Applications of Isolated-Check Visual Evoked Potential in Early Stage of Open-Angle Glaucoma Patients

Glaucoma classification through SSVEP derived ON- and OFF-pathway features

Recent evidence from small animal models and human electrophysiology suggests that the OFF-pathway is more vulnerable to glaucomatous insult than the ON-pathway. Thus, OFF-pathway based measurements of visual function may be useful in the diagnosis of Glaucoma. The steady-state visually evoked potential (SSVEP) can be used to non-invasively make such functional measurements. Here, we examine whether OFF- and ON-pathway biasing SSVEP measurements differently predict glaucoma diagnosis using a large cohort of 98 glaucoma patients and 71 controls. Using both a logistic regression with k-fold cross-validation and a random forest classifier, we show that OFF-pathway biasing features produce a small improvement in predictive accuracy over ON-pathway biasing features. However, despite our inclusion of many more response features and the retention of both participants' eyes, our classifier did not perform as well as previous reports that used the isolated-check VEP. This is likely a result of the relatively small amount of data we collected for each participant, but may also be explained by the absence of any train-test splitting in preexisting work. Nevertheless, our results support further exploration of the diagnostic potential of OFF-pathway biasing functional biomarkers for glaucoma.

Early impairment of magnocellular visual pathways mediated by isolated-check visual evoked potentials in primary open-angle glaucoma: a cross-sectional study

OBJECTIVE

To explore different performances in the magnocellular (MC) and parvocellular (PC) visual pathways in patients with primary open-angle glaucoma (POAG) and to objectively assess impairment in early stage of POAG.

METHODS AND ANALYSIS

This is a cross-sectional study. MC and PC visual pathways were assessed using isolated-check visual evoked potential (ic-VEP). Visual acuity, intraocular pressure, fundus examination, optical coherence tomography and visual field were measured. Signal-to-noise ratios (SNRs), mediated by ic-VEP were recorded. The Spearman's correlation analysis was used to estimate the relationships between visual functions and structures. Receiver-operating-characteristic (ROC) curves were used to estimate the accuracy in detection of early POAG.

RESULTS

60 participants (30 early POAG eyes and 30 age-matched control subjects) were recruited. MC visual pathway showed a non-linear response function, while PC visual pathway was a linear response function as contrast increased. Early POAG eyes exhibited significantly weaker initial contrast gains and lower maximum responses in the MC visual pathway (p=0.001, p=0.004, respectively). The SNRs at 8% and 32% depths of modulation (DOM) were significantly correlated with temporal-side retinal nerve fibre layer (RNFL) thickness in early POAG in MC-biased stimulation (p=0.017, p=0.020, respectively). The areas under ROC of 16% DOM were 0.780 (sensitivity 80.0%, specificity 63.3%) with the cut-off SNR of 2.07.

CONCLUSIONS

The MC visual pathway was damaged in the early stage of POAG. The SNRs at 8% and 32% DOM of MC-biased stimulation were significantly correlated with temporal-side RNFL thickness in early POAG, which helped in understanding the mechanisms of visual impairment in the early stage of POAG.

Utility of isolated-check visual evoked potential technique in dysthyroid optic neuropathy

PURPOSE

To analyze the utility of isolated-check visual evoked potential (icVEP) for discriminating between eyes with dysthyroid optic neuropathy (DON) and eyes with thyroid-associated ophthalmopathy (TAO) but not DON.

METHODS

Forty-three eyes with TAO but not DON (as non-DON), fifty-three eyes with DON, and sixty healthy eyes (as controls) were included. Comprehensive ophthalmic examinations, including best-corrected visual acuity, refraction, color vision test, intraocular pressure measurement, slit-lamp biomicroscopy, ophthalmoscopy, RAPD, exophthalmometry measurements, pVEP test, icVEP test, standard automated perimetry, and clinical activity score classification of TAO, as well as demographic information, were collected and analyzed.

