Choroidal Vascular Density and Volume in Intermediate Age-related Macular Degeneration – the Influence of Subretinal Drusenoid Deposits

Abstract

Purpose : The pathophysiology of Age-related Macular Degeneration (AMD) associated subretinal drusenoid deposits (SDD) remains only partially understood. This study aimed to compare macular choroidal vasculature density and volume in intermediate AMD eyes with and without SDD, using swept-source optical coherence tomography (SS-OCT).

Methods : Multicenter, prospective, observational study, including patients with intermediate AMD. Participants underwent complete ophthalmic exam, color fundus photography (used for AMD staging according to the AREDS system) and spectral-domain OCT (to evaluate for the presence of SDD by two independent graders). SS-OCT (3D horizontal volume, 12 mm x 9 mm) en face images of choroidal vasculature were captured (using Bruch’s membrane as reference for flattening) and converted to binary images using ImageJ. Choroidal density was calculated as percent area occupied by choroidal vessels in a 6 mm diameter circular submacular region centered on the fovea. Choroidal thickness was obtained using SS-OCT automated software. The submacular choroidal vascular volume was calculated by multiplying the average choroidal vascular density by macular area and choroidal thickness. Multilevel mixed effect linear models (accounting for correlated outcomes between 2 eyes) were used for analyses.

Results : We included 185 eyes of 118 patients with intermediate AMD (113 female, 61.1%). Ninety-two percent (n=171) had classic drusen, 50.3% (n=93) had SDD, and 44.9% (n=83) presented with both. Univariate analysis revealed that increased age was significantly associated with decreased choroidal vascular volume (ß=-0.0004, p<0.001) and mean choroidal density (ß=-0.003, p=0.001). After controlling for age, the presence of SDD was significantly associated with reduced macular choroidal volume (ß=-0.003, p=0.007). Macular choroidal thickness in eyes with SDD (n=93, 0.017 mm ± 0.01) was significantly lower than in eyes without SDD (n=92, 0.019 mm ± 0.01). However, SDD were not correlated with mean choroidal density (p=0.063).

Conclusions : Submacular choroidal vascular volume is reduced in eyes with SDD as compared to eyes without these lesions in intermediate AMD. Our results are consistent with prior work showing reduced choroidal thickness in AMD patients with SDD, and provides evidence of choroidopathy as a possible factor in disease pathogenesis.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.