Name

286 - Dimension fractale vasculaire rétinienne et débit sanguin cérébral, une étude pilote

Ocular and brain microcirculation share embryological and histological similarities. The retinal vascular fractal dimension (FD) is a marker of retinal vascular complexity of the vascular tree. It has been associated with systemic disorders but also with neurodegenerative and cerebrovascular diseases. Arterial spin labeling (ASL) is a non-invasive technique to estimate cerebral blood flow (CBF). The purpose of this study was to explore the relationship between CBF, retinal vascular FD and other retinal vascular markers.

Cross-sectional analysis comprising 26 individuals ≥ 65 years old from the Cognitive REServe and Clinical ENDOphenotype (CRESCENDO) cohort of healthy older adults. Retinal vascular FD was measured from fundus photographs by using the semi-automated Singapore Eye Vessel Assessment (SIVA) software. CBF was estimated in brain vascular territories using a 2D pulsed ASL MR sequence. Associations between blood flow and retinal parameters were analyzed using linear regression models adjusted for age and sex.

CBF was positively associated to venular FD (R2=0.32, p=0.03). This association was stronger in the anterior versus posterior brain territories (R2=0.001 [p=0.35] vs. R2=0.16 [p=0.07], respectively). Global CBF was correlated to arteriolar branching angle (R2=0.23, p=0.01) and tortuosity (R2=0.20, p=0.02). Global CBF was not correlated with other SIVA parameters: arteriolar FD (R2=0.02, p=0.48), central retinal arteriolar equivalent (R2=0.02, p=0.41), central retinal venular equivalent (R2=0.01, p=0.51), venous tortuosity (R2=0.12, p=0.09), or venular branching angle (R2 =0.07, p=0.19).

This pilot study suggests that retinal that complexity summarized by the FD was associated with cerebral perfusion as well as retinal arteriolar tortuosity and branching angle. Non-invasive and easy exploration of the retinal vasculature may be used as a proxy measure, with the condition of retinal vessels possibly reflecting the condition of the cerebral vasculature.

It should be evaluated in larger prospective clinical studies for early and non-invasive detection of sub-clinical cerebro-vascular pathologies including dementia and stroke.