DTL versus skin electrodes in recording of multifocal pattern electroretinogram and multifocal photopic negative response.

OBJECTIVE

To compare the photopic negative response of the multifocal ERG (mfERG) and the multifocal pattern electroretinogram (mfPERG) using DTL electrode (E) vs skin electrode (E) in healthy young and old adults.

METHODS

Ten "Young" [20-27 years] and eight "Old" [60-72 years] participants took part in this study. The electrophysiological responses were recorded binocularly using E and E. 5-way ANOVAs were applied to investigate the following factors on mfERG: i) ELECTRODE, ii) DILATATION, iii) AGE, iv) EYE, and v) ECCENTRICITY. For mfPERG, the same factors, except dilatation, were investigated applying 4-way ANOVAs. These were conducted for amplitude and peak time of different components as well as signal-to-noise-ratio (SNR).

RESULTS

Amplitudes of mfERG [mfPERG]-based E recording were reduced to 32-38% [37-38%] compared to E, . This corresponded to SNR reduction to 80% [60%], . E based responses had shorter peak times, by 0.2-0.5 ms for N1 and P1, , [P1: 1.5 ms, ]. Both age groups had comparable amplitudes and SNRs, but Young had shorter peak times, by 1.5-2.2 ms for N1 and P1, [3.7-4.2 ms for N1, P1, N2, ]. Compared to dilated recordings, undilated mfERG amplitudes were reduced to 47-87%, , and peak times were delayed by 2.0-11.8 ms, .

CONCLUSIONS

mfPERG & mfERG traces were similar for E and E. However, for skin electrodes, amplitudes and SNRs were lower and peak times shorter. E thus seem to be a viable alternative in patients in whom the use of corneal electrodes is precluded, e.g., children and disabled patients, but at the expense of SNR and with reference to E normative data.