Pattern Reversal Visual Evoked Potentials Research Articles

Optic nerve involvement in patients with Lyme neuroborreliosis: an electrophysiological study.

The aim of this neurophysiological study was to retrospectively analyze visual evoked potentials (VEPs) acquired during an examination for diagnosing optic nerve involvement in patients with Lyme neuroborreliosis (LNB). Attention was focused on LNB patients with peripheral facial palsy (PFP) and optic nerve involvement. A total of 241 Czech patients were classified as having probable/definite LNB (193/48); of these, 57 were younger than 40 years, with a median age of 26.3 years, and 184 were older than 40 years, with a median age of 58.8 years. All patients underwent pattern-reversal (PVEP) and motion-onset (MVEP) VEP examinations. Abnormal VEP results were observed in 150/241 patients and were noted more often in patients over 40 years (p = 0.008). Muscle/joint problems and paresthesia were observed to be significantly more common in patients older than 40 years (p = 0.002, p = 0.030), in contrast to headache and decreased visual acuity, which were seen more often in patients younger than 40 years (p = 0.001, p = 0.033). Peripheral facial palsy was diagnosed in 26/241 LNB patients. Among patients with PFP, VEP peak times above the laboratory limit was observed in 22 (84.6%) individuals. Monitoring of patients with PFP and pathological VEP showed that the adjustment of visual system function occurred in half of the patients in one to more years, in contrast to faster recovery from peripheral facial palsy within months in most patients. In LNB patients, VEP helps to increase sensitivity of an early diagnostic process.

The Effect of Ethambutol Therapy in terms of Visual Evoked Potential, Color Vision Test, and Contrast Sensitivity Test at the Subclinical Level

Abstract
 Introduction & Objectives : Ethambutol is one of the first-line drugs in the treatment of tuberculosis and known to induce optic neuropathy. However, there are unknown protocols for detecting subclinical level of toxicity. The aim of this study was to assess the difference in amplitude and latency of visual evoked potential (VEP), color vision, and contrast sensitivity in tuberculosis patients before and after taking ethambutol for 1 and 2 months.
 Methods : This was a prospective observational cohort study of 38 eyes of 19 newly diagnosed patients with category-1 tuberculosis being treated with ethambutol. All patients were given ethambutol for 2 months at a dose of 15 - 20 mg/kg body weight/day. The participants underwent complete eye and visual function examination including pattern-reversal VEP, color vision with Farnsworth Munsell D-15 test, and contrast sensitivity with LEA Low Contrast Flip Chart before and after 1 and 2 months of treatment. Wilcoxon test was employed for data analysis.
 Results : During the study, no changes in visual acuity was observed. The results showed that the latencies of VEP after 1 month (p = 0.000) and 2 months (p = 0.000) of treatment were significantly delayed. There was a significant difference in contrast sensitivity after 2 months (p = 0.014) of treatment. However, no significant difference was found in color vision and amplitude of VEP.
 Conclusion : Latency of VEP and contrast sensitivity test could prove useful in detecting subclinical and hence very useful for monitoring patients under ethambutol therapy for ocular toxicity.

Relationship between pattern reversal visual evoked potential P100 wave latency and dysfunctional HDL in patients with multiple sclerosis subjected to an optic neuritis attack: A case-control study.

