Choriocapillaris flow deficits in polypoidal choroidal vasculopathy using swept source optical coherence tomography angiography

Purpose: To evaluate the choriocapillaris flow deficits (CCFD) on swept-source optical coherence tomography angiography (SS-OCTA) in eyes with unilateral polypoidal choroidal vasculopathy (PCV), fellow unaffected eyes, and to compare them with age-matched healthy controls. Methods: This study was a cross-sectional study which included treatment-naïve eyes with unilateral PCV (group 1), fellow unaffected eyes of patients with PCV (group 2), and normal eyes (group 3). Using the SS-OCTA, the Choriocapillaris (CC) slab was segmented from the structural optical coherence tomography (OCT) and the corresponding flow map was multiplied after signal compensation. The resultant image was evaluated for CCFD in equidistant squares measuring 1 × 1 mm, 1.5 × 1.5 mm, 2 × 2 mm, 2.5 × 2.5 mm, 3 × 3 mm, and 6 × 6 mm centered on the fovea. Results: The percentage of flow deficits were significantly increased (one-way ANOVA, P = 0.003 and P = 0.049) in the eyes with PCV as compared to the fellow eyes, and age-matched healthy controls. In the multiple pairwise comparison using post hoc Bonferroni, CCFD of 1 mm in group 1 and 2 (P = 0.019), group 1 and 3 (P = 0.003), and CCFD of 1.5 mm in group 1 and 3 (P = 0.044) were statistically significant. Correlation analysis showed no significant correlation between CCFD, age, Best corrected visual acuity (BCVA), foveal thickness (FT), and subfoveal choroidal thickness (SFCT) in our study. Linear regression analysis showed that the CCFD was negatively correlated with the distance from the foveal center in group 1 (β =-0.613, P = 0.046). Conclusion: Eyes with PCV demonstrated a significant flow impairment in the choriocapillaris layer as compared to the fellow unaffected eyes and age-matched healthy eyes.