Vessel Density and Foveal Avascular Zone (FAZ) Size among a Community Sample of Older Adults from the Eye Determinants of Cognition (EyeDOC) Study

Abstract

Purpose : Measures of retinal vessel density (VD) and foveal avascular zone (FAZ) using Optical Coherence Tomography Angiography (OCTA) are often made clinically to evaluate retinal health in individual patients. However, the normative distribution of VD and FAZ in the general population and as a function of age has not been well characterized, due to a dearth of OCTA data in non-clinical populations. Here we describe VD and FAZ in an aging population-based bi-community sample from the EyeDOC study.

Methods : Participants from Jackson, MS (all black) and Washington County, MD (all white) were enrolled in the EyeDOC study. OCTA was used to measure macular VD (% of area covered by vessels) in the superficial vascular complex (SVC), intermediate capillary plexus (ICP) and deep capillary plexus (DCP) in a 6x6 mm² area, and FAZ in a 3x3 mm² area. Distributions of the OCTA metrics were stratified by layer and averaged to get overall measures by gender and community. T-test and one-way ANOVA test were applied for comparison between gender, community and across age strata. Linear regression was used to examine the trends on OCTA metrics across age strata.

Results : Vessel density data were available from 513 eyes of 485 participants (44% black; 58% female; mean age 80 years [range: 73-95 years]) and FAZ data were available from 292 eyes of 277 participants. The mean VD in SVC was 45.73% and 49.70%, respectively, among Jackson and Washington County participants (P value <0.001). The mean VD in DCP was higher in Jackson participants (23.63%) than Washington County participants (20.90%, P value <0.001). The mean VD in all three layers were statistically different across age strata. Further, linear regression indicated the mean VD in SVC declined across age strata, while no significant decline was found for mean VD in ICP and DCP, after adjusting for gender, community, axial length and signal strength index (Table 1). On average, men and women had equivalent VD in the SVC, ICP and DCP (P value=0.45, 0.32, 0.87). The mean FAZ differed by community (Jackson: 0.38, Washington: 0.25, P value <0.001) and gender (female: 0.32, male: 0.25, P value <0.001) without a decline across age strata (Table 2).

Conclusions : Among the bi-community sample of older adults, VD in SVC and DCP and FAZ differed by community. There is a declining trend for VD in SVC across age strata.

This is a 2020 ARVO Annual Meeting abstract.