Optic neuritis frequently occurs during the clinical course of multiple sclerosis (MS). In this condition, demyelination of the optic nerve occurs, which electrophysiologically causes a delay in P100 wave latency. Sensitive cholesterol homeostasis is critical for the formation of the myelin sheath and for myelin to become functionally mature. High-density lipoprotein (HDL) becomes dysfunctional under oxidative stress and plays an important role in the pathogenesis of MS. In this study, HDL levels of MS patients suffering from optic neuritis were compared with those of healthy individuals, and the relationship between pattern reversal visual evoked potential (PRVEP) P100 wave latency and HDL levels in patients with optic neuritis attacks was analyzed. PRVEP studies were performed in patients with MS who had an episode of optic neuritis, and P100 wave latencies were measured. Peripheral blood samples were collected from healthy participants and patients. Lipid levels and myeloperoxidase (MPO) and paraoxonase (PON) activities were measured, and the MPO/PON ratio was then calculated. The lipid profiles and dysfunctional HDL levels in the healthy and patient groups were compared. Finally, the relationship between these parameters and the PRVEP-P100 wave latency was examined. Total cholesterol and low-density lipoprotein (LDL) levels were significantly higher in the patient group (P = .044; P = .038, respectively). There was no statistically significant difference in HDL levels between groups (P = .659). The distribution of MPO values was similar between groups (P = .452). PON values were significantly lower, whereas the MPO/PON ratios were significantly higher in the patient group than in the control group (P = .025; P = .028, respectively). A statistically significant positive correlation was found between the elevated MPO/PON ratio, representing dysfunctional HDL, and both the mean and maximum PRVEP-P100 wave latencies (P < .001, R = 0.690; P < .001, R = 0.815, respectively). A dysfunctional form of HDL may lead to poor deactivation of remyelination-limiting factors and may ultimately be associated with poor outcomes in optic neuritis.

A comparison of visual electrophysiology measures in optic neuropathy

Aims/Purpose: Our aim is to explore the inter‐relationship of clinical PVEP and PERG measurements with each other and the optic nerve structure in children investigated for possible optic neuropathies.Methods: ISCEV Standard PVEPs and PERGs to 50′ check widths to large 30 and standard 15 degree fields were reviewed from children suspected to have optic neuropathy of various pathology. Amplitudes and peak times of PERG P50, N95, the N95:P50 amplitude ratio, the amplitude of the N95 from baseline and at 30 ms from the P50‐N95 slope were measured. Spectralis OCT RNFL sector measures and macular ganglion cell volumes were collated.Results: PERG, PVEP with OCT measurements were available for 42 patients, (83 eyes) aged 6‐17 yrs. Those with abnormal PVEPs (33 eyes) had the most severe macular RGC volume loss (mean 0.26 mm3 in 3.45 mm) with mean LogMAR VA 0.52 (range − 0.01 to 1.00). These patients had inherited optic neuropathies, optic neuritis associated with MOGAD and RMMS. In contrast, patients with papilledema, such as associated with IIH, or presenting with headache and reduced vision and full discs had normal PVEPs. Mean VA LogMAR 0.23 (range − 1.0 to 0.9), and mean macular RGC volume 0.45 mm3 in 3.45 mm circle. N95:P50 amplitude ratios ranged from 1.83 to 0.44 in 30 degree fields and 2.16 to 0.36 in 15 degree fields. The N95:P50 amplitude ratios, slope at 30 ms and N95 from baseline correlated with macular RGC volume, but the best PERG discriminator (AUC 0.83) in the large field was the N95 slope measured at 30 ms. RNFL values were confounded by disc oedema in many cases.Conclusions: Pattern reversal VEPs were abnormal in all patients with severe RGC volume loss. The PERG measures correlate with macular RGC volume. RNFL was confounded by disc oedema, but was helpful in highlighting temporal sector thinning in optic neuritis and inherited optic atrophy such as LHOA.

Poster Session II: Alternating orientation of the chromatic pattern VEP improves signal even in the absence of contrast adaptation.

The visual evoked potential (VEP) to chromatic pattern reversal is greatly reduced compared to VEPs to pattern onsets. Chromatic pattern onsets produce large and stereotypical waveforms that reliably differ from standard achromatic pattern reversal VEP waveforms used in clinical applications. Rapid contrast adaptation for sustained chromatic but not transient achromatic mechanisms has been suggested as one explanation for these observations. Here we first examined changes in the magnitude of response during recordings to reversing and onset grating patterns that preferentially modulate the L-M, S, and achromatic pathways. Given the evidence for both chromatic and achromatic orientation-selective mechanisms, we then hypothesized that contrast adaptation may be reduced by changing the orientation of the pattern for each reversal or onset. VEPs were recorded for 60 s with 2 onsets/reversals per second using both fixed and alternating (horizontal/vertical) orientations. FFT amplitudes for 6-second windows did not reveal evidence of adaptation for chromatic or achromatic onsets or reversal patterns over the 60-second recording period. Despite this, alternating pattern orientation increased the signal for all chromatic but not achromatic conditions. Although alternating the orientation for reversals increased the signal, the onset responses were still larger, even for non-alternating orientations. Mechanisms other than contrast adaptation must be invoked to explain the results.

