Abstract
Purpose :
Ample experience in electroretinography (ERG) shows a high correlation between ERG recording methods. In our hands, the measured amplitudes using skin electrodes are about one-third of the amplitudes with contact lens electrodes. In this report, we compare the signal-to-noise ratios (SNR) using skin electrodes and contact lens electrodes.
Methods :
23 patients with normal ERGs and various retinal dystrophies were studied. Full-field ERGs were recorded simultaneously from both eyes with ERG-jet corneal CL electrodes and LKC Technologies Sensor Strip adhesive skin electrodes using multi-channel instrumentation (Diagnosys LLC, Espion3). Photopic 3.0, 30 Hz flicker, Scotopic 0.01, and Scotopic 3.0 ERG responses were analyzed; b-wave amplitude was used as a measure of signal strength. Baseline noise was calculated as the standard deviation of the waveform prior to flash stimulus, between -10 to –1 millisecond. The SNR was compared between corneal CL and skin electrodes using one-sided t-tests with a significance criterion of 0.01.
Results :
The average CL electrode amplitude was 2.77 (p< .00001) times the magnitude of the corresponding skin electrode amplitude. Absolute noise level with skin electrodes was slightly less than the noise level for CL electrodes (5.7 µV vs 7.1 µV, p=0.035).
We found that measured amplitudes varied across ERG responses. CL electrode amplitude compared to skin electrode amplitude was 2.55 (p< .00001) times greater in Photopic 3.0, 2.1 (p =. 000108) times greater in 30 Hz flicker, 2.1 (p < .00001) times greater in Scotopic 0.01, and 2.94 (p < .00001) times greater in Scotopic 3.0 ERG response.
The cumulated SNR using the CL electrode was significantly greater than with skin electrodes (22.4 vs 10.98, p= 0.006); the SNR using CL electrodes was, on average, 2.15 times greater than the SNR using skin electrodes. CL electrode SNL compared to skin electrode SNL was 2.59 (p< .00001) times greater in Photopic 3.0, 2.1 (p =.000037) times greater in 30 Hz flicker, 1.84 (p= .000048) times greater in Scotopic 0.01, and 2.098 (p=.000845) times greater in Scotopic 3.0 ERG response
Conclusions :
Compared to skin electrodes, Corneal CL electrodes have nearly three times greater amplitude and two times greater signal-to-noise ratio.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.