The retinal vasculature is unique in that, unlike any other systemic vascular bed, it can be assessed directly and non-invasively in vivo. Optometrists routinely evaluate the state of the retina and its microvasculature as part of any normal ophthalmic assessment and, if considered carefully, such an evaluation has the potential to provide a unique insight into general vascular health. Advances in imaging technology have enhanced our ability to evaluate and document changes in the retinal vasculature over time and the recent introduction of new objective retinal image analysis techniques has the potential to improve significantly the accuracy and usability of quantifiable retinal vessel parameters such as calibre, arteriovenous ratio (AVR) and vessel tortuosity. 

This article will aim to outline the relevant anatomy and physiology of the retinal vasculature and summarise the current evidence linking alterations in the retinal microvasculature to the occurrence of ocular and systemic vascular disease, with reference to the recent developments in imaging technology that are aiding our ability to make these links now and into the future.