Poster Session I: Comparison of tripolar and traditional electrodes: Waveform morphology.

The waveforms of visual evoked potentials (VEPs) recorded by tripolar electrodes are different from those recorded by traditional electrode arrays. Traditional arrays record potentials using both an active and a reference electrode. The location of this reference will affect the waveform amplitude and shape. Conversely, tripolar electrodes measure the surface Laplacian across three concentric rings housed within a single electrode surface. These differences may influence the morphology of evoked responses. We compared these two modalities by recording pattern-reversal VEPs to two sizes of checkerboard. Visual inspection of the VEPs suggest that the signals recorded by the tripolar system have attenuated higher frequencies and increased latency of the major waveform components. Root-mean-square comparison of the two signal types confirm attenuation at the higher frequencies in the tripolar recording. Additionally, there is a cumulative delay present within both the large and small check conditions, such that each subsequent component recorded by the tripolar electrodes is shifted increasingly later in time compared to the same components recoded by the traditional electrodes. Such latency shifts may be indicative of a difference in the physiological sources that are measured by the two EEG systems.

ISCEV standard pattern reversal VEP development: paediatric reference limits from 649 healthy subjects

PurposeTo establish the extent of agreement for ISCEV standard reference pattern reversal VEPs (prVEPs) acquired at three European centres, to determine any effect of sex, and to establish reference intervals from birth to adolescence.MethodsPrVEPs were recorded from healthy reference infants and children, aged 2 weeks to 16 years, from three centres using closely matched but non-identical protocols. Amplitudes and peak times were modelled with orthogonal quadratic and sigmoidal curves, respectively, and two-sided limits, 2.5th and 97.5th centiles, estimated using nonlinear quantile Bayesian regression. Data were compared by centre and by sex using median quantile confidence intervals. The ‘critical age’, i.e. age at which P100 peak time ceased to shorten, was calculated.ResultsData from the three centres were adequately comparable. Sex differences were not clinically meaningful. The pooled data showed rapid drops in P100 peak time which stabilised by 27 and by 34 weeks for large and small check widths, respectively. Post-critical-age reference limits were 87–115 ms and 96–131 ms for large and small check widths, respectively. Amplitudes varied markedly and reference limits for all ages were 5–57 μV and 3.5–56 μV for large and small check widths, respectively.ConclusionsPrVEP reference data could be combined despite some methodology differences within the tolerances of the ISCEV VEP Standard, supporting the clinical benefit of ISCEV Standards. Comparison with historical data is hampered by lack of minimum reporting guidelines. The reference data presented here could be validated or transformed for use elsewhere.

Exaggerated response to pattern reversal visual evoked potential among migraineurs

