Non-Exudative Age-Related Macular Degeneration Foveal Avascular Zone Area, Foveal Vessel Density, and Ganglion Cell Complex Thickness

Abstract

Purpose : To quantify the effects of non-exudative Age-Related Macular Degeneration (AMD) on foveal microvasculature. We performed a retrospective observational study that evaluates the effect of AMD on foveal avascular zone (FAZ) area, foveal vessel density (FVD), and parafoveal ganglion cell complex (GCC) thickness using optical coherence tomography angiography (OCTA). We also analyzed the influence aging has on FAZ area, FVD, and GCC thickness.

Methods : OCTA images were analyzed using AngioVue software on Avanti SD-OCT systems from 144 consented subjects (251 eyes) aged 16 to 91 (mean±SD: 59.1±17.2 years) in this IRB-approved study. A 3x3mm region centered on the fovea in the superficial retinal capillary plexus was imaged, and FAZ area, FVD, and parafoveal (0.5mm to 1.5mm eccentricity) GCC thickness were calculated. Inclusion criterion was the presence of clinically diagnosed non-exudative AMD. Exclusion criteria were scan quality less than 55 and the presence of any other ocular disease entity. 23 control eyes (ages 35.2±17.2 years) and 25 AMD eyes (ages 72.6±8.5 years) were compared using multivariate analysis. Regression analysis using correlation coefficients was performed comparing age against FAZ area, FVD, and GCC thickness in all 251 eyes. Level of significance was set at P<0.05 for all analyses.

Results : The mean FAZ area and FVD was larger in the AMD eyes compared to controls (0.369 ± 0.029 mm² vs 0.266 ± 0.013 mm²; P=0.006 and 46.80%±0.82% vs 30.44%±0.96%; P<0.001, respectively). The mean GCC thickness was lower in AMD eyes compared to controls (109.88±2.21um vs 123.17±2.09um). Age showed a negative correlation with GCC thickness, with a decrease of 0.258 um per year (R²=0.079; P<0.001). There is no correlation between age and FAZ area or FVD (R²=0.014; P=0.085 and R²=0.004; P=0.319, respectively).

Conclusions : OCTA is a new technology that allows for non-invasive visualization and analysis of retinal microvasculature. Our study reveals that AMD eyes have enlarged FAZ area and higher capillary vascularity, which could not be explained by age, and thinner parafoveal GCC. Further larger studies are needed to corroborate these findings and to help define AMD’s influence on retinal microvasculature.

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