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Abstract #5683 Published in IGR 2-1
Effects of insulin on retinal and pulsatile choroidal blood flow in humans
Polak K; Dallinger S; Polska E; Findl O; Eichler HG; Wolzt M; Schmetterer LArchives of Ophthalmology 2000; 118:55-59
BACKGROUND: Insulin induces vasodilation in several tissues, including skeletal muscle and kidneys. : To investigate whether insulin may contribute to ocular blood flow regulation. METHODS: The study was performed in a balanced, randomized, placebo-controlled, single-masked, three-way, crossover design in nine healthy male subjects. Each subject received two doses of insulin (1.5 or 3 mU/kg per minute) or placebo on three different study days. Measurements of fundus pulsation amplitude with laser interferometry to assess pulsatile choroidal blood flow, of retinal blood flow with the blue-field entoptic technique, and of mean blood flow velocity in the ophthalmic artery with Doppler sonography were performed under euglycemic clamp conditions over 120 minutes. RESULTS: Hyperinsulinemia significantly increased fundus pulsation amplitude (1.5 mU/kg per minute: 8.7% ± 1.1% versus baseline; 3 mU/kg per minute: 13.2% ± 2.3% versus baseline; p < 0.001 versus placebo (analysis of variance)) and mean blood flow velocity (1.5 mU/kg per minute: 10.0±4.3% versus baseline; 3 mU/kg per minute: 6.6±3.5% versus baseline; p=0.03 versus placebo). Retinal blood flow did not increase during administration of insulin (1.5 mU/kg per minute: 6.4±8.0% versus baseline; 3 mU/kg per minute: 8.0±5.1% versus baseline; p=0.99 versus placebo). Neither the effect in the choroid nor that in the ophthalmic artery was dose-dependent. CONCLUSIONS: Hyperinsulinemia significantly increases choroidal blood flow and mean blood flow velocity in the ophthalmic artery. In contrast, retinal blood flow was not influenced by hyperinsulinemia. The maximum effective dose of insulin for ocular hemodynamics is likely to be within the physiological range.
Dr. K. Polak, Department of Clinical Pharmacology, Vienna University, Vienna, Austria
Classification:
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