Objective Visual evoked potential recording has reported ambiguous results among migraineurs, thus the present study explored the association of check-size and reversal rates on the latency and amplitude of pattern reversal VEP among migraineurs. Method and material Monocular VEP responses for both eyes were recorded in 133 migraineurs and 111 controls. Checkerboard pattern with phase reversal frequency of 0.5, 1, 2 and 4 Hz and check-size of 16 × 16, 32 × 32, 64 × 64 and 128 × 128, i.e. spatial frequency of 0.475, 1.029, 2.056 and 4.112 cycle per degree (cpd) were used to record 100 responses each. Three-minutes gap was given after change of reversal frequency to a higher rate for next cycle of 4 check-size records. Result A linear increase in latencies was observed with decreasing check-size in both groups, but migraineurs had significantly higher latencies at a given reversal rate. Amplitudes A1 and A2 were higher among migraineurs and amplitude A2 showed an inverted ‘U’ shaped trend with maximum amplitude at 32 × 32 check size (1.029 cpd) in both groups, with an exaggerated response among migraineurs. Check-size 32 × 32 i.e. spatial frequency of 1.029 behaves differently than other larger or smaller check-sizes. Conclusion Variable VEP response for different visual stimuli may be due to differential activation of respective retinocortical pathways and cortical areas. The highest amplitude at modest check-size suggests a contributory role of foveal-parafoveal fibres in migraineurs. Exaggerated physiological response to visual stimuli may be responsible for higher amplitudes and prolonged latencies among migraineurs.

Objective detection of visual field defects with multifrequency VEPs.

To correlate multifrequency pattern reversal VEPs in quadrants (QmfrVEPs) with perimetric field losses for objective detection of visual field losses. QmfrVEP measurements were performed using four LED-based checkerboard stimulators to stimulate the four quadrants of the visual field. QmfrVEPs were measured monocularly in 5 normal subjects and in 5 glaucoma patients who showed losses in conventional Octopus perimetry. The pattern reversal frequency varied slightly between the stimulators: (11.92, 12.00, 12.08 and 12.16 reversals/sec). The responses to the different stimuli were identified by discrete Fourier analysis. VEPs were recorded using different electrode configurations, and the recording with the highest signal-to-noise ratio (SNR) was used for further analysis. QmfrVEP responses from the different quadrants can be reliably measured and separated using the 0.08 reversals/sec interstimulus reversal frequency differences. The signal-to-noise ratio in the four quadrants was significantly correlated with the equivalent visual field losses obtained with perimetry (Spearman rank correlation: P < 0.001). In the five glaucoma patients, the SNR was reduced in 15 out of the 16 quadrants with a perimetric defect, in comparison to the results in quadrants of healthy subjects. This confirms the sensitivity of the procedure. QmfrVEP responses can be measured reliably. This pilot study suggests that high SNR values exclude visual field defects and that focal defects can be identified in glaucoma patients. www. gov . NCT00494923.

Patterned edge-illuminated display for clinical examination of visual evoked potentials using simultaneous magnetic resonance imaging

PurposeCommonly used technologies for visual pattern stimulation cannot operate in a magnetic resonance imaging room because they can interfere with the operation of the scanner and are vulnerable to its electromagnetic and magnetic fields. The aim of this single-center prospective observational study was to introduce a novel, structurally uncomplicated, easy-to-maintain, patterned edge-illuminated display (PEID) device for visual pattern-reversal stimulation, compare it with a commonly used cathode ray tube screen, and verify the equivalence of quantitative assays. Materials and methodsThe left and right eyes of 36 healthy participants with undilated pupils were examined on a commercial visual evoked potential (VEP) apparatus and on the PEID device, where pattern-reversal transient VEPs were elicited by checkerboard stimuli with large (0.89°; 0.86°–0.92°) and small (0.21°; 0.20°–0.23°) checks. ResultsThe PEID device demonstrated the required reliability and dynamic characteristics, as well as precise time-locking required for a VEP diagnosis. The results of Deming's correlation analysis showed that both the commercial cathode ray tube monitor and the PEID device produced identical VEP results within the context of experimental uncertainty. The standard deviation of Deming's regression may indicate the uncertainty of the VEPs measured in clinical practice. The Bland-Altman analysis of the mean showed no significant difference in the amplitude and peak time of VEPs measured on the PEID device compared to that of the commercial cathode ray tube monitor. ConclusionsThe presented PEID device meets all the required standards and can be easily installed in various types of commercial magnetic resonance imaging scanners.

