OCT-A as cardiovascular imaging surrogate to demonstrate retinal capillary autoregulation during aerobic exercise

Introduction The retinal microvasculature provides a distinct optical window that offers insights into systemic microvascular health. It shares several structural and functional features with microvascular beds in organs such as the heart and brain, including endothelial behavior, hemodynamic patterns, and autoregulatory mechanisms. Optical coherence tomography angiography (OCT-A) is a non-invasive imaging modality which has emerged as a promising cardiovascular imaging tool for systemic vascular assessment. Purpose The objective of this prospective interventional study was to investigate retinal microvascular autoregulation and layer-specific flow density changes during standardized aerobic exercise (zone 1 running). Correlations between regular physical activity and fitness level (MET-min/week; Yo-Yo Intermittent Recovery test) and retinal flow alterations were tested to investigate whether OCT-A can be used as a new predictive surrogate for systemic microvascular function. Methods Retinal vascular structure of fifty-four moderately trained individuals was examined (age 27 ± 15 years, 35 males/19 females, MET-min/weak: 933±415 m; estimated VO₂ peak: 44.2±3.5 ml/kg/min). Central 3×3 mm² scans were captured by spectral-domain OCT-A (SD-OCT-A; Optovue). Flow density was regionally quantified in the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC), and subsequently compared pre- and post-exercise. In addition, Pearson's correlation coefficient was determined to assess the relationship between flow density and MET-min/week as well as estimated VO2peak. Results Participants' training lactate levels and heart rate confirmed aerobic exercise (post-exercise lactate: 2.24 ± 2.01 mmol/l; average HR: 140 ± 10 bpm). Analysis of the superficial capillary plexus and choriocapillaris metrics demonstrated microvascular stability (pSCP=0.83, pCC=0,55). However, a significant reduction in flow density was evident in the DCP (p < 0.03). The foveal avascular zone (FAZ) remained stable (p=0.77). neither fitness level nor physical activity status showed a significant impact on layer-specific flow density (p > 0.11). Conclusion The study demonstrated that OCT-A captured retinal microvascular autoregulation during standardized aerobic exercise, revealing distinct blood flow changes in the deep capillary plexus (DCP) that may indicate dynamic blood redistribution between retinal layers. Our findings establish OCT-A as a reliable, non-invasive imaging tool which provides reproducible information on the microvasculature and can thus be used to study the effects of exercise-based lifestyle interventions.OCT-A scans: SCP(A), DCP(B), CC(C), FAZ(D).