Abstract
Abstract: :
Purpose: To determine the relationship between the changes in optic nerve head (ONH) circulation and the level of plasma endothelin–1 (ET–1) during the glucose tolerance test (GTT). Methods: Twenty–six healthy volunteers with normal GTT, and 15 patients with mild hyperglycemia and abnormal GTT were studied. The ONH circulation (square blur rate [SBR] value), blood pressure, intraocular pressure (IOP), blood glucose, blood insulin, and plasma ET–1 were determined before and every hour up to 3 hours after an oral intake of 75 grams of glucose. Results: The SBR increased in the controls at all times during the GTT, but it decreased significantly in the hyperglycemia group (P <0.05). Before the GTT, the plasma ET–1 level was not significantly different in the two groups, however, the level increased 1 hour after the oral GTT in the abnormal glucose tolerance group (P <0.05). No significant changes were observed in mean blood pressure or IOP. Conclusions: ONH circulation increased after glucose intake in the normal glucose tolerance group and remained high even after the blood glucose level had returned to its baseline. The decrease in ONH circulation in the abnormal glucose tolerance group was attributed partly to the increased ET–1.
Keywords: diabetes • optic flow