[Comparison between subtraction skin electrodes and corneal-contact electrodes in flash electroretinograms]

To compare electroretinogram (ERG) responses measured with a skin electrode with those from a corneal-contact electrode in healthy adults.

Sixty two eyes of 31 healthy adults (8 men and 23 women) were enrolled (mean age 34.0 +/- 8.1 years). ERG responses for full-field and single flash stimuli was recorded with skin electrodes and corneal-contact electrodes. Morphology of the ERG waveform, a-wave and b-wave amplitudes, b/a ratios, and a-wave and b-wave implicit times were compared between the two electrode measurements. Correlations between the two measurements were also examined.

All features of the ERG waveform were identifiable using the skin electrodes. In the skin electrode ERGs, a-wave and b-wave amplitudes, and the b/a ratios were smaller (p<0.001) and the a-wave and b-wave implicit times were shorter (p<0.001) than those in the corneal-contact electrode ERGs. The B-wave amplitudes, b/a ratios and the a-wave and b-wave implicit times showed significant correlations between the two electrodes (p<0.01). In 16 eyes the OP4 was detected as the b-wave.

The skin electrode ERG had shorter amplitudes and shorter implicit times than the corneal electrode ERGs, but corresponded well in its morphology to the corneal-contact electrode ERGs. Skin electrodes ERG would be useful for the examination of child patients and patients with corneal diseases. Further study is required for clinical application.