Enhancing Clinical Full-Field Electroretinograms by Reducing Powerline Noise Using Pre-Amplified Electrodes

This study aimed to evaluate the efficacy of pre-amplified electrodes in mitigating powerline noise interference in clinical full-field electroretinograms (ffERGs). Pre-amplified electrodes can reduce powerline noise by providing an alternate pathway for the dissipation of electromagnetically induced noise. Building upon our previous theoretical and animal research, this investigation sought to validate these findings in a clinical setting.

Twenty-nine normal-sighted subjects participated in the study. Standard ffERGs were obtained using both traditional passive electrodes and pre-amplified electrodes consecutively from the same eye. Signal metrics and repeatability were evaluated by comparing the amplitudes and peak times of a-wave and b-wave components. Powerline noise was analyzed using frequency spectrum analysis.

The mean amplitudes and peak times of a-wave and b-wave components between the pre-amplified and passive electrodes showed no statistically significant differences (P > 0.05). Intrasubject variability was modestly reduced when using pre-amplified electrodes, as indicated by lower intra-subject standard deviation (P < 0.04). Powerline noise, measured using signal-to-noise ratio, was significantly diminished in signals from pre-amplified electrodes (P < 0.01, Cohen's D > 2.25) in flash stimulation setups.

Whereas the intrasubject variability improvements in the normally sighted subjects were modest, the improvements in the signal to noise ratio suggest that effective mitigation of powerline noise are possible with pre-amplified electrodes in diseased subjects with reduced ERG amplitudes.

A pre-amplified electrode can reliably and robustly reduce powerline noise and thus improve signal repeatability while preserving signal integrity in clinical ffERGs.