Wang SB, et al. - This study offers a comprehensive description of a spectrum of retinal vessel measures including fractal dimension (Df). Also, their associations with indices of coronary artery disease (CAD) extent and severity, as well as hypertension and diabetes were also determined. Findings demonstrated an association between a range of retinal vessel measures and CAD extent and severity. Data indicated a relation of a sparser retinal microvascular network (smaller Df) to older age and female gender. Furthermore, it was observed that retinal vessel measures were associated with more diffuse and severe CAD, after accounting for the effect of media opacity.

Methods

• In an observational study i.e. the Australian Heart Eye Study (AHES), researchers surveyed 1680 participants presenting to a tertiary referral hospital for the evaluation of potential CAD by coronary angiography.
• Using semi-automated software, the Singapore ‘I’ Vessel Assessment (SIVA) tool, they quantified a range of newer retinal vessel geometric measures (Df, curvature tortuosity, and branching angle) from retinal photographs.
• Furthermore, they constructed a combined retinal score, intending to examine the joint effect of multiple retinal vessel parameters on CAD, comprising of those variables that were most strongly significant in multivariate analysis - Df, arteriolar curvature tortuosity, and retinal arteriolar calibre.
• An objective quantification of CAD was also undertaken using a range of measures obtained from coronary angiography.

Results

• Complete data was obtained from 1187 participants on retinal vessel measurements and coronary vessel evaluation.
• Findings demonstrated that retinal vascular Df and curvature tortuosity decreased with increasing age; women had significantly lower Df than men (p<0.003).
• Multivariable analysis revealed an association of straighter retinal vessels with CAD extent and Gensini scores (p<0.02).
• Accounting for media opacity by sub-group analysis in pseudophakic patients, it was seen that the combined retinal score was related to stenosis greater than 50% in any coronary artery segment (vessel score) and obstructive coronary stenosis in all three main coronary arteries (segment score) (p = 0.01).
• Furthermore, data reported an association of lower Df and narrower arteriolar branching angle with CAD vessel score (p<0.03).
• It was demonstrated in sex-stratified multivariate analyses that straighter arterioles were related to greater odds of CAD in men, and narrower venular branching angle was associated with CAD in women.