RETINAL VASCULAR IMAGING IS A SUBCLINICAL PREDICTOR OF THE INCIDENCE AND PROGRESSION OF DIABETIC RETINOPATHY IN ASIANS WITH DIABETES

Abstract

Purpose: Most previous studies on the relationship of retinal microvascular changes and diabetic retinopathy (DR) are based on cross-sectional data. We examined prospectively the association of a range of retinal vascular parameters with 6-year incidence and progression of DR in a population-based cohort with diabetes.

Methods: We conducted a prospective, population-based cohort study of Asian Malay persons 40-80 years at baseline in 2004-2006 (n=3,280 response rate 78.9%), with a 6-year follow-up in 2010-2012 (n=1,900 response rate 72.1%). Retinal vascular parameters (tortuosity, branching angle, fractal dimension and caliber) were measured from baseline retinal photographs using a computer-assisted program (Singapore I Vessel Assessment, SIVA). DR was graded from baseline and follow-up retinal photographs using the modified Airlie House classification system. Incidence of DR was defined as severity level of 15 or greater at the follow-up visit in those free of DR at baseline. Progression of DR was defined as an increase in the severity level by 2 or more steps at the follow-up visit in those who had no DR or nonproliferative DR (NDR) at baseline. Log-binomial models with expectation-maximization algorithm were used to estimate relative risk (RR, 95% confidence interval).

Results: A total of 434 persons with diabetes participated in the 6-year follow-up examination. Of the 315 persons with no DR at baseline, 18.7% (n=59) developed any DR at follow-up. Greater tortuosity of retinal arterioles and venules (RR per SD increase, 1.31 [1.08-1.60], 1.27 [1.06-1.53], respectively), wider arteriolar and narrower venular calibers (RR per SD increase, 1.56 [1.17-2.09], 0.68 [0.52-0.89], respectively) were independently associated with incident DR, after adjusting for age, gender, diabetic duration, hbA1c level, blood pressure, body mass index, total and HDL cholesterol levels at baseline. Of the 421 persons with no DR or NDR at baseline, 18.8% (n=79) had progression of DR. Only greater tortuosity of retinal arterioles (RR per SD increase 1.22 [1.00-1.49]) was independently associated with 6-year progression of DR after multivariate adjustment.

Conclusions: Alterations in retinal geometric pattern and vessel caliber were associated with incident DR and its progression, suggesting that retinal vascular imaging may be a pre-clinical marker of DR in patients with diabetes.