Electroretinogram in Unilateral Vascular Stress in Nondiabetic and Diabetic Subjects

Abstract

The oscillatory potentials (OP's) of the flash-elicited electroretinogram (ERG) are vulnerable to changes in retinal circulation such as occur in insulin-dependent diabetes mellitus (IDDM). In an earlier study it was shown that rod-isolated ERG's were more sensitive than cone-isolated ERG's to transient changes in the ocular perfusion pressure (OPP). In the present study, a comparison was made of the susceptibility of scotopic white, red, and blue flash OP's to transiently decreased perfusion in normals. Scotopic white flash OP's were then compared to those obtained in subjects with IDDM. The OPP was decreased by 20 and 40% through scleral suction in 10 normotensive healthy volunteers, as well as in 11 young subjects with IDDM. The data indicate that white flash OP's include early cone and later rod contributions. Both red and blue OP's were more variable than white OP's. For white flash OP's, component-specific changes to decreased OPP were found. The overall OP response profiles for the diabetic subjects during a stepwise short-term decrease in the OPP did not differ from those for nondiabetic subjects. The results are discussed in relation to retinal vascular autoregulation (AR) and choroidal blood flow.