Measuring flicker induced vasodilation at a high spatial and temporal resolution in the human retina

Abstract

Neurovascular coupling (NVC) is a crucial process in which blood flow is dynamically adjusted to meet the metabolic demands of active neurons. In this study, we introduce an innovative method for in-vivo imaging of retinal blood vessel dilation in response to visible light stimulation, offering insights into the functional regulation of retinal blood flow. Using high-resolution, high-speed phase contrast imaging, we continuously monitored retinal vessel dynamics in eight healthy subjects, capturing precise temporal and spatial changes in vessel size under both stimulated and baseline conditions. We have measured a significant vessel dilation of 5.2% +/- 1.6% (4.4 um +/- 1.3 um) during flicker-stimulation compared to a dilation of 2.5% +/- 1% (2.1 um +/- 0.9 um) without stimulation. The flexibility of our method also allowed for the exploration of various acquisition and stimulation settings, broadening possibilities for investigating neurovascular coupling in the retina. This work not only enhances our understanding of neurovascular coupling but also has the potential to identify new biomarkers for vision-impairing conditions and neurodegenerative diseases.