Choroidal Vessel Changes in Age-Related Macular Degeneration using Swept-Source Optical Coherence Tomography

Abstract

Purpose : The role of the choroidal vasculature in the pathogenesis of Age-related Macular Degeneration (AMD) remains only partially understood. Recent studies have assessed choroidal thickness (CT) in this disease using spectral-domain optical coherence tomography (OCT). Swept-source OCT (SS-OCT) has important advantages for choroidal imaging, including enhanced penetration and resolution along with automated segmentation. Furthermore, the acquired en face images can provide additional assessments of choroidal vascularity. Herein, we compare choroidal vascular features of AMD eyes with a control group using SS-OCT.

Methods : Multicenter, cross-sectional study. We recruited subjects with AMD and controls without any vitreoretinal disease (> 50 years). All participants were imaged with color fundus photographs used for AMD staging according to the AREDS classification, and with SS-OCT (3D volume) on the same visit. En face images of the choroidal vasculature were obtained and converted to binary images on ImageJ. Choroidal vascular density (CVD) was then calculated as a percent area occupied by choroidal vessels in the central macular region (a 6-mm diameter circle centered on the fovea), and reported as average CVD (all image slices considered) and mid-point CVD (only image slices within 13 µm of mid-point). CT was obtained using SS-OCT automated software. The central macular choroidal vascular volume (CVV) was calculated by multiplying the CT by the average CVD within this area. Multilevel mixed linear models were performed for analyses.

Results : We included 611 eyes of 328 patients, 85% (n= 520) with AMD (105 early, 320 intermediate and 95 late), and 15% (n= 91) controls. Univariate analysis revealed that average CVD in the macular region was significantly lower in eyes with AMD than controls (b= -0.007, p= 0.002). After controlling for confounding factors, we observed that this was due to a reduced average CVD in eyes with late AMD (b= -0.028, p= 0.039). Similar results were obtained for mid-point CVD (b= -0.021, p= 0.006). Controlling for age, CT and CVV did not differ between eyes with AMD and controls.

Conclusions : Our results demonstrate that choroidal vascular density is significantly reduced in more advanced stages of AMD. New imaging modalities should allow further exploration of the contributions of choroidal vessel disease to AMD pathogenesis.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.