Pattern electroretinogram changes in patients with primary open-angle glaucoma in correlation with visual field and optical coherence tomography changes

Bilateral Pattern Electroretinogram Abnormalities in Patients with Herpes Zoster Keratitis and Conjunctivitis

INTRODUCTION

Herpes zoster ophthalmicus (HZO) results from the reactivation of varicella zoster virus (VZV) in the ophthalmic branch of the trigeminal nerve. The inflammation caused by VZV involves multiple tissues in the eyes. Our goal is to evaluate pattern electroretinogram (PERG) changes and their relationship with corneal sub-basal nerve changes in patients with HZO.

METHODS

Twenty-two patients with herpes zoster keratitis or conjunctivitis and 20 healthy volunteers were recruited for this cross-sectional study. A PERG test was performed on both eyes of HZO patients and one eye of the healthy controls. In vivo confocal microscopy (IVCM) was also performed on both eyes of the HZO patients to detect corneal nerve damage.

RESULTS

Our results showed changes in the PERG parameters in both eyes of HZO patients compared to the healthy controls. Affected eyes showed delayed N95 peak time and decreased P50 and N95 amplitude compared to the unaffected eyes (p < 0.05, respectively). Both affected and unaffected eyes in HZO patients showed delayed P50 peak time and decreased N95 amplitude (p < 0.05, respectively) compared to controls. In HZO patients, no significant differences in each PERG parameter were found between eyes with and without corneal lesions or between eyes with and without increased Langham's cells in the corneal epithelial sub-basal layer. The IVCM images showed decreased total nerve length and number at the sub-basal layer of the epithelial cornea in affected eyes compared to unaffected eyes (p < 0.05). No significant correlation was found between total nerve length and PERG changes.

CONCLUSIONS

Our results showed that VZV-affected eyes without central cornea involvement displayed reduced N95 amplitude and prolonged P50 peak time in bilateral eyes compared to the healthy controls. Larger studies are needed to further explore the effect of HZO on the electrophysiological response of the eye and the posterior segment.

Pattern Electroretinogram in Ocular Hypertension, Glaucoma Suspect and Early Manifest Glaucoma Eyes: A Systematic Review and Meta-analysis

Topic

To provide standardized confidence limits of the transient pattern electroretinogram (tPERG) P50 and N95 and steady state pattern electroretinogram (ssPERG) amplitudes in normal controls as compared to ocular hypertension (OHT), glaucoma suspect (GS), or early manifest glaucoma (EMG) eyes.

Clinical Relevance

The identification of standardized confidence limits in the context of pattern electroretinogram (PERG) might overcome the high intrinsic variability of the measure, and it might lead to a more intuitive understanding of the results as well as to an easier comparison of data from multiple tests, sites, and operators.

Methods

The study protocol was prospectively registered on the International Prospective Register of Systematic Reviews (ID: CRD42022370032). A literature search was conducted on PubMed, Web of Science, and Scopus. Studies comparing PERG raw data in normal control eyes as compared to OHT, GS, or EMG were included. The risk of bias was assessed using the National Institute for Health and Clinical Excellence quality assessment tool. The main outcome was the P50, N95, and ssPERG amplitude difference between the control and the study groups' eyes. The standardized mean difference was calculated as a measure of the effect size for the primary outcome. A subanalysis was conducted based on the type of electrodes adopted for the PERG measurements (invasive vs. noninvasive).

Results

Of the 4580 eligible papers, only 23 were included (1754 eyes). Statistically significant amplitude differences were found in the P50, N95, and ssPERG amplitudes between normal controls and OHT, GS, and EMG eyes. The highest standardized mean difference values were observed in the ssPERG amplitude in all 3 sets of comparison. The subanalysis did not reveal any statistically significant differences between invasive and noninvasive recording strategies.

Conclusions

The use of standardized values as the main outcome measures in the context of the PERG data analysis is a valid approach, normalizing several confounding factors which have affected the clinical utility of PERG both for individual patients and in clinical trials. Steady state PERG apparently better discriminates diseased eyes compared to tPERG. The adoption of skin-active electrodes is able to adequately discriminate between healthy and diseased statuses.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Primary Open Angle Glaucoma Diagnosis Using Pattern Electroretinogram Parameters

Background

Glaucoma is the most typical cause of permanent blindness. POAG, or primary open angle glaucoma, is the most common type. The pattern electroretinogram (PERG) has become a promising technique for detecting glaucoma early-on. The goal of this study was to assess the ability of PERG to diagnose POAG, especially in early, difficult-to-diagnose cases in comparison with other already established diagnostic methods.

Methods

150 participants (300 eyes) were enrolled in a cross-sectional study at ophthalmology department at Menoufia University Hospital in August 2022 to February 2023. All recruited participants underwent comprehensive ophthalmological and PERG exams. The studied eyes were divided into three groups as 100 normal eyes (Group I), 100 eyes with preperimetric glaucoma (Group II), and 100 eyes with established perimetric glaucoma (Group III).

