Abstract
Abstract: :
Purpose:To study the diameter response of retinal arterioles in patients with different stages of diabetic maculopathy during a rise in the arterial blood pressure. Methods:Twenty–four type 2 diabetic patients were studied. The patients consisted of three groups matched for age, gender, and duration of diabetes. Group (A) no retinopathy, Group (B) 1–4 microaneurysms, Group (C) hard exudates in the macula area. The diameter changes of a retinal arteriole were measured continuously using the Retinal Vessel Analyzer (RVA, Imedos, Germany) before, during, and after a rise in blood pressure induced by isometric exercise when lifting a hand weight in one arm. Blood pressure was measured on the other arm using cuff technique. Results:The isometric exercise induced an increase in blood pressure of averagely 25.8±2.6 mmHg with no difference between the studied groups. Retinal autoregulation showed a significant decrease with increasing degree of diabetic maculopathy (p=0.03, ANOVA). The diameter changes were –1.58%±0.82 in group A indicating preserved autoregulation, 0.70%±0.63 in group B, and 1.05%±0.66 in group C indicating loss of autoregulation. Conclusions:The results are in accordance with previous studies suggesting that impaired autoregulation may be involved in the pathogenesis of diabetic maculopathy. This can be estimated non–invasively and in vivo using the Retinal Vessel Analyzer.
Keywords: retina • diabetic retinopathy • blood supply