Changes in refraction caused by induction of acute hyperglycemia in healthy volunteers.

PURPOSE To determine whether the myopic changes and ocular hypotension after a glucose load are caused by hyperglycemia. METHODS Oral glucose tolerance tests were conducted on seven healthy young subjects with normal vision. The changes in the hematologic parameters and the refractive system were measured periodically for 150 minutes after the glucose load. RESULTS After the glucose load, there was an increase in plasma glucose level and the level of plasma osmosis, ocular hypotension, a myopic change in refractive power, shallowing of the anterior chamber, and a thickening of the lens. The degree of the myopic change exceeded the power of the residual accommodation. Normalization of the plasma glucose level led to a normalization of the intraocular pressure and a reversal of the myopic changes. CONCLUSIONS These findings suggest that the myopic changes that accompanied hyperglycemia were caused by a thickening of the lens resulting from a decrease in the tension of the zonule fibers of Zinn, and were secondary to ocular hypotension. Hyperopia appeared to be caused by the reversal of the myopia after normalization of plasma glucose levels.