Retinal structure and visual pathway function at school age in children born extremely preterm: a population-based study

BackgroundChildren born extremely preterm (gestational age < 28 weeks) show reduced visual function even without any cerebral or ophthalmological neonatal diagnosis. In this study, we aimed to assess the retinal structure with optical coherence tomography (OCT) and visual function with pattern-reversal visual evoked potentials (PR-VEPs) in a geographically defined population-based cohort of school-aged children born extremely preterm. Moreover, we aimed to explore the association between measures of retinal structure and visual pathway function in this cohort.MethodsAll children born extremely preterm from 2006–2011 (n = 65) in Central Norway were invited to participate. Thirty-six children (55%) with a median age of 13 years (range = 10–16) were examined with OCT, OCT-angiography (OCT-A), and PR-VEPs. The foveal avascular zone (FAZ) and circularity, central macular vascular density, and flow were measured on OCT-A images. Central retinal thickness, circumpapillary retinal nerve fibre layer (RNFL) and inner plexiform ganglion cell layer (IPGCL) thickness were measured on OCT images. The N70-P100 peak-to-peak amplitude and N70 and P100 latencies were assessed from PR-VEPs.ResultsParticipants displayed abnormal retinal structure and P100 latencies (≥ 2 SD) compared to reference populations. Moreover, there was a negative correlation between P100 latency in large checks and RNFL (r = -.54, p = .003) and IPGCL (r = -.41, p = .003) thickness. The FAZ was smaller (p = .003), macular vascular density (p = .006) and flow were higher (p = .004), and RNFL (p = .006) and IPGCL (p = .014) were thinner in participants with ROP (n = 7).ConclusionChildren born extremely preterm without preterm brain injury sequelae have signs of persistent immaturity of retinal vasculature and neuroretinal layers. Thinner neuroretinal layers are associated with delayed P100 latency, prompting further exploration of the visual pathway development in preterms.

A feasibility study for objective evaluation of visual acuity based on pattern-reversal visual evoked potentials and other related visual parameters with machine learning algorithm

BackgroundTo develop machine learning models for objectively evaluating visual acuity (VA) based on pattern-reversal visual evoked potentials (PRVEPs) and other related visual parameters.MethodsTwenty-four volunteers were recruited and forty-eight eyes were divided into four groups of 1.0, 0.8, 0.6, and 0.4 (decimal vision). The relationship between VA, peak time, or amplitude of P100 recorded at 5.7°, 2.6°, 1°, 34′, 15′, and 7′ check sizes were analyzed using repeated-measures analysis of variance. Correlations between VA and P100, contrast sensitivity (CS), refractive error, wavefront aberrations, and visual field were analyzed by rank correlation. Based on meaningful P100 peak time, P100 amplitude, and other related visual parameters, four machine learning algorithms and an ensemble classification algorithm were used to construct objective assessment models for VA. Receiver operating characteristic (ROC) curves were used to compare the efficacy of different models by repeated sampling comparisons and ten-fold cross-validation.ResultsThe main effects of P100 peak time and amplitude between different VA and check sizes were statistically significant (all P < 0.05). Except amplitude at 2.6° and 5.7°, VA was negatively correlated with peak time and positively correlated with amplitude. The peak time initially shortened with increasing check size and gradually lengthened after the minimum value was reached at 1°. At the 1° check size, there were statistically significant differences when comparing the peak times between the vision groups with each other (all P < 0.05), and the amplitudes of the vision reduction groups were significantly lower than that of the 1.0 vision group (all P < 0.01). The correlations between peak time, amplitude, and visual acuity were all highest at 1° (rs = − 0.740, 0.438). VA positively correlated with CS and spherical equivalent (all P < 0.001). There was a negative correlation between VA and coma aberrations (P < 0.05). For different binarization classifications of VA, the classifier models with the best assessment efficacy all had the mean area under the ROC curves (AUC) above 0.95 for 500 replicate samples and above 0.84 for ten-fold cross-validation.ConclusionsMachine learning models established by meaning visual parameters related to visual acuity can assist in the objective evaluation of VA.

