ABSTRACT
To evaluate cortical and retinal activity by pattern visual evoked potentials [PVEP] in patients with type II diabetes mellitus. PVEP was recorded in 40 diabetic patients including 20 subjects with nonproliferative diabetic retinopathy [NPDR] and 20 others without any retinopathy on fundus photography, and compared to 40 age- and sex-matched normal non-diabetic controls. 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. 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.