RESULTS

In the DON group, the signal-to-noise ratio (SNR) value of icVEPs decreased significantly compared with that of the non-DON group as well as control (p < 0.05). The SNR values under 8%, 16% and 32% depth of modulation (DOM) were significantly negatively correlated with BCVA (p < 0.05, r =  - 0.9 ~  - 0.6), papilledema (Y/N) (p < 0.05, r =  - 0.8 ~ 0.4) and DON (Y/N) (p < 0.001, r =  - 0.7 ~  - 0.5). The 8% DOM of icVEP had the largest area under the receiver operating characteristic curve (AUC) (0.842) for discriminating DON from non-DONs. Meanwhile, decision curve analysis (DCA) showed that patients clinically benefit most from 8% DOM of icVEP. Furthermore, the 8% DOM of icVEP combing with papilledema (Y/N) and BCVA (Model 1) has significantly larger AUC than the 8% DOM of icVEP (p = 0.0364), and has better clinical benefit in DCA analysis.

CONCLUSIONS

The SNR of 8% DOM from icVEP may represent a significant ancillary diagnostic method for DON detection. Furthermore, icVEP combined with papilledema (Y/N) and BCVA should be considered as a diagnostic model in future clinical practice.

Diagnostic Capability of Isolated-Check Visual Evoked Potential for Early to Moderate Primary Open-Angle Glaucoma

This study aimed to evaluate the diagnostic capability of isolated-check visual evoked potential (icVEP) for primary open-angle glaucoma (POAG) via comparison with visual field (VF) tests and pattern visual evoked potential (PVEP). This cross-sectional study enrolled 68 subjects, including 33 POAG patients and 35 controls. All subjects underwent a complete ophthalmic examination, including icVEP, PVEP, and VF tests. The diagnostic performance, the area under the receiver operating characteristic curve (AUC), the integrated discrimination index (IDI), and the net reclassification index (NRI) were calculated. The clinical benefits of the three tests were compared via decision curve analysis (DCA) of the signal-to-noise ratio (SNR) from icVEP, the P100 latency and amplitude of 1° and 0.25° checks from the PVEP, pattern standard deviation (PSD), and mean deviation (MD) from the VF test. The SNR, MD and PSD, PVEP P100 latency of 0.25° checks, and P100 amplitude (both 1° and 0.25° checks) showed significant differences between the POAG and control groups (* p < 0.05), except for the P100 latency of 1° checks. Regarding diagnostic ability, the three tests, AUC, IDI, and NRI, showed no significant difference (p > 0.05). The DCA showed that the clinical benefits of icVEP (SNR) were comparable to those of VF (MD and PSD) and better than those of PVEP (P100 latency and amplitude). In addition, no significant difference was found in the consistency analysis of the qualitative comparison between the icVEP, VF, and PVEP (McNemar p > 0.05). In this study, icVEP showed a diagnostic ability for early to moderate POAG patients comparable to VF and PVEP. IcVEP might be applied as a supplementary psychophysical examination method in addition to VF examinations for special POAG populations who have difficulty cooperating with the VF examination.

Applications of dynamic visual acuity test in clinical ophthalmology

Dynamic visual acuity test (DVAT) plays a key role in the assessment of vestibular function, the visual function of athletes, as well as various ocular diseases. As the visual pathways conducting dynamic and static signals are different, DVATs may have potential advantages over the traditional visual acuity tests commonly used, such as static visual acuity, contrast sensitivity, and static perimetry. Here, we provide a review of commonly applied DVATs and their several uses in clinical ophthalmology. These data indicate that the DVAT has its unique clinical significance in the evaluation of several ocular disorders.

Applications of the isolated-check visual evoked potential in primary open angle glaucoma with or without high myopia

AIM

To explore the diagnostic performance of isolated-check visual evoked potential (icVEP) for primary open angle glaucoma (POAG) in both highly myopic and non-highly myopic populations and compare it with those of optical coherence tomography (OCT) and Heidelberg retinal tomography (HRT) parameters.

