Associations between retinal microvascular structure and the severity and extent of coronary artery disease. 
Microvascular mechanisms are increasingly recognized as being involved in a significant proportion of coronary artery disease (CAD) cases, but their exact contribution or role is unclear.  We aimed to define the association between retinal microvascular signs and both CAD extent and severity.  1120 participants of the Australian Heart Eye Study were included.  Retinal vessel caliber was measured from digital retinal images.  Extent and severity of CAD was assessed using several approaches.  First, a simple scoring classifying participants as having one-vessel, two-vessel, and three-vessel disease was used.  Gensini and Extent scores were calculated using angiography findings.  After multivariable adjustment, significantly narrower retinal arteriolar caliber in women (comparing lowest versus highest quartile or reference) and wider venular caliber in men (comparing highest versus lowest quartile or reference) were associated with 2-fold and 54% higher odds of having at least one stenosis ≥50% in the epicardial coronary arteries, respectively.  Women in the third versus first tertile of retinal venular caliber had 92% and ∼2-fold higher likelihood of having higher Gensini and Extent scores, respectively.  Women in the lowest versus highest tertile of retinal arteriolar caliber had greater odds of having higher Extent scores, OR 2.99 (95% CI 1.45-6.16).  In men, non-significant associations were observed between retinal vascular caliber and Gensini and Extent scores.  An unhealthy retinal microvascular profile, namely, narrower retinal arterioles and wider venules was associated with more diffuse and severe CAD among women.