Comparison of the second and third oscillatory potentials with oscillatory potential power in early diabetic retinopathy.

We used an oscillatory potential power method (a measure of the summed oscillatory potential activity) based on fast-Fourier transform analysis to study the oscillatory potentials in early diabetic retinopathy. The method was used in 29 diabetic patients with no ophthalmoscopically visible diabetic retinopathy, 29 diabetic patients with early signs only and 27 control subjects. The reduction in oscillatory potential power was compared with the reduction in the second and third oscillatory potential amplitudes and increase in implicit time in the diabetic patients. The amplitude of the second oscillatory potential was slightly more resistant to diabetic retinopathy than was the amplitude of the third oscillatory potential. Because the oscillatory potentials were detected by means of a high-resolution technique, their implicit times seem to be as discriminating as the oscillatory potential power in the detection of early diabetic retinopathy.