A comparative study of the choroidal vascularity indexes in the fellow eyes of patients with pachychoroid neovasculopathy and central serous chorioretinopathy by binarization method

Purpose To evaluate the choroidal vascularity index (CVI) in the fellow eyes of patients with pachychoroid neovasculopathy (PCN) and central serous chorioretinopathy (CSC). Methods Fifty-eight asymptomatic fellow eyes from 58 patients diagnosed with PCN or CSC and 26 eyes from 26 healthy participants were included. The total choroidal area (CA), luminal area (LA), and stromal area (SA) were measured with ImageJ software and Niblack threshold method. The CVI, which was the proportion of the LA to the CA, was assessed. Results The CA, LA, and SA were widest in the fellow eyes of the CSC group. The differences between the fellow eyes of the CSC group and the control group and the differences between the fellow eyes of the PCN group and the CSC group were significant ( p < 0.001). The CVI of the fellow eyes of the CSC group was significantly higher than the control group (74.93 ± 3.58 vs. 73.38 ± 3.09, p = 0.023). Conclusion The differences in the CA, LA, and SA in particular pachychoroid diseases were evident in the asymptomatic fellow eyes. Pachychoroid diseases are characterized by thick choroid or vessels as a common feature, but they may have different structural choroidal features, which might result in different consequences.