Ocular Determinants of Peripapillary Vessel Density in the African American Eye Disease Study

Abstract

Purpose : Radial peripapillary capillary vessel density (RPC VD) is significantly reduced in glaucoma, but we do not know if vascular changes exist before glaucoma. Additionally, we do not understand other ocular anatomic factors that may contribute to reduced RPC VD and possibly even to glaucoma. This population-based, cross-sectional OCTA study evaluated the ocular determinants of RPC VD in African Americans (AA) without pre-existing ocular disease.

Methods : 6x6mm optic nerve spectral domain-optical coherence tomography angiography (OCTA) scans were performed using CIRRUS 5000 HD-OCT with AngioPlex (ZEISS, Dublin, CA), on participants of the African American Eye Disease Study (AFEDS), which consisted of AA 40 years and older in Inglewood, California. Patients with glaucoma, severe non-proliferative diabetic retinopathy (NPDR), and PDR were excluded. RPC VD was quantified using custom software. Multivariate linear regression was performed to determine factors associated with RPC VD with a significance level set at 0.05. Candidate variables included: age, signal strength, axial length, intraocular pressure, central corneal thickness, mean retinal nerve fiber layer (RNFL) thickness, and visual field mean deviation. The contribution of each variable was assessed with the magnitude of standardized regression coefficients (SRC).

Results : 3840 eyes of 2025 subjects received OCTA imaging. Of these, 1473 eyes from 1042 subjects had signal strength ≥ 7 out of 10 and had good quality images based on a standardized image quality grading algorithm. 1042 eyes from 1042 subjects were analyzed. Controlling for signal strength and age, the ocular variables significantly associated with reduced RPC VD in the final multivariate model were: thinner mean RNFL thickness (β=0.0023, per micron, p<0.0001, SRC=0.565) and longer axial length (β=-0.0050, per mm, p<0.0001, SRC=-0.105). The model R² was 0.68.

Conclusions : The most influential ocular factors associated with reduced RPC VD in healthy African American eyes were: thinner mean RNFL and longer axial length. These results support the idea that axially myopic eyes may have reduced perfusion and thus may be at higher risk for having or developing glaucoma.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.