The integrity of psychophysical visual function in non-immunocompromised PLHIV (NIPLHIV) without retinitis on antiretroviral therapy (ART).

The present study investigated the integrity of contrast sensitivity (CS), colour vision, and pattern evoked vision potentials (VEP) in non-immunocompromised people living with HIV (NIPLHIV) without retinitis. All participants were visually asymptomatic and no history of ocular disorders, with CD4 counts above 350 cells/mm3, low viral loads and on ART. Thirty NIPLHIV and 30 age-matched HIV negative control groups underwent F100 hue colour assessment, Pelli-Robson contrast sensitivity assessment and pattern-reversal VEP. The median F100 total error scores for NIPLHIV and controls was 33 (IQR: 28;41) and 28 (IQR: 26;48.50) respectively, this was statistically different (p= 0.020). The median P100 amplitude for NIPLHIV was 5.75 µV (IQR: 4.4;8.85) and 4.05 µV (IQR: 3.2;5.8) for controls, this was statistically different (p=0.045). The mean LogCS score 1.83±0.14 and the median P100 peak latency was 105.45 msec (IQR: 102.98;108.98) for NIPLHIV. Higher CD4+ counts were significantly associated with having higher F100 total error scores (OR=0.995; p=0.018), lower P100 amplitudes (OR=1.007; p=0.010) and higher P100 latencies (OR=0.994; p=0.011). Contrast sensitivity function, colour vision, and VEP were uncompromised in NIPLHIV. Associations between CD4 counts with F100 total error scores and P100 latency may aid in the surveillance of vision of NIPLHIV.

In childhood, a different electrode placement improves the recording of pattern reversal visual evoked potentials.

In childhood, a different electrode placement improves the recording of pattern reversal visual evoked potentials.

Impact of keratoprosthesis implantation on retinal and visual pathway function assessed by electrophysiological testing.

To investigate the impact of Boston Type I Keratoprosthesis (BI-Kpro) implantation on retinal and visual pathway function, respectively, assessed by full-field electroretinography (ERG) and visually evoked potentials (VEPs). This is a prospective interventional longitudinal study, and patients with BI-Kpro implantation were assessed preoperatively and at 3 and 12months after surgery. ERG, flash, and pattern-reversal VEPs (15' and 60' checks) along with visual acuity (VA) were performed. A total of 13 patients (24 to 88years of age) were included. Mean baseline VA (logMAR) improved from 2.30 to 1.04 at 3months and to 1.00 at 12months. Flash VEPs were normal in 6 (46%) patients and in 10 (77%) patients at the 12-month follow-up. PVEP was non-detectable in all patients preoperatively for both check sizes. For 15' check size, 6 (46%) patients showed responses after 3 and 12months except for 1 patient with normal responses at 12months with the remaining non-detectable. For 60' checks, 11 (85%) patients had responses 3months after surgery with only 9 (70%) showing responses at 12months. Abnormal full-field ERGs were found in all patients preoperatively. Amplitude improvement was found in 10 (77%) patients from baseline to 3months and in 8 (62%) patients from the 3- to the 12-month follow-up. In this small cohort of patients with BI-Kpro implantation, a remarkable improvement on visual function quantitatively assessed by electrophysiological testing was found in the majority of cases. Visual electrophysiological testing can contribute to objectively assess functional outcomes in this population.

Spheno-Orbital Meningioma and Vision Impairment—Case Report and Review of the Literature