METHODS

A total of 126 participants were recruited, including 31 highly myopic participants with POAG (HM-POAG), 36 non-highly myopic participants with POAG (NHM-POAG), 25 highly myopic participants without POAG (HM) and 34 controls without high myopia (Normal). All the participants underwent a complete ophthalmic examination. The signal-to-noise ratio (SNR) was used to assess the icVEP. Both qualitative and quantitative diagnostic performances of OCT, HRT and the icVEP were analyzed and compared.

RESULTS

Based on the criterion of SNR≤1, the diagnostic performance of the icVEP in highly myopic subjects [area under the receiver operating characteristic curve (AUC)=0.862] was better than that in non-highly myopic subjects (AUC=0.789), and the SNR had fairly good specificity. In distinguishing the HM-POAG and HM groups, the AUC of the SNR was not different from those of the OCT and HRT parameters (P>0.05) in either the qualitative or quantitative comparison. In the qualitative analysis, the icVEP showed good consistency with damage to the central 10° of the visual field (kappa=0.695-0.747, P<0.001).

CONCLUSION

The icVEP has the potential to discriminate individuals with and without POAG, especially in populations with high myopia.

Isolated-check visual evoked potential: a more sensitive tool to detect traumatic optic neuropathy after orbital fracture

PURPOSE

To establish a more sensitive diagnostic tool for traumatic optic neuropathy (TON), we explored the diagnostic efficacy of isolated-check visual evoked potential (ic-VEP) for TON in orbital fracture and compared ic-VEP with pattern-reversal visual evoked potential (P-VEP) testing.

METHODS

This was a prospective single-center study. A total of 137 eyes from 131 patients diagnosed between December 2016 and October 2019 with orbital fractures were included in the study. Injury history, best-corrected visual acuity (BCVA), visual field, computed tomography (CT), P-VEP, and ic-VEP data were collected. Parameters of ic-VEP (signal-to-noise ratio [SNR]) and P-VEP (peak latency and amplitude of P100) were compared and diagnostic accuracy was analyzed.

RESULTS

TON was associated with worse BCVA than non-TON (median 0.52 versus 0.10 logMAR, P < 0.001). SNRs were negatively associated with the P100 peak latency while positively associated with the P100 amplitude. The sensitivity of ic-VEP for TON (79.6%) was higher than that of P-VEP (61.2%, P = 0.049), although this difference was not statistically significant after Bonferroni correction. Using ic-VEP and P-VEP together could increase sensitivity (87.8%). Maximum areas under curve were obtained using the SNR criteria of 1.3, 1.47, and 1.54 at 8%, 16%, and 32% depth of modulation, respectively.

CONCLUSION

ic-VEP was more sensitive than P-VEP in diagnosing TON, and a combination of the two examination tests was recommended. The use of ic-VEP as the new diagnostic standard technique for TON should be considered.

Comparing isolated-check visual evoked potential, pattern visual evoked potential, and standard automated perimetry in dysthyroid optic neuropathy eyes

Objective

To determine the diagnostic ability of isolated-check visual evoked potential (icVEP), pattern visual evoked potential (pVEP), and standard automated perimetry (SAP) between dysthyroid optic neuropathy (DON) and thyroid-associated ophthalmopathy (TAO) without DON (non-DON).

Methods

This is a case-control study, 49 bilateral patients (26 DON and 23 non-DON) were included. icVEP, pVEP, and SAP were conducted in all the subjects, icVEP parameters compared were signal-to-noise ratios (SNRs) under 8, 16, and 32% depth of modulation (DOM). pVEP parameters compared were amplitude and latency. SAP parameters were mean deviation (MD) and pattern standard deviation (PSD). The area under the receiver operating characteristic (ROC) curve (AUC), net reclassification index (NRI), integrated discrimination index (IDI), and decision curve analysis (DCA) were applied for analysis.

