OCTA Derived Vessel Skeleton Density Versus Flux and Their Associations With Systemic Determinants of Health

PURPOSE. To examine the associations of optical coherence tomography angiography (OCTA)-derived retinal capillary flux with systemic determinants of health. METHODS. This is a cross-sectional study of subjects recruited from the African American Eye Disease Study. A commercially available swept-source (SS)-OCTA device was used to image the central 3 x 3 mm macular region. Retinal capillary perfusion was assessed using vessel skeleton density (VSD) and flux. Flux approximates the number of red blood cells moving through vessel segments and is a novel metric, whereas VSD is a previously validated measure commonly used to quantify capillary density. The associations of OCTA derived measures with systemic determinants of health were evaluated using multivariate generalized linear mixed-effects models. RESULTS. A total of 154 eyes from 83 participants were enrolled. Mean VSD and flux were 0.148 +/- 0.009 and 0.156 +/- 0.016, respectively. In a model containing age, systolic blood pressure, diabetes status, hematocrit, and presence of retinopathy as covariates, there was a negative correlation between VSD and age (P < 0.001) and retinopathy (P = 0.02), but not with hematocrit (P = 0.85) or other factors. There was a positive correlation between flux and hematocrit (P = 0.02), as well as a negative correlation for flux with age (P < 0.001), systolic blood pressure (P = 0.04), and diabetes status (P = 0.02). A 1% decrease in hematocrit was associated with the same magnitude change in flux as similar to 1.24 years of aging. Signal strength was associated with flux (P < 0.001), but not VSD (P = 0.51). CONCLUSIONS. SS-OCTA derived flux provides additional information about retinal perfusion distinct from that obtained with skeleton density-based measures. Flux is appropriate for detecting subclinical changes in perfusion in the absence of clinical retinopathy.

Automated summary

This study examines the relationship between retinal capillary flux measured by optical coherence tomography angiography (OCTA) and systemic determinants of health. The results suggest that retinal capillary perfusion, as indicated by flux and vessel skeleton density (VSD), is associated with various systemic factors, such as age, blood pressure, diabetes status, and hematocrit. The findings highlight the potential of OCTA-derived measures to provide additional information about retinal perfusion and its relationship with overall health.