Factors associated with peripapillary OCTA perfusion density: separating capillary and large-vessel contributions in an Asian cohort.

PURPOSE: To quantify OCTA-derived peripapillary perfusion density in healthy adults and determine whether demographic, ocular, and systemic associations differ between capillary and large-vessel components. METHODS: This cross-sectional study included 554 healthy adults (1010 eyes) aged 21-86 years, without diabetes, systemic hypertension, or ocular disease, recruited at the Singapore National Eye Centre. Optic disc-centered 6×6-mm OCTA scans (Cirrus HD-OCT 6000) were used to quantify peripapillary perfusion density, including total, capillary, and large-vessel components. Regression models were applied to evaluate associations with demographic, systemic, and ocular parameters. RESULTS: Mean total, capillary, and large-vessel perfusion densities were 47.42 ± 5.80%, 32.32 ± 5.53%, and 20.14 ± 3.67%, respectively. Total (P for trend = 0.001) and capillary (P for trend = 0.010) perfusion densities were lower across older age groups, whereas large-vessel perfusion density did not differ significantly across age groups (P for trend = 0.879). Multivariable analyses demonstrated distinct associated-factor profiles across vascular compartments. Capillary perfusion density was negatively associated with age (β = -0.044, P = 0.002) and positively associated with axial length (β = 0.735, P < 0.001), retinal nerve fibre layer thickness (β = 0.122, P < 0.001), and signal strength index (β = 2.977, P < 0.001). Large-vessel perfusion density was negatively associated with axial length (β = -0.240, P = 0.014) and positively associated with intraocular pressure (β = 0.096, P = 0.017). CONCLUSIONS: Peripapillary perfusion density showed compartment-specific associated-factor profiles in healthy adults. Separating capillary and large-vessel components may improve interpretation of OCTA-derived measurements, but validation in disease cohorts is required.