Association between retinal vessels caliber and systemic health: A comprehensive review

The unique nature of the retinal microvasculature that permits non-invasive visualization has garnered interest as a potential method for detecting microvascular alterations indicative of systemic diseases. This concept, supported by advancements in imaging technologies, has been increasingly validated by studies linking retinal microvasculature with systemic conditions such as diabetes, hypertension, and cerebrovascular disease. Structural changes in the retinal microvasculature are associated with cardiovascular risk factors, metabolic diseases, and are significant predictors of systemic hypertensive damage and mortality. Given that most systemic diseases present life-long burdens and complications if undetected or untreated, the development of diagnostic tools like retinal vascular imaging becomes important for early detection, monitoring of disease progression, and facilitating timely interventions. Technological advancements have enabled objective and accurate quantification of retinal microvascular characteristics. We consolidate current literature on retinal vascular changes across various systemic health conditions, including metabolic diseases, cerebrovascular diseases, pregnancy complications, systemic inflammatory conditions, leukemia, human immunodeficiency virus infection, and COVID-19. We also emphasizes the need for dynamic parameters, an understanding of 3-dimensional vascular architecture, and larger-scale longitudinal studies to elucidate the temporal relationship between retinal vascular changes and systemic diseases, helping shape future diagnostic and monitoring approaches.