Choroidal vascularity index: An emerging useful metric for choroidal structure assessment in pachychoroid spectrum disease

AbstractPurpose: To compare choroidal vascularity index (CVI) between eyes with different entities of pachychoroid spectrum diseases (PSD) and a control group.Methods: Eighty‐two eyes of 45 patients with PSD were included in our study. Fifteen eyes had uncomplicated pachychoroid (UCP), 27 eyes had pachychoroid pigment epitheliopathy (PPE), 32 eyes had central serous chorioretinopathy (CSC) and 8 had pachychoroid neovasculopathy (PNV). These eyes were compared to 67 eyes of 34 age‐matched healthy controls. All eyes underwent DRI‐OCT Triton Swept‐Source Optical Coherence Tomography (OCT). B‐scan images were binarized into blood vessels lumen and stroma using ImageJ software. The choroidal vascularity index (CVI) was defined as the ratio of luminal area (LA) to total choroidal area in a subfoveal region of 1500 μm width.Results: Mean CVI in patients with PSD was 64.45 ± 2.74%. A statistically significant difference was found between the PSD patients group and the control group (p < 0.001) with a higher CVI in PSD eyes. Pairwise comparisons revealed statistically significant differences between PPE/PNV groups (p < 0.05), PPE/control groups (p < 0.001), CRSC/control groups (p < 0.05) and CRSC/PPE groups (p = 0.05). The comparison between UCP/control groups, UCP/PPE groups, UCP/CRSC groups, UCP/PNV groups, PNV/control groups and PNV/CRSC groups showed no significant difference.Conclusions: Increased CVI may reflect choroidal vascular structure changes in eyes with PSD. These findings suggest that the CVI could be useful for evaluating choroidal vascular changes in eyes with PSD and predicting a potential progression form PPE to CRSC or PNV.