Abstract
Abstract: :
Purpose: Well-established cardiovascular risk factors include age, elevated blood pressure, smoking, obesity and blood lipid levels. Recent findings from the U.S. Atherosclerosis Risk in Communities Study (ARIC) and preliminary data from the Australian Blue Mountains Eye Study (BMES) suggest that retinal microvascular abnormalities may predict subsequent stroke, independent of other known vascular risk factors. The purpose of this report is to describe the cross-sectional relationships between quantitative measures of retinal vessel diameter, age and blood pressure in a subsample (n=1500) of the BMES population. Methods: Right eye retinal photographs of participants in baseline BMES (n=3654, aged 49+ years during 1992-4) were digitized using standard techniques. The diameters of all retinal arterioles and venules passing through a circumferential zone 0.5 to 1.0 disc diameters from the optic disc margin were measured objectively using a computer-based program, developed for the ARIC and modified for the Beaver Dam Eye Study. The summarized estimates for central retinal arteriolar and venular equivalent (CRAE, CRVE) represent average diameters of arterioles and venules. Results: Both retinal arterioles and venules narrowed significantly with increasing age. Mean CRAE was 189 um for persons less than 60 years and 175mm for persons aged 80 years or older. Similarly, mean CRVE was 227 um for persons less than 60 years and 209mm for persons aged 80 years or older. The reduction in arteriovenous ratio (AVR) associated with age was less obvious. After adjusting for sex and systolic (SBP) blood pressure, or sex and diastolic (DBP) blood pressure, CRAE reduced by 2.8 um, or 4.4 um, respectively, for each increasing decade of age. After adjusting for age and sex, CRAE reduced by 1.3 um and 1.8 um for each 10 mmHg increase in SBP and DBP, respectively. After further adjustment for smoking and body mass index, the significant inverse associations either between CRAE and SBP, or between AVR and SBP, remained. Conclusion: This study confirms ARIC findings that generalized arteriolar narrowing is monotonically related to blood pressure. It suggests long-standing structural vascular effects of elevated blood pressure.
Keywords: 355 clinical (human) or epidemiologic studies: risk factor assessment • 554 retina • 309 aging