Regional Variability in Choroidal Vascularity Index and Association with Intervortex Anastomoses in Polypoidal Choroidal Vasculopathy.

Purpose: To evaluate the regional variation in choroidal vascularity index (CVI) in polypoidal choroidal vasculopathy (PCV) and association with intervortex anastomosis (IA).

Methods: Fifty-one eyes with PCV were included. Volumetric optical coherence tomography (OCT) scan was acquired on a 6 X 6mm2 macula area and divided into 36 individual squares. CVI was calculated using an automated algorithm. The different regions were: central, superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN), inferior-nasal (IN). IA was detected using en-face OCT.

Results: The mean (SD) CVI of the whole macula was 61.01% (1.46), similar to all the other regions (pairwise comparison, all P >0.05). CVI range was 48.75%-69.48%. The mean (SD) coefficient of variation (CoV) was 1.9% (1.3).IA was present 64.7% of eyes. Eyes with IA had higher mean (SD) whole macula CVI (61.39% (1.43) versus 60.30% (1.26), P=0.01) and SFCT (265.8 µm (103.4) versus 190.1 µm (78.3), P =0.01) compared those without; and a lower mean (SD) CVI range (6.08% (2.38) versus 8.27% (4.13), P =0.04). Although the mean CVI CoV was lower in eyes with IA, 1.6% (0.8) versus 2.4% (1.8), this was not statistically significant, P=0.14.

Conclusion: Regional CVI variability may precede the formation of IA supporting the hypothesis that IA could be a compensatory mechanism for choroidal congestion.