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Pre-stimulus bioelectrical activity in light-adapted ERG under blue versus white background.
Katherine Tsay1, Sara Safari1, Abdullah Abu-Samra1
1Morsani College of Medicine, University of South Florida, Tampa, FL, USA.
Visual Neuroscience
|December 13, 2023
Summary
The white flash on a white background (LA3) full-field electroretinogram (ERG) method produces less pre-stimulus noise than red flash on a blue background (RoB). This suggests LA3 may yield higher quality signals for evaluating retinal ganglion cell function.
Area of Science:
- Ophthalmology
- Neuroscience
- Physiology
Background:
- The photopic negative response (PhNR) is a key electroretinogram (ERG) component for assessing retinal ganglion cell function.
- Two common methods for eliciting PhNR are red flash on a blue background (RoB) and white flash on a white background (LA3).
- Understanding baseline signal characteristics is crucial for accurate PhNR interpretation.
Purpose of the Study:
- To compare baseline signal noise between RoB and LA3 ERG stimulation conditions.
- To determine the impact of pre-stimulus signal levels on the identification of unambiguous PhNR components.
- To evaluate which ERG method may provide a higher quality signal for retinal ganglion cell assessment.
Main Methods:
- Retrospective chart review of four patient cohorts undergoing routine ERG testing.
- Calculation and comparison of the root mean square (RMS) of pre-stimulus bioelectrical activity (30 ms before flash) between RoB and LA3 conditions.
- Statistical analysis using the Wilcoxon test to compare noise levels and their effect on PhNR identifiability.
Main Results:
- Pre-stimulus noise (RMS) was significantly higher under RoB stimulation compared to LA3 in all tested conditions for both eyes (RoB/LA3 RMS ratio: 1.70 and 1.57).
- No significant difference in baseline noise (RMS) was observed across different protocols within either LA3 or RoB conditions.
- Higher pre-stimulus noise correlated with less identifiable PhNR components under RoB, whereas this correlation was less pronounced under LA3.
Conclusions:
- The LA3 method generates less background bioelectrical activity, potentially due to reduced facial muscle interference, leading to a higher quality signal.
- Pre-stimulus noise levels significantly affect the ability to clearly identify the PhNR component.
- LA3 is recommended as a potentially superior or supplementary method for evaluating retinal ganglion cell function via ERG, pending optimization of RoB conditions.
