Retinal vascular fractal dimension and cerebral blood flow, the CRESCENDO study

Abstract

Purpose The retinal vascular fractal dimension (FD) is a marker of retinal complexity of vascular tree. It has been associated with neurodegenerative and cerebrovascular diseases. Arterial spin labelling is a non‐invasive technique to evaluate the cerebral blood flow (CBF). The purpose of this study was to explore the relationship between retinal vascular FD and CBF. Methods Cross sectional analysis comprising 29 individuals aged 65 years and over from the Cognitive REServe and Clinical ENDOphenotype (CRESCENDO) cohort of healthy older adults. Retinal vascular FD was measured from fundus photographs using semi‐automated standardized imaging software “Singapore Eye Vessel Assessment (SIVA)” system. CBF was estimated in various gray matter regions from a 2D Pulsed arterial spin labelling sequence from MRI. Results A higher venular FD was associated with higher CBF in all cerebral regions of interest (p < 0.01). No significant associations were found between CBF and other parameters derived from SIVA or the central retinal arterial or venular equivalent. This association was stronger for opposite eye to handedness (p = 0.03). No relationship was observed between arterial FD and CBF (p > 0.07). Conclusions Venular FD was the main parameter associated to cerebral perfusion whereas retinal vascular calibers were not. It may be evaluated in clinical studies for early and non‐invasive detection of subclinical cerebro‐vascular pathologies including dementia and stroke.