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Chapter 12

Tortuosity as an Indicator of the Severity

of Diabetic Retinopathy

Michael Iorga and Geoff Dougherty

12.1 Introduction

The retinal vasculature can be viewed directly and noninvasively, offering a unique and accessible window to study the health of the human microvasculature in vivo. The appearance of the retinal blood vessels is an important diagnostic indicator for much systemic pathology, including diabetes mellitus, hypertension, cardiovascular and cerebrovascular disease, and atherosclerosis [13]. There is mounting evidence supporting the notion that the retinal vasculature may provide a lifetime summary measure of genetic and environmental exposure, and may therefore act as a valuable risk marker for future systemic diseases [4]. Using its characteristics may provide early identification of people at risk due to diverse disease processes [5].

12.1.1 The Progression of Diabetic Retinopathy

Diabetic retinopathy is the most frequent cause of new cases of blindness among adults aged 20–74 years [6]. It is a progressive disease, beginning with mild nonproliferative abnormalities, characterized by increased vascular permeability, and progressing through moderate and severe nonproliferative diabetic retinopathy (NPDR) characterized by vascular closure, to proliferative diabetic retinopathy (PDR) with the growth of new blood vessels on the retina and posterior surface of the vitreous. Macular edema, marked by retinal thickening from leaky blood vessels, can develop at all stages of retinopathy.

In the early state of the disease, symptoms are mild or nonexistent. The curvature of a blood vessel influences its local flow hemodynamics and may result in

G. Dougherty ( )

California State University Channel Islands, Camarillo, CA 91320, USA e-mail: geoff.dougherty@csuci.edu

G. Dougherty (ed.), Medical Image Processing: Techniques and Applications, Biological

269

and Medical Physics, Biomedical Engineering, DOI 10.1007/978-1-4419-9779-1 12, © Springer Science+Business Media, LLC 2011

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