VISUAL-EVOKED POTENTIALS AFTER PHOTOSTRESS IN NEWLY-DIAGNOSED INSULIN-DEPENDENT DIABETES PATIENTS

Background: The study was performed in order to ascertain whether elec trophysiological abnormalities in visual function exist in newly diagn osed diabetic patients. Methods: Visual evoked potentials (VEPs) were assessed under basal conditions and after photostress in normal contro l subjects and in newly diagnosed diabetic patients free of any fluore scein angiography signs of retinopathy. Results: In basal conditions V EP P100 latency was significantly increased in the diabetic: patients compared to controls (P<0.01), while N75-P100 amplitude was similar in both groups. After photostress N75-P100 amplitude (mean percentage de crement) was significantly higher in diabetic patients (P<0.01), while P100 latency (mean increment) and recovery time (time at which VEPs w ere superimposable on basal condition) were similar in the two groups. Conclusions: The impaired basal VEPs suggest an early involvement of conduction in the optic nerve. In contrast, the preserved recovery tim e after photostress indicates that a short duration of disease does no t induce physiopathological changes in macular function.