(1) Background: Spheno-orbital meningioma (SOM) is a very rare subtype of meningioma which arises from the sphenoid ridge with an orbital extension. It exhibits intraosseous tumor growth with hyperostosis and a widespread soft-tissue growth at the dura. The intra-orbital invasion results in painless proptosis and slowly progressing visual impairment. (2) Methods: We present a case of a 46-year-old woman with SOM and compressive optic nerve neuropathy related to it. Her corrected distance visual acuity (CDVA) was decreased to 20/100, she had extensive visual field (VF) scotoma, dyschromatopsia, impaired pattern-reversal visual-evoked potential (PVEP), and decreased thicknesses of the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC), measured with the swept-source optical coherence tomography (SS-OCT), and a pale optic nerve disc in her left eye. Brain CT and MRI showed a lesion at the base of the anterior cranial fossa, involving the sphenoid wing and orbit. Pterional craniotomy and a partial removal of the tumor at the base of the skull and in the left orbit with the resection of the lesional dura mater and bony defect reconstruction were performed. (3) Results: The histological examination revealed meningothelial meningioma (WHO G1). Decreased CDVA and VF defects completely recovered, and the color vision score and PVEP improved following the surgery, but RNFL and GCC remained impaired. No tumor recurrence was observed at a follow-up of 78 months. (4) Conclusions: Optic nerve dysfunction has the capacity to improve once the compression has been relieved despite the presence of the structural features of optic nerve atrophy.

Effect of Dioptric Blur on Pattern-Reversal and Motion-Onset VEPs as Used in Clinical Research.

To describe the effect of dioptric blur on visual evoked potentials (VEPs) induced by motion onset (MO-VEPs). The effect of dioptric blur up to 4 D on MO-VEPs was tested on 12 subjects using central, peripheral, and full-field stimulation with a low-contrast structure of concentric circles with spatial frequency <1 c/°. The results were compared to VEPs evoked by 15' and 60' checkerboard pattern-reversal (PR-VEPs). The relationship between peak time and interpeak amplitude of the dominant components was related to the level of dioptric blur using linear regression. The MO-VEPs did not show a significant peak prolongation (P > 0.28) or amplitude attenuation (P > 0.14) with the blur, whereas for the PR-VEPs we observed a significant decrease in amplitude (P < 0.001) and increase in peak time (P < 0.001) for both checkerboard sizes. For MO-VEPs induced by radial motion of low contrast and low spatial frequency pattern, the change in retinal blur does not affect the peak time or the interpeak amplitude of the dominant N2 component. The resistance to retinal blur that we demonstrated for MO-VEP provides a diagnostic opportunity to test the integrity of the visual system and reveal a retrobulbar impairment even in uncorrected refractive errors.

Different visual evoked potentials in neuromyelitis optica spectrum disorder-related optic neuritis and idiopathic demyelinating optic neuritis: a prospective longitudinal analysis

BackgroundTo investigate different visual evoked potential (VEP) patterns in neuromyelitis optica spectrum disorder-related optic neuritis (NMOSD-ON) and idiopathic demyelinating optic neuritis (IDON).MethodsThis was a longitudinal, prospective, case-control study. Eighty-four Chinese patients with acute optic neuritis were enrolled, including 26 NMOSD-ON patients and 58 IDON patients. All the patients underwent best-corrected visual acuity (BCVA) and full-field pattern reversal VEP recordings at the onset, 1 month, 3 months, and 6 months.ResultsWithin 15′ checks, the NMOSD-ON patients had more severe VEP amplitude reduction at 6 months (2.39 ± 4.63 μV vs. 6.96 ± 8.88 μV, P = 0.034). However, the IDON patients showed more frequently normal VEP response at 3 months (24.0% vs. 4.5%, P = 0.017), and only prolonged P100 peak latency with normal amplitude (L) at 6 months (30.0% vs. 57.8%, P = 0.048). Within 60′ checks, no significant difference in VEP parameters between the two groups was found at each follow-up (P > 0.05). ConclusionsThe NMOSD-ON patients showed more severe axonal damage and worse axonal recovery than the IDON patients. VEP elicited by smaller check size was more sensitive to visual pathway abnormality in NMOSD-ON.

Long-term effects of methamphetamine abuse on visual evoked potentials.

To compare visual evoked potential (VEP) components in normal individuals and those with long-term methamphetamine and crystal methamphetamine use. In this study, monocular pattern-reversal VEPs were recorded in 40 methamphetamine and crystal methamphetamine users and 38 normal individuals. Visual stimuli were high-contