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Comparison between broadband and monochromatic photopic negative response in full-field electroretinogram in controls and subjects with primary open-angle glaucoma
摘要： Purpose A prospective, cross-sectional, case–control study was conducted to investigate the role of broadband and monochromatic photopic negative response (PhNR) of the full-field flash electroretinogram (ERG) in the evaluation of ganglion cell damage in primary open-angle glaucoma (POAG) subjects. Methods Subjects with POAG and age-matched normal subjects were recruited from the outpatient department of a tertiary eye care center in South India. A total of 25 patients with POAG and 50 age-matched normal subjects were recruited. ERG was recorded using broadband (3.5 cd.s/m2 white stimulus on 10 cd/m2 white background) and monochromatic (3.5 cd.s/m2 red stimulus on 10 cd/m2 blue background and 1 cd.s/m2 blue stimulus on 10 cd/m2 yellow background) stimuli. Results The reduction in PhNR amplitude in POAG compared to normal individuals was higher in red-on-blue PhNR [26.37 μV; p < 0.001, confidence interval (CI) 19.34 to 33.4] as compared to broadband stimuli (16.41 μV; p < 0.001, CI 8.68 to 24.13), and blue on yellow (21.96 μV; p < 0.001, CI 10.12 to 33.8). Red-on-blue PhNR amplitudes correlated better with mean deviation (MD; r = -0.66, p < 0.05), pattern standard deviation (PSD; r = -0.4, p = 0.04), visual field index (VFI; r = -0.58, p < 0.05), and retinal nerve fiber layer thickness (r = -0.67, p < 0.05) in comparison with broadband and monochromatic blue-on-yellow PhNR. Receiver operating characteristic curve revealed largest area under the curve (0.89) in red-on-blue PhNR compared to broadband (0.76) and blue on yellow (0.74). The sensitivity and specificity was also higher in red-on-blue PhNR (72% and 80%, respectively) as compared to the other stimuli (sensitivity and specificity of broadband 0.68 and 0.7, blue on yellow 0.64 and 0.7, respectively). Conclusion Correlation of PhNR with Humphrey visual field parameters and retinal nerve fiber layer thickness showed that red-on-blue PhNR can be a useful additional tool for clinical assessment of retinal ganglion cell dysfunction in glaucoma patients. Red-on-blue PhNR was more sensitive as compared to white-on-white and blue-on-yellow PhNR in identifying ganglion cell dysfunction and correlates well with other structural and functional tests for glaucoma such as MD, PSD, VFI, and RNFL thickness.
关键词： Primary open-angle glaucoma,Photopic negative response,Broadband ERG,Full-field electroretinogram,Monochromatic ERG
更新于2025-09-23 15:23:52
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Optimizing a Portable ERG Device for Glaucoma Clinic: The Effect of Interstimulus Frequency on the Photopic Negative Response
摘要： Purpose: The purpose of this study was to investigate the effect of interstimulus frequency on the photopic negative response (PhNR) in the clinical electroretinogram (ERG) in glaucoma and healthy eyes. Methods: Participants with open angle glaucoma (n = 15) and age-matched controls (n = 20) were recruited. Photopic ERGs were recorded in one eye using five frequencies (1–5 Hz) delivered in random order. ERGs were analyzed for changes to amplitude and timing between groups and interstimulus frequency. Coefficient of variation (CoV) was used to examine variability within recordings for each frequency. Results: While the a-wave and b-wave showed minimal alteration, the PhNR was highly sensitive to changes in interstimulus frequency. The PhNR signal was largest at 1 Hz and steadily diminished with higher frequencies in both control and glaucoma groups. Significant differences in PhNR amplitude were found between controls and glaucoma groups at 2 and 3 Hz. While 1 Hz delivered the largest PhNR, it also showed a significantly greater CoV compared to other frequencies. Conclusions: An interstimulus frequency of 2 Hz was optimal for recording the PhNR, creating a good balance between testing time and signal quality. A higher frequency could be used to further shorten clinical testing times; however, this may compromise its clinical utility by dampening the PhNR. Translational Relevance: Here we show the importance of considering flash interstimulus frequency when designing ERG protocols for recording the PhNR as while higher frequencies can shorten test times, they also have considerable effects on the PhNR.
