.2%, 94.9%, 85.0%, and 98.0%, respectively. The combination of pre-PDT BCVA and IET in CSC can accurately predict the post-treatment visual prognosis. These values could be used as a treatment index of PDT for CSC.