Structural changes in the eye's blood vessels are associated with a higher body mass index (BMI) and could signal the onset of other cardiovascular risk factors such as diabetes or hypertension, reports the International Journal of Obesity. A study of 1,608 six-year-old children from Sydney, Australia shows that greater BMI, weight, body surface area and waist circumference are associated with microvascular changes in small veins in the retina called venules and small terminal branches of retinal arteries called arterioles.
Bronwen Taylor and colleagues conducted the study in children because measurements of blood vessel diameter in adults may be skewed by blood pressure problems or other systemic diseases more commonly seen in adults than in children. The results confirm the work of previous studies on adults, showing that greater BMI, weight and body surface area are associated with wider retinal venules, while greater BMI and larger waist circumference correlated with narrower retinal arterioles. Changes in vessel structure of the retina may therefore constitute one of the earliest indications of microvascular damage.
The mechanism by which greater BMI causes such vascular changes is unclear however. Blood vessels can widen or narrow to regulate blood flow, and since obese people have greater total blood volume than their non-obese counterparts, wider venules would alleviate the larger blood volume associated with increased BMI. But this theory does not explain why arterioles would narrow.
The authors conclude that small vessel structural changes associated with greater body mass occur before other cardiovascular risk factors develop but whether these changes lay the foundation for an increased cardiovascular risk later in life remains to be determined.
Bronwen Taylor (University of Sydney, New South Wales, Australia)
Abstract available online.
(C) International Journal of Obesity press release.
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