Abstract
Purpose: :
Fractal analysis provides a global index of the geometric complexity and optimality of vascular networks. The aim of this study was to investigate the relationship between fractal measurements of the retinal vasculature and hypertension.
Methods: :
This was a multi-ethnic Asian population-based study which included 4,046 retinal photos of Chinese, Malay and Indian persons aged 24 to 95 years residing in Singapore. Blood pressure (BP) was evaluated with a digital automatic BP monitor (Dinamap model Pro 100V2; Criticon, Norderstedt, Germany). We identified 1679 participants with hypertension, defined as systolic BP ≥ 140 mmHg, diastolic BP ≥ 90mmHg, or self-reported physician diagnosed hypertension, and 2367 controls. The retinal fractal dimension (Df) was quantified from digitised fundus photographs using a computer-based program.
Results: :
The mean Df was 1.45 ± 0.03 in the population. Lower Df was associated with an increased prevalence of hypertension, after adjusting for age, gender, race, diabetes, body mass index, total cholesterol, low density lipoprotein, blood glucose, creatinine and smoking (odds ratio [OR] 2.64, 95% confidence interval [CI] 1.56, 4.47 and OR 1.91, 95% CI 1.18, 3.10, OR 1.50, 95%CI 0.93, 2.43; comparing 1st, 2nd and 3rd to 4th quartile of Df). Persons with lower Df were more likely to have hypertension (OR 1.29, 95% CI 1.04, 1.60 for every standard deviation decrease in Df). Such associations were similar in Chinese (OR 1.33, 95% CI 1.00, 1.76), Indians (OR1.10, 95%CI 0.61, 1.99) and Malays (OR 1.29, 95%CI 0.82, 2.04)
Conclusions: :
Persons with hypertension are more likely to have reduced complexity and rarefaction of the retinal vasculature.
Keywords: imaging/image analysis: clinical • retina • clinical (human) or epidemiologic studies: risk factor assessment