Results

In icVEP, values of SNR in DON were significantly smaller than non-DON (p < 0.05). In pVEP, P100 latent time in DON was significantly larger than non-DON (p = 0.0026). In SAP, value of PSD in DON was larger than non-DON (p = 0.0006), and value of MD in DON was smaller (p = 0.0007). AUC, NRI, and IDI among the three tests were not significantly different. DCA showed that SNR of icVEP under 8% DOM was the farthest from the two extreme curves.

Conclusions

icVEP, pVEP, and SAP have equal diagnostic capabilities to discern between DON and non-DON. In addition, icVEP may represent a significant ancillary diagnostic approach to DON detection, with more clinical benefit.

Discovery and clinical translation of novel glaucoma biomarkers

Glaucoma and other optic neuropathies are characterized by progressive dysfunction and loss of retinal ganglion cells and their axons. Given the high prevalence of glaucoma-related blindness and the availability of treatment options, improving the diagnosis and precise monitoring of progression in these conditions is paramount. Here we review recent progress in the development of novel biomarkers for glaucoma in the context of disease pathophysiology and we propose future steps for the field, including integration of exploratory biomarker outcomes into prospective therapeutic trials. We anticipate that, when validated, some of the novel glaucoma biomarkers discussed here will prove useful for clinical diagnosis and prediction of progression, as well as monitoring of clinical responses to standard and investigational therapies.

Electrophysiology in Glaucoma

OBJECTIVES

Electrophysiological testing of the visual system has been continuously used in studies involving the evaluation of retinal ganglion cells and the diagnosis of glaucoma. This study aims to review the results of recent studies regarding the clinical applicability of electrophysiological tests to glaucoma.

METHODS

A systematic review of the literature was carried out by 2 independent reviewers using the PubMed and EMBASE electronic databases, searching for articles published in English from January 1, 2014 to July 1, 2019 using a combination of the following keywords: ("glaucoma" OR "ocular hypertension") AND ("electrophysiolog" OR "electroretinogra" OR "ERG" OR "mfERG" OR "Pattern-reversal electroretinography" OR "PERG" OR "mfPERG" OR "photopic negative response" OR "pattern electroretinogram" OR "visual evoked potential" OR "multifocal electroretinography" OR "multifocal electroretinogram" OR "electro-oculography" OR "multifocal VEP" OR "mf-ERG"). A total of 38 studies were selected and the data of 30 of them were tabulated in this review.

RESULTS

Among the 30 studies selected, the photopic negative response and the reversal pattern electroretinogram were found to be the major methods used to record the electroretinographic responses generated by the retinal ganglion cell. Their multifocal versions and the multifocal visual evoked potential were also proposed during this period. In general, the results underscored a consistent but general correlation between the amplitude and latency measures and routine tests for glaucoma, such as perimetry and optical coherence tomography.

DISCUSSION

In agreement with previous reviews, clinical electrophysiological testing of the visual system reasonably matched with both the structural and functional analyses for glaucoma. No definitive indications of these tests have been established either at early detection or during follow-up of the disease, and easier protocols and better topographical correspondence with current glaucoma tests are warranted for their routine use.

Visual evoked potential in the early diagnosis of glaucoma. Literature review

Visual evoked potentials (VEP) are a significant visual electrophysiological diagnostic exam, which can be used as a suitable objective measure of optic nerve function. The topic was greatly debated and many correlations between the magnitude of the VEP latency parameters and parameters of Humphrey static perimetry suggested that the abnormal cortex responses in patients with glaucomatous changes could be tested by both electrophysiological and physical methods. Moreover, the optic nerve glaucomatous damage observed by reduction in ganglion cell layer and retinal fibre layer thickness through SD-OCT tests, which are known to precede Humphrey visual field defects, correlates with VEP latency parameters, thus consolidating the position of the VEP testing in glaucoma progression.