Retinal Capillary Density and Perfusion Measures in the Framingham Heart Study

Abstract

Purpose : To describe optical coherence tomography angiography (OCTA) derived retinal vascular density and perfusion measurements in the Framingham Heart Study (FHS).

Methods : A prospective, IRB-approved study was conducted from 2020-2022 among the Offspring Generation (Exam 10) and OMNI-1 (Exam 5) cohorts (Framingham, MA). Foveal-centered 3x3 mm2 OCTA, and Axial Length (AL) were acquired on both undilated eyes (starting on the right eye) of each subject using commercial instruments. Images were rated as “Excellent”, “Good”, “Suboptimal”. “Excellent” and “Good” images were quantified for Vessel Skeleton Density (VSD), Vessel Area Density (VAD) and Flux in the Superficial Retinal Layer (SRL), Deep Retinal Layer (DRL) and Full Retinal Thickness (FRT). Welch’s t-tests were used to compare differences between males and females. Data was split between eyes with higher values in SRL “Higher VSD” and eyes with lower values in the SRL “Lower VSD”. Linear mixed effect models were used to estimate the effects of age, gender, axial length, and retinal layer (SRL and DRL) in retinal perfusion values VSD, VAD, and Flux while accounting for participant-specific random effects for correlations within the same eyes of individuals.

Results : 962 subjects were recruited (mean age 75±7, 59% female) and 1244 undilated eyes (72%) had usable OCTA data with a slight preponderance of usable data originating from the right eye (52%) . Mean VSD among all subjects was 0.143±0.008. Females showed higher VSD in both the SRL (p=0.013) and FRT (p=0.02) compared to males. In contrast, the VSD in the DRL was slightly greater in males compared to females (p=0.01). VSD in the SRL decreased 0.00033 (CI -4.32e-04, -0.00023, p<0.001) per year of age when controlling for gender, axial length, layer and image quality. Notably, our analyses revealed an interaction between age and retinal layer (SRL and DRL). We observed that VSD in the SRL decreases 0.000096 more than the DRL per year of age (CI -3.17e-06, 0.0002, p=0.058). This relationship was present and statistically significant in eyes with lower VSD. (Table 1 and Figure 1)

Conclusions : We report data showing OCTA derived retinal density and perfusion parameters in the FHS cohort. There are significant biologically relevant associations between retinal capillary perfusion and demographic, image quality and image acquisition parameters that are important to account for in large scale studies.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.