Chemical Engineering and Chemical Technology, Imperial College London
Doi
Abstract
Pathological changes in retinal microvasculature are known to be associated with
systemic diseases such as hypertension and diabetes, and may result in potentially
disadvantageous blood flow and impair oxygen distribution. Therefore, in order to
improve our understanding of the link between systemic diseases and the retinal
circulation, it is necessary to develop an approach to quantitatively determine the
hemodynamic and oxygen transport parameters in the retinal vascular circulation.
This thesis aims to provide more insights into the detailed hemodynamic features
of the retinal arterial tree by means of non-invasive imaging and computational
modelling. It covers the following two aspects: i) 3D reconstruction of the retinal
arterial tree, and ii) development of an image-based computational model to predict
blood flow and oxygen transport in realistic subject-specific retinal arterial trees. The
latter forms the main body of the thesis. 3D reconstruction of the retinal arterial tree
was performed based on retinal images acquired in vivo with a fundus camera and
validated using a simple 3D object. The reproduction procedure was found to be
feasible but with limited accuracy. In the proposed 2D computational model, the
smaller peripheral vessels indistinguishable from the retinal images were represented
by self-similar asymmetric structured trees. The non-Newtonian properties of blood,
and nonlinear oxyhemoglobin dissociation in the red blood cells and plasma were
considered. The simulation results of the computational model were found in good
agreement with in vivo measurements reported in the literature. In order to understand
the effect of retinal vascular structure on blood flow and oxygen transport, the
computational model was applied to subject-specific geometries for a number of
hypertensive and diabetic patients, and comparisons were made with results obtained
from healthy retinal arterial networks. Moreover, energy analysis of normal and
hypertensive subjects was performed using 3D hypothetical models. Finally, the
influence of different viscosity models on flow and oxygen transport in a retinal tree
and the advantage of low dimensional models were examined.
This study has demonstrated the applicability of the image-based computational
modelling to study the hemodynamics and oxygen distribution in the retinal arterial
network
