Visual evoked potentials after photostress in newly diagnosed insulin-dependent diabetes patients

Background: The study was performed in order to ascertain whether electrophysiological abnormalities in visual function exist in newly diagnosed diabetic patients. Methods: Visual evoked potentials (VEPs) were assessed under basal conditions and after photostress in normal control subjects and in newly diagnosed diabetic patients free of any fluorescein angiography signs of retinopathy. Results: In basal conditions VEP 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 decrement) was significantly higher in diabetic patients (P<0.01), while P100 latency (mean increment) and recovery time (time at which VEPs were 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 time after photostress indicates that a short duration of disease does not induce physiopathological changes in macular function.