Pattern Visual Evoked Potentials in Patients with Type II Diabetes Mellitus

PURPOSE: To evaluate cortical and retinal activity by pattern visual evoked potentials (PVEP) in patients with type II diabetes mellitus. METHODS: PVEP was recorded in 40 diabetic patients including 20 subjects with non-proliferative diabetic retinopathy (NPDR) and 20 others without any retinopathy on fundus photography, and compared to 40 age- and sex-matched normal non-diabetic controls. RESULTS: P100 wave latency was significantly longer in diabetic patients as compared to normal controls (P<0.001); both diabetic subjects without retinopathy and those with NPDR had significantly longer P100 latency than controls (P<0.001 for both comparisons). There was significant reduction in N75 (P=0.037) and P100 (P=0.001) amplitudes in diabetic subjects. No correlation was observed between VEP amplitude or wave latency, and the level of glycemia or duration of diabetes mellitus. CONCLUSION: Increased PVEP latency may be a sign of retinal ganglion cell damage which takes place before the appearance of the first ophthalmoscopically detectable signs of diabetic retinopathy. PVEP may be considered as a method for detecting prediabetic retinopathy and has the potential to reduce diabetic complications.