Digital imaging to characterize retinal vascular topography

Fundal examination offers a unique opportunity to non-invasively visualize, photograph, and subsequently analyze images of the retinal vasculature in vivo. Technology has developed rapidly, permitting retinal digital image analysis to be readily accessible to both researchers and practicing clinicians via commercial software. Over the past five years, large epidemiological studies have utilized retinal image analysis to help to characterize the influence of cardiovascular disease on retinal vascular topography. In this chapter, we describe the use of imaging analysis to measure blood vessel widths using microdensitometry. We provide an overview of the concept of optimization of a branching vascular structure, and the evidence that retinal circulation conforms to such optimization principals. We review how researchers have employed digital image analysis to characterize retinal vasculature in terms of these optimization principles, and how this has proved useful in providing quantitative measurements from retinal images that are more objective and less observer-driven than previous manual techniques. We speculate on a future application of telescreening of fundal images for individual cardiovascular risk stratification based on retinal vascular topography.