Functional anatomy, fine structure and basic pathology of the retinal vasculature

Abstract

The densely cellular retina with its intricate arrangement of neurons requires highly specialized circulations to meet its demanding metabolic requirements without compromising its extracellular space, which is a highly defined microenvironment conducive to neurotransmission, phototransduction and the complex interaction of metabolites, growth factors and vasoactive agents. The retinal circulation, which supplies the inner retina, is observed ophthalmoscopically as a regular geometrically arranged network of vessels and their three-dimensional complexity reflects the cellular density of the retinal neuropile. The caliber of directly viewed vessels is determined by the size of the red cell column, as the vessel walls and peripheral plasma layer are virtually transparent. The vessels accordingly appear wider during fluorescein angiography as dye mixes with the luminal plasma. As the vessel walls sclerose with age, stress or disease processes they become visible, due to reflected light on ophthalmoscopy, and obscure the red cell column to varying degrees. Abnormalities of the retinal circulation are key pointers to retinal dysfunction and disease and frequently highlight perturbations of the systemic circulation, e.g., diabetes, hypertension, and sickle cell disease. © 2007 Springer-Verlag Berlin Heidelberg.