Microaneurysm number and distribution in the macula of Chinese type 2 diabetics with early diabetic retinopathy: a population-based study in Kinmen, Taiwan

To explore the number and distribution of microaneurysms (MA) in the macula of type 2 diabetics in Kinmen, Taiwan and associated risks for early diabetic retinopathy (DR). A baseline mass screening extracts 971 type 2 diabetics between 1991 and 1993 and follow-up eye screening at 1999 was then done. Number of MA was counted and associated systemic factors collected from a centered 45° color fundus photograph of dilated eyes of type 2 diabetics (Topcon-NW5). Thirty-three (6.2%, n = 527) had MA retinopathy. Those with one eye involved (n = 26) had two mean MA; those with bilateral involvement (n = 7) had four mean per eye. Most MA were located temporally (mean MA = 0.79), then superiorly (mean = 0.58), inferiorly (mean = 0.46) and nasal (mean = 0.28). MA occurred at the 6,000-μm outermost ring (mean = 1.51), then the 3,000-μm ring (mean = 0.35), the 1,500-μm ring (mean = 0.26) and center 500 μm circle (mean = 0.01). After adjusting for confounding factors, early DR with MA was associated with longer duration of type 2 diabetes [odds ratios (OR) = 1.10, 95% confidence interval (CI) 1.00–1.21], higher glycosylated hemoglobin (OR = 1.36, 95%CI 1.11–1.66) and wider waist circumference (OR = 1.04, 95%CI 1.01–1.07). Our photograph grading system suggests that MA number and distribution at the macula may reflect severity of early DR and is a valid tool for predicting the progression of DR. Identifying those factors associated with MA only DR is important in developing prevention strategies for this early microvascular complication of type 2 diabetes.