Correlation between the Angiographic Choriocapillaris and the Structural Inner Choroid

Purpose: To assess the correlation between the choriocapillaris (CC) on optical coherence tomography (OCT) angiography and the inner choroid (IC) on structural OCT.Methods: In this prospective, cross-sectional, observational, pilot study, consecutive healthy subjects were imaged with a 6x6mm macular scan using OCTA PlexElite. Angiographic images of the CC were isolated using 10 μm-thick slab starting 21 μm posterior to the automatically segmented retinal pigment epithelium (RPE) band centerline. The structural en face OCT images of the IC were isolated using five 10 μm-thick slabs starting 11 to 51 μm posterior to the automatically segmented RPE band centerline. Retinal vessels masking was obtained by two methods: automated OCTA superficial vessel slab and automated structural OCT outer retina to CC (ORCC) slab. The en face OCT images were binarized for computation of the stromal index (SI). The flow deficits (FD) of the angiographic CC were correlated with the SI of the structural en face OCTs of the IC.Results: Twenty eyes of 20 subjects were enrolled. The strongest correlation was observed between the CC FD and the inner choroid SI of the 31-41 slab (IC SI_31-41) using the ORCC mask (R = 0.603, p = .005). Similar results were observed when the analysis was repeated when using IC SI_31-41 values obtained with the superficial vessels mask (R = 0.561, p = .01).Conclusions: The angiographic CC FD was significantly correlated with the structural inner choroidal stromal index. These findings suggest that there may be an opportunity to use structural OCT data to analyze the CC, which may allow longitudinal assessment from historical structural OCT datasets.