Technical Briefs

Assessment of Energy Requirement for the Retinal Arterial Network in Normal and Hypertensive Subjects

[+] Author and Article Information
D. Liu, N. B. Wood

Department of Chemical Engineering,  Imperial College London, South Kensington Campus, London SW7 2AB, UK

N. Witt, A. D. Hughes, S. A. Thom

Faculty of Medicine, Clinical Pharmacology, NHLI Division, International Centre for Circulatory Health,  Imperial College London, St Mary’s Campus, London W2 1NY, UK

X. Y. Xu1

Department of Chemical Engineering,  Imperial College London, South Kensington Campus, London SW7 2AB, UKyun.xu@imperial.ac.uk


Corresponding author.

J Biomech Eng 134(1), 014501 (Feb 09, 2012) (7 pages) doi:10.1115/1.4005529 History: Received March 21, 2011; Accepted December 09, 2011; Posted January 18, 2012; Published February 08, 2012; Online February 09, 2012

The retinal arterial network structure can be altered by systemic diseases such as hypertension and diabetes. In order to compare the energy requirement for maintaining retinal blood flow and vessel wall metabolism between normal and hypertensive subjects, 3D hypothetical models of a representative retinal arterial bifurcation were constructed based on topological features derived from retinal images. Computational analysis of blood flow was performed, which accounted for the non-Newtonian rheological properties of blood and peripheral vessel resistance. The results suggested that the rate of energy required to maintain the blood flow and wall metabolism is much lower for normal subjects than for hypertensives, with the latter requiring 49.2% more energy for an entire retinal arteriolar tree. Among the several morphological factors, length-to-diameter ratio was found to have the most significant influence on the overall energy requirement.

Copyright © 2012 by American Society of Mechanical Engineers
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Figure 1

A retinal image captured by a Zeiss FF450 plus fundus camera

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Figure 2

Hypothetical models of retinal arterial bifurcation for (a) normal subject, (b) hypertensive subject

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Figure 3

Illustration of the 3D hypothetical bifurcation and virtual downstream trees generated for outlet boundary conditions

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Figure 4

Flow division between the daughter branches in the hypothetical models. O-1 and O-2 represent the major and minor branches respectively

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Figure 5

Definition of symbols used in the mass conservation

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Figure 6

Contribution of individual terms to the overall energy requirement of the entire retinal arterial tree. Ed,tree is the energy required to overcome flow resistances of the entire tree; Em,tree is the energy consumption of blood for the entire tree whereas Ew,tree is the corresponding metabolic consumption of the vascular wall.

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Figure 7

Velocity distribution at the symmetric plane of the normal retinal bifurcation model




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