关键词： glaucoma,photopic negative response,electroretinogram
更新于2025-09-23 15:22:29
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A Comparison of the RETeval Sensor Strip and DTL Electrode for Recording the Photopic Negative Response
摘要： Purpose: To compare the RETeval sensor strip and Dawson-Trick-Litzkow (DTL) electrodes for recording the photopic negative response (PhNR) using a portable electroretinogram (ERG) device in eyes with and without glaucoma. Methods: Twenty-six control and 31 glaucoma or glaucoma-suspect participants were recruited. Photopic ERGs were recorded with sensor strip and DTL electrodes in random order using the LKC RETeval device. Stimuli consisted of brief, red flashes (1.7 cd.s/m2) on a blue background (photopic 10 cd/m2). The PhNR amplitude was measured from baseline to trough and also expressed as a ratio over the b-wave amplitude. Results: The sensor strip-recorded PhNR amplitude was significantly attenuated (mean 6 standard deviation [SD], 4.8 6 2.1 vs. 12.7 6 4.8 lV, P , 0.0001), with lower signal-to-noise ratio (SNR; 5.5 6 2.1 vs. 8.1 6 3.9, P , 0.0001), and a trend toward a larger PhNR/b-wave ratio compared with DTL electrodes. The PhNR amplitude, implicit time and PhNR/b-wave ratio correlated with visual field mean light sensitivity, although this fell short of significance for the sensor strip recorded PhNR amplitude. The electrodes demonstrated similar intersession repeatability with a coefficient of repeatability of 627% and 628% for the DTL and sensor strip, respectively. Conclusions: Sensor strip electrodes are a viable alternative for recording reproducible PhNRs, especially when values are normalized to the b-wave. However, DTL electrodes should be considered in cases of attenuated PhNR, or in elevated noise levels, due to its better signal-to-noise quality. Translational Relevance: Sensor strip electrodes can simplify PhNR recordings in the clinic, potentially eliminating the need for an experienced operator.
关键词： electroretinography,PhNR,photopic negative response
更新于2025-09-23 15:22:29
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Baseline Detrending for the Photopic Negative Response
摘要： Purpose: The photopic negative response (PhNR) of the light-adapted electroretinogram (ERG) holds promise as an objective marker of retinal ganglion cell function. We compared baseline detrending methods to improve PhNR repeatability without compromising its diagnostic ability in glaucoma. Methods: Photopic ERGs were recorded in 20 glaucoma and 18 age-matched control participants. A total of 50 brief, red-flashes (1.6 cd.s/m2) on a blue background (10 photopic cd/m2) were delivered using the RETeval device. Detrending methods compared were: (1) increasing the high-pass filter from 1 to 10 Hz and (2) estimating and removing the trend with an increasing polynomial (order from 1–10) applied to the prestimulus interval, prestimulus and postsignal interval, or the whole ERG signal. Coefficient of repeatability (COR%), unpaired Student’s t-test, and area under the receiver operating characteristic curve (AUC) were used to compare the detrending methods. Results: Most detrending methods improved PhNR test–retest repeatability compared to the International Society for Clinical Electrophysiology of Vision (ISCEV) recommended 0.3 to 300 Hz band-pass filter (COR% 6 200%). In particular, detrending with a polynomial (order 3) applied to the whole signal performed the best (COR% 6 44%) while achieving similar diagnostic ability as ISCEV band-pass (AUC 0.74 vs. 0.75, respectively). However, over-correcting with higher orders of processing can cause waveform distortion and reduce diagnostic ability. Conclusions: Baseline detrending can improve the PhNR repeatability without compromising its clinical use in glaucoma. Further studies exploring more complex processing methods are encouraged. Translational Relevance: Baseline detrending can significantly improve the quality of the PhNR.
关键词： electroretinogram,baseline detrending,glaucoma,photopic negative response
更新于2025-09-23 15:22:29
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Functional Loss of the Inner Retina in Childhood Optic Gliomas Detected by Photopic Negative Response
摘要： To determine whether the Ganzfeld ERG photopic negative response (PhNR), an assay of inner retinal activity, is altered in childhood optic glioma (OPG). Seventeen pediatric patients with a diagnosis of OPG, established on neuro-ophthalmologic and brain/orbit magnetic resonance imaging (MRI) criteria, were enrolled. The examination protocol included determination of visual acuity (VA), fundus examination, retinal nerve fiber layer (RNFL) measurement with spectral-domain optical coherence tomography (SD-OCT) and photopic ERG. Fifteen normal children served as control group. Ten of the 17 OPG patients were retested 1 to 3 months after the first examination. Photopic ERGs were recorded after 10 minutes of light adaptation in response to a Ganzfeld flash presented on a steady light–adapting background. Amplitude and peak-time of b-wave and PhNR were measured. Compared with normal values, PhNR amplitude was significantly reduced (P < 0.0001) in the OPG group. Peak-time of PhNR as well as b-wave amplitude and peak-time were similar in both patients and controls. Losses of PhNR were found in patients with involvement of either anterior or retro-chiasmatic optic pathways. Linear regression analysis showed significant positive correlation between RNFL thickness and PhNR amplitude (r2 ? 0.34, P ? 0.008). Mean percentage test–retest difference for PhNR amplitude and peak-time was 12% and 6%, respectively. These findings indicate that flash ERG PhNR can detect a loss of inner retinal function in childhood OPGs supporting the use of this technique, as an adjunct to standard psychophysical and electrophysiological tests, to monitor visual function in OPG.
关键词： photopic negative response,optical coherence tomography,ganglion cells,optic pathways glioma,neurofibromatosis
更新于2025-09-10 09:29:36