Influence of Refraction on Widefield Retinal and Choroidal Vascular Metrics in Optical Coherence Tomography Angiography in a Caucasian Population

Purpose: Refraction-related differences in retinal and choroidal vascular metrics have been reported using optical coherence tomography angiography (OCTA), primarily within the central fundus. This study aimed to establish normative vascular reference values for the retina and choroid using widefield swept-source OCTA (WF-SS-OCTA), stratified by spherical equivalent (SE), to characterize associations between refractive status and OCTA-derived vascular measurements extending beyond the central fundus. Methods: In this prospective single-center study, healthy volunteers underwent WF-SS-OCTA at the University Hospital Münster, Germany. Vascular metrics of the superficial capillary plexus (SCP) and the choroid were quantified using AngioTool software. Associations between SE and vascular metrics were analyzed using linear quantile mixed models accounting for inter-eye dependency and sex-specific effects. Results: A total of 414 eyes from 216 participants were analyzed. Exploratory analyses suggested an inverse relationship between SE and vascular endpoints in the SCP. In sex-stratified analyses, higher SE tended to be associated with increased flow density, vessel length, and junction counts in men, whereas junction counts tended to decrease in women. In the choroid, no clear associations were observed in the overall cohort; however, exploratory sex-specific analyses indicated potential associations between increasing SE and reduced junction density and total vessel length in women. Significant sex-related differences were observed for baseline junction counts and SE-related total vessel length trends. Conclusions: Refractive status may influence WF retinal and choroidal vascular metrics, with several parameters showing potential sex-specific patterns. Translational Relevance: The resulting refraction- and sex-stratified normative dataset may serve as a practical reference framework for the interpretation of WF-SS-OCTA measurements, whereas future studies incorporating axial length (AL) measurements are needed to refine anatomic interpretation.