Comparison of ERGs recorded with skin and corneal-contact electrodes in normal children and adults

Purpose: Compare electroretinogram (ERG) responses to full-field stimuli recorded with corneal-contact and skin electrodes in healthy children and adults. Method: ERGs were recorded independently in two laboratories in children (aged 4-14 years) and adults (aged 20-62 years). A Burian-Allen (BA) electrode were used to test both children and adults in one laboratory. A Gold Foil (GF) electrode was used to test adults and skin electrodes to test children and adults in the other laboratory. Responses were recorded to full-field stimuli similar to those specified in the ISCEV Standard. Dark-adapted responses were also recorded over a 5 log unit range of stimulus energies. Results: All ISCEV rod and cone responses were recorded in every subject with skin electrodes as well as with eye-contact electrodes. BA and GF amplitudes and latencies were similar for the majority of ISCEV responses. The waveform morphology of rod and cone skin electrode responses was similar to corneal electrode responses in children and adults. GF electrode responses were on average 4 to 5 times larger than skin electrode responses recorded in the same laboratory. After scaling skin electrode responses by 4.5 the distribution of response amplitudes was found to be similar to that for the eye-contact electrodes in both children and adults. Dark-adapted responses were recorded to all stimulus intensities in every subject with each type of electrode. B-wave S-R functions were evaluated by fitting the Naka-Rushton equation. Vmax was similar for BA and GF electrode responses and this was about 4 times greater than for skin electrode responses. Log (sigma) was similar for GF and skin electrodes but these differed significantly from the BA electrode. Vmax and log(sigma) were similar in adults and children for BA and skin electrode responses. Conclusion: ERGs to full-field stimuli can be recorded successfully with either eye-contact or skin electrodes.