Abstract
Purpose :
The photopic negative response (PhNR) is a component of the full-field electroretinogram (ERG) reflecting the function of the retinal ganglion cells. The current recommendation to optimally elicit the PhNR response is with a red flash stimulus on a blue background (ROB) as defined by the International Society for Clinical Electrophysiology of Vision (ISCEV). The purpose of this study was to compare PhNR and b-wave amplitudes in patients between two conditions: ROB and standard Photopic 3.0 ERG (Ph3) under two different protocols.
Methods :
A retrospective chart review and data analysis of patients aged 18 and over undergoing routine ERG testing at USF Eye Institute (Tampa, FL) between July 2018 and October 2021 was conducted. Throughout the study period, while Ph3 was recorded in the same way, ROB response was generated in two different ways. Group 1’s ROB protocol used a ~2.5 cd.s/m2 red flash (627 nm) on a 10 cd/m2 blue background (470 nm), Group 2 protocol used a 5 cd.s/m2 red flash on a 10 cd/m2 blue background. PhNR was measured before and after the i-wave, as PhNR1 and PhNR2, respectively. Eyes where the average signal did not come from at least 5 individual quality runs or those whose b-wave amplitude responses were less than 10 µV were excluded.
Results :
The records of 55 patients / 110 eyes (13 M, 42 F; mean age 50.1 +/- 14.3 years) were selected: 27 patients (Group 1) and 28 patients (Group 2). There was no significant difference between the linear regression slopes of PhNR amplitudes under Ph3 vs. ROB between left and right eyes for either group (p>0.05), although the slopes in Group 1 were steeper compared to Group 2 (1.0 vs. 0.44). Furthermore, no significant difference was observed between the slopes of PhNR1 vs. PhNR2 in either group (p>0.05), although PhNR2 peaks were less reliably determined compared to PhNR1 (41.7% in Group 1 and 74.5% in Group 2). Similarly, the slopes of the b-wave amplitudes were not significantly different between right and left eyes (p>0.05) and appeared to be no different between Group 1 and Group 2 (p>0.05).
Conclusions :
Consistent and predictable correlations were found between the PhNR responses obtained under Ph3 and ROB recording conditions at two different strengths of ROB stimulation.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.