Abstract
Purpose :
The photopic negative response (PhNR) of the full-field electroretinogram can be elicited with a red flash on a blue background (RoB), which is the preferred method, and with a white flash on a white background (e.g. standard Light-adapted 3.0 ERG (LA3)), or with a red flash on a white background (RoW), though the latter method is rarely used. However, it is unclear how the pre-stimulus noise would affect the PhNR recordability under various stimulating conditions, and therefore, the purpose of this study was to compare the effect of pre-stimulus noise on PhNR under the three recording conditions.
Methods :
A retrospective chart review and data analysis of patients aged 18 and over undergoing routine ERG testing at the University of South Florida Eye Institute (Tampa, FL) between July 2018 and October 2021 were conducted. Throughout the study period, LA3 and RoW were recorded in the same way while RoB was generated in three different ways as described previously (IOVS 2022;63(7):4540-F0327), resulting in three comparison groups (Gr1, Gr2, Gr3). The level of background bioelectrical activity (30 ms before the flash) was compared between LA3, RoB, and RoW by calculating the root mean square (RMS) of the signal and using Wilcoxon test.
Results :
The records of 74 patients/147 eyes (19M, 55F, mean age 50.5 ± 14.8 years) were evaluated (Gr1=13; Gr2=29; Gr3=32). The RMS of the pre-stimulus signal was significantly higher for the aggregated RoB data compared to either LA3 or RoW data for both the right (OD) and left (OS) eyes (p<0.05, Fig 1). This was reflected also in PhNR recordability, where pre-stimulus noise was higher in signals with non-recordable PhNR vs. signals with recordable PhNR under RoB (OD and OS, p<0.01), as well under LA3 OS (p<0.05), while there was no significant difference under LA3 OD or RoW OD and OS (Fig 2).
Conclusions :
The pre-stimulus noise was lower under RoW and LA3 compared to RoB, suggestive of less facial muscle activity and potentially greater patient comfort. Also, the level of the pre-stimulus noise affected PhNR recordability. Our study suggests that using RoW or LA3 may improve patient comfort and generate a better-quality signal, allowing for a more precise evaluation of PhNR.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.