Retinal vascular caliber and brachial flow-mediated dilation: the Multi-Ethnic Study of Atherosclerosis.

Background and Purpose: Retinal vascular caliber changes have been shown to predict stroke, but the underlying mechanism of this association is unknown. We examined the relationship between retinal vascular caliber with brachial flow-mediated dilation (FMD), a measure of systemic endothelial function.
Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) is a population-based study of persons 45 to 84 years of age residing in 6 US communities free of clinical cardiovascular disease at baseline. Brachial FMD data were collected at baseline (July 2000 to June 2002), and retinal vascular caliber was measured from digital retinal photographs at the second examination, immediately after the first (August 2002 to January 2004). Data were available for 2851 participants for analysis.
Results: The mean brachial FMD was 4.39+/-2.79%. After adjusting for age and gender, brachial FMD was reduced in persons with wider retinal venular caliber (changes in FMD -0.25, 95% CI, -0.36, - 0.13; P<0.001, per SD increase in venular caliber). This relationship persists after adjusting for systolic blood pressure, serum total cholesterol, use of lipid-lowering and antihypertensive medication, body mass index, current smoking status, and hemoglobinA(1C) (-0.18; 95% CI -0.30, - 0.06; P=0.004, per SD increase in venular caliber). Brachial FMD was not associated with retinal arteriolar caliber.
Conclusions: Persons with wider retinal venules have reduced brachial FMD, independent of other vascular risk factors. This suggests that retinal venular caliber, previously shown to predict stroke, may be a marker of underlying systemic endothelial dysfunction.