Results

OCT-RNFL average thickness had a significant positive correlation with P50 latency (r=0.289, p=0.041) or P50 amplitude (r=0.302, p=0.018) and N95 amplitude (r=0.640, p=0.001) among group (II). Also, RNFL thickness had negative correlation with P50 amplitude (r= -0.268, p=0.043) among group (III). RNFL thickness and P50 and N95 amplitude showed highest AUC values in detecting preperimetric glaucomatous eyes vs normal eyes (AUC=0.927, 0.952, 904), and for detecting established perimetric glaucomatous eyes vs normal eyes (AUC=1.00, 0.957, 0.983 respectively) compared with VF MD which showed AUC (0.458 and 0.901 respectively).

Conclusion

Glaucoma patients exhibit PERG alterations (comparable to RNFL thickness changes) so, it could be used as an accurate diagnostic method in POAG. Because PERG alterations occur before visual field abnormalities, it could be relied on as an early diagnostic tool in preperimetric glaucoma. We can use both RNFL thickness assessment by OCT with PERG parameters as complementary tests for accurate diagnosis of preperimetric glaucoma which represents the most difficult diagnostic challenge in glaucoma diagnosis.

Monitoring for glaucoma progression with SAP, electroretinography (PERG and PhNR) and OCT

Purpose

To investigate the value of pattern electroretinography (PERG) and photopic negative response (PhNR) in monitoring glaucoma compared to standard clinical tests (standard automated perimetry (SAP) and clinical optic disc assessment) and structural measurements using spectral-domain OCT.

Methods

A prospective study included 32 subjects (32 eyes) with ocular hypertension, suspect or early glaucoma monitored for progression with clinical examination, SAP, PERG, PhNR and OCT for at least 4 years. Progression was defined clinically by the documented change of the optic disc and/or significant visual field progression (EyeSuite™ trend analysis). One eye per patient was included in the analysis.

Results

During the follow-up, 13 eyes (40.6%) showed progression, whereas 19 remained stable. In the progressing group, all parameters showed significant worsening over time, except for the PhNR, whereas in the stable group only the OCT parameters showed a significant decrease at the last visit. The trend of change over time using linear regression was steepest for the OCT parameters. At baseline, only the ganglion cell complex (GCC) and peripapillary retinal nerve fibre (pRNFL) thicknesses significantly discriminated between the stable and progressing eyes with the area under the ROC curve of 0.72 and 0.71, respectively. The inter-session variability for the first two visits in the stable group was lower for OCT (% limits of agreement within ± 17.4% of the mean for pRNFL and ± 3.6% for the GCC thicknesses) than for ERG measures (within ± 35.9% of the mean for PERG N95 and ± 59.9% for PhNR). The coefficient of variation for repeated measurements in the stable group was 11.9% for PERG N95 and 23.6% for the PhNR, while it was considerably lower for all OCT measures (5.6% for pRNFL and 1.7% for GCC thicknesses).

Conclusions

Although PERG and PhNR are sensitive for early detection of glaucomatous damage, they have limited usefulness in monitoring glaucoma progression in clinical practice, mainly due to high inter-session variability. On the contrary, OCT measures show low inter-session variability and might have a predicting value for early discrimination of progressing cases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10633-021-09854-8.

Relationship between N95 Amplitude of Pattern Electroretinogram and Optical Coherence Tomography Angiography in Open-Angle Glaucoma

Purpose: The pattern electroretinogram (PERG) is useful to detect retinal ganglion cell (RGC) damage in patients with glaucoma. Optical coherence tomography angiography (OCTA) measures retinal vessel density (VD), which is known to be reduced in glaucoma. There may be correlations between parameters of the PERG and OCTA in open-angle glaucoma (OAG). Methods: In total, 95 eyes of 95 OAG patients and 102 eyes of 102 normal controls were included in this study. N35, P50, and N95 latency along with P50 and N95 amplitude were obtained using the PERG. Retinal VD was measured around the peripapillary and macular area according to the ETDRS grid (concentric circles with diameters of 1, 3, and 6 mm), which is named a center (≤1 mm), an inner (1–3 mm), an outer (3–6 mm), and a full (≤6 mm) area. Pearson correlation analysis was done between parameters, and partial correlation analysis was done after adjusting confounding factors. Results: P50 amplitude, N95 amplitude, and VD of most measured areas were significantly lower in the OAG group compared to the normal group. N95 amplitude showed a statistically significant correlation with parameters of optical coherence tomography and visual field, peripapillary outer and full VD, and macular outer and full VD even after adjusting confounding factors. There was no significant correlation between parameters in the normal group. Conclusions: N95 amplitude was associated with structural and functional change including VD reduction in OAG. Microvascular alterations may be associated with dysfunctional changes of RGC recorded by the PERG in OAG.