Repeatability of Choroidal Vascularity Index Measurements Using Directional Optical Coherence Tomography Images.

PURPOSE To investigate the repeatability of choroidal vascularity index (CVI) measurements in centered and decentered (regarding pupil entry position of the beam) directional subfoveal optical coherence tomography (OCT) scans with (CVI1) and without (CVI2) brightness adjustment. METHODS Thirty-two eyes of 32 healthy volunteers were included in this prospective study. First, the fovea was evaluated by a single horizontal enhanced depth imaging OCT scan in a centered direction. Then, the same subfoveal horizontal line was scanned in a decentered direction. The agreement between CVIs obtained from these centered and decentered directional OCT scans was investigated using Bland-Altman analysis and intra-class correlation coefficient (ICC). RESULTS ICC between centered and decentered CVI1 was 0.71 (95% CI: 0.48 - 0.85, P value <0.001). ICC between centered and decentered CVI2 was 0.73 (95% CI: 0.5- 0.86, P value < 0.001). The mean difference between centered and decentered directional measurements for CVI1 and CVI2 were 0.5 and 0.8, respectively. CONCLUSION There is moderate agreement between CVIs obtained from centered and decentered directional single OCT scans of the same subfoveal area. Studies investigating choroidal vascularity should be standardized by using the same OCT beam direction in all scans.