Abstract
Abstract: :
Purpose: To compare the diameter response of retinal arterioles and retinal thickness in patients with different stages of diabetic maculopathy during a rise in the arterial blood pressure. Methods: Nineteen normal persons (group A) and fifty–seven type 2 diabetic patients were studied. The patients consisted of three groups matched for diabetes duration, and for age and gender with the normal persons: Group (B) no retinopathy. Group (C) 1–4 microaneurysms. Group (D) hard exudates in the macula area not requiring laser treatment. The diameter changes of a large 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. After each examination retinal thickness was measured using optical coherence tomography. Results: The isometric exercise induced an increase in blood pressure of averagely 21.2±1.2 mmHg with no difference between the studied groups. Retinal autoregulation showed a significant decrease with increasing degree of diabetic maculopathy (p=0.01, Friedmann ANOVA). The diameter changes were –0.70%±0.48 in group A and –1.15%±0.44 in group B indicating preserved autoregulation, but 0.41%±0.49 in group C and 0.54%±0.44 in group D indicating loss of autoregulation. Regional comparison of retinal thickness showed values of 260µm±5.0 (group A), 257µm±4.5 (group B), 253µm±4.4 (group C), 279µm±5.3 (group D). The retinal thickness in group D with diabetic maculopathy differed significantly from the other groups (p=0.006, Friedmann ANOVA). Conclusions: Retinal autoregulation is impaired in diabetic patients with any retinopathy, whereas retinal thickness increases when retinopathy enters a maculopathy stage. This indicates that impaired autoregulation precedes the development of macular edema in diabetic patients.
Keywords: diabetic retinopathy • blood supply