Peripheral vascular disease is associated with abnormal arteriolar diameter relationships at bifurcations in the human retina

Abstract

A B S T R A C TArterial diameters at branch points are believed to conform to design principles that optimize circulatory efficiency and maintain constant shear stress across arterial networks. The objective of this study was to examine whether optimality at bifurcations is affected in individuals with atherosclerosis. Retinal images were analysed in normotensive men with abnormal ankle brachial index (n l 13) and healthy controls (n l 8), matched for age and clinic blood pressure. Compared with controls, men with peripheral vascular disease had adverse metabolic profiles (relative insulin resistance and greater total cholesterol levels). In healthy men, retinal arterial diameters at bifurcations conformed to predicted optimal values but in men with peripheral vascular disease, junction exponents deviated significantly from the optimum. Retinal arteriolar bifurcation angles did not differ significantly between the groups. Atherosclerosis is associated with abnormalities in the arteriolar network of the retina. In view of the importance of the endothelium in maintaining network co-ordination of branch diameters this is suggestive of a generalized abnormality of endothelial function in atherosclerosis.

Retinal Arteriolar Geometry is Associated with Cerebral White Matter Hyperintensities on Magnetic Resonance Imaging

“…We found no associations with branching angles (the association with PVD is based on few patients), consistent with some previous studies finding no link between angles and hypertension (31), peripheral vascular disease (15) and death with IHD and stroke (16). It is possible that angles may not predispose to or change in response to systemic disease.…”

“…An increased branching coefficient represents wider daughter vessels and a decreased branching coefficient indicates narrower daughters compared with the parent vessel; each may affect the energy required to deliver blood around the body and hence the efficiency of the circulatory system. Some studies suggest that this theory may be biologically true, for example abnormalities in branching coefficient have been associated with cognitive impairment (14), peripheral vascular disease (15) and ischaemic heart disease (IHD) (16).…”

Influence of Refractive Error and Axial Length on Retinal Vessel Geometric Characteristics

“…[5][6][7][8][9][10][11] More recently, new computer-based programs have been developed to perform quantitative assessments of geometric parameters of the retinal vasculature, such as retinal vascular tortuosity and branching angles. [12][13][14][15][16][17] The vascular network is believed to be organized to minimize shear stresses and work across the system, 18 -21 and these parameters may provide an indication of how closely a given network conforms to the geometrical ideal. In contrast with retinal vessel caliber measurements, which are generally performed at a fixed location relative to the optic disc and which measure only a single property of the retinal vessels, geometric network measures provide a better indication of the overall health of the vascular system.…”

“…In contrast with retinal vessel caliber measurements, which are generally performed at a fixed location relative to the optic disc and which measure only a single property of the retinal vessels, geometric network measures provide a better indication of the overall health of the vascular system. For example, Chapman et al 16 have demonstrated that retinal vascular diameters at bifurcation points deviated significantly from the optimal in subjects with peripheral vascular disease but conformed to optimal values in healthy controls. Low-birth-weight men have also been shown to have narrower bifurcation angles, 22 suggesting a mechanistic link between impaired fetal development and the subsequent development of cardiovascular diseases like hypertension.…”

Early Retinal Vascular Abnormalities in African-American Cocaine Users

“…In an ideal configuration, the bifurcation of arteries will have an optimal branching arrangement to facilitate effective blood flow6. Some studies have shown that the bifurcation angle is narrowed in subjects with hypertension7 or with low birth weight8, but not in subjects suffering from a peripheral vascular disease with abnormally low ankle/brachial indices9.…”