Obesity and the microvasculature

Overweight and obesity are thought to significantly influence a
person's risk of cardiovascular disease, possibly via its effect on
the microvasculature. Retinal vascular caliber is a surrogate
marker of microvascular disease and a predictor of cardiovascular
events. The aim of this systematic review and meta-analysis was to
determine the association between body mass index (BMI) and retinal
vascular caliber. Relevant studies were identified by searches of
the MEDLINE and EMBASE databases from 1966 to August 2011.
Standardized forms were used for data extraction. Among over 44,000
individuals, obese subjects had narrower arteriolar and wider
venular calibers when compared with normal weight subjects,
independent of conventional cardiovascular risk factors. In adults,
a 1 kg/m(2) increase in BMI was associated with a difference of
0.07 μm [95% CI: -0.08; -0.06] in arteriolar caliber and 0.22 μm
[95% CI: 0.21; 0.23] in venular caliber. Similar results were found
for children. Higher BMI is associated with narrower retinal
arteriolar and wider venular calibers. Further prospective studies
are needed to examine whether a causative relationship between BMI
and retinal microcirculation exists.