Extended Zone Retinal Vascular Caliber and Risk of Diabetic Retinopathy in Adolescents with Type 1 Diabetes.

OBJECTIVE: Retinal vascular caliber has been linked to diabetic retinopathy (DR). Newer imaging technologies allow analysis of retinal vascular caliber beyond the standard areas surrounding the optic disc. We investigated the vascular caliber in extended zones in prediction of DR in adolescents with type 1 diabetes. DESIGN: Prospective, longitudinal study SUBJECTS: Adolescents (n=904) who attended the diabetes complications assessment service at The Children's Hospital at Westmead METHODS: Retinal caliber was assessed from baseline retinal photographs with a semi-automated computer software Singapore I Vessel Assessment (SIVA): "Standard zone" retinal vessel calibers were summarized as Central Retinal Arteriolar (CRAE) and venular equivalents (CRVE); "extended zone" vessels (>two disc diameters from the optic disc margin) as mean width of arterioles (MWa) and venules (MWv). . MAIN OUTCOME MEASURES: Retinal vessel calibers at baseline (upper three quartiles vs lowest quartiles, Q2-4 versus Q1) and moderate DR (stage 3 or above) were analyzed using multivariable generalized estimating equations, with results expressed as odds ratios (OR) and 95% CI. RESULTS: Among the 904 participants, baseline mean (±SD) age was 14.0±1.5 years, HbA1C 8.5±1.3 % and median diabetes duration 4.6 years. After median 3-years follow-up, 15% adolescents developed moderate DR. Wider extended zone retinal arteriolar caliber (MWa; OR 3.6 (95% CI 2.06-6.1, comparing Q2-4 vs. Q1) and venular caliber (MWv OR 4.2 (2.2-7.5) predicted moderate DR, after adjusting for HbA1C and blood pressure. Standard zone CRAE and CRVE were not associated with moderate DR. CONCLUSIONS: Extended zone retinal vessel caliber predict moderate DR in adolescents with type 1 diabetes.