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P. Mitchell, E. Rochtchina, G. Liew, H. Li, T. Y. Wong, J. Wang; Association of Retinal Vascular Fractal Dimension and Retinopathy Lesions in Older People Without Diabetes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1242.
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© ARVO (1962-2015); The Authors (2016-present)
To assess whether retinopathy in people without diabetes is associated with retinal vascular fractal dimension.
Of 3654 baseline participants aged 49+, 2335/ 3111 (75% of survivors) were examined after 5 yrs, and 1935/ 2581 (75.0% of survivors) after 10 yrs. Retinopathy lesions (hemorrhages, microaneurysms, hard/ soft exudates) were assessed from stereo retinal photos. Diabetes (defined by history/ fasting glucose) was excluded. Retinal vascular fractal dimension (Df) measures vascular bed density (or fullness), using image analysis software and disc-centered retinal photos. In right-eye data, associations between Df and prevalent or incident retinopathy were examined.
197/ 3041 (6.5%) non-diabetic participants had isolated retinopathy lesions (right eye) at baseline. After excluding these and people with ungradable photos, 1588 were at risk of incident retinopathy at 5 or 10 yrs. Overall cumulative retinopathy incidence was 9.9% in right eyes (similar by gender), increasing from 6.9% for ages <60 to 32.6% for ages 80+. Prevalent retinopathy increased from 4.4% to 12.6% at these ages. Df decreased with age (i.e. vascular bed became less dense); the proportion with the lowest Df quartile increased from 12.5% (age <60) to 63.0% (80+). After adjusting for age, sex, body mass, smoking, mean arterial BP and retinal vessel caliber, we found a U-shaped association between Df and either prevalent or incident retinopathy. Compared to those in middle 2 Df quartiles, both those in lowest (least dense) and highest (most dense) quartiles had increased odds of prevalent retinopathy (odds ratio, OR, 2.2, 95% confidence interval, CI 1.5-3.2 for the lowest, and OR 1.7, 95% CI 1.1-2.5 for the highest quartile). They also had an increased risk of incident retinopathy over 10 yrs (OR 1.4, 95% CI 0.9-2.2 for the lowest, and OR 1.8, 95% CI 1.2-2.7 for the highest quartile). These relationships with prevalent and incident retinopathy were stronger in people with hypertension or obesity.
Either low or high retinal vascular fractal dimension was associated with isolated retinopathy in non-diabetic persons, cross-sectionally and longitudinally. This suggests that Df may measure microcirculatory optimality or suscepibility. A similar U-shaped relationship was found between Df and incident coronary-heart disease mortality over 13 yrs in the BMES.
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