Electroretinographic evaluation in adult diabetics

In cross-sectional fashion, we recorded the maximal combined response and 30-Hz flicker responses in 178 adult diabetics and 40 normal controls according to the recommendations of the International Society of Clinical Electrophysiology of Vision. The oscillatory potentials were extracted from the maximal combined response by high-pass filtering. The clear media and attached retina were criteria for inclusion in this study. The data were statistically analyzed with the expectation that this procedure may provide a new feature that could have some clinical significance. Timing delays occurred more frequently than amplitude reductions in the maximal combined response and flicker responses, while amplitude reductions were more common in the first and second oscillatory potentials. The hypernormal b-wave amplitude was rare. The summed amplitude of the oscillatory potentials was highly correlated with the total power of the oscillatory potentials (the frequency domain). A reduction of the second oscillatory potential amplitude was more common than a reduction of the summed amplitude or total power. The electroretinographic component that demonstrates retinal dysfunction in the earlier stage may be a valuable indicator. In the early stage, a delay in the a-wave time and a reduction in the second oscillatory potential amplitude were the most frequent abnormalities: analysis of variance demonstrated that the summed amplitude of the oscillatory potentials and second oscillatory potential amplitude and time were the most sensitive measures of the diabetic retina. Hence, the second oscillatory potential amplitude may be the most sensitive and valuable indicator representing a quantitative measure of overall retinal dysfunction.