Heart rate variability and the dynamic nature of the retinal microvasculature: providing insight into the brain-retina-heart link: the SABPA study

Controversy exists regarding the contribution of the autonomic nervous system (ANS) to the retinal microvasculature’s autoregulatory capacities. It was demonstrated that mean retinal vessel responses to systemic sympathetic stimulation were significantly reduced in sympathectomised eyes. Decreased heartrate-variability (HRV) indicates increased sympathetic nervous system (SNS) activity and modulation with a shift in the sympathovagal balance towards SNS predominance, vagal withdrawal or both. Increased SNS activity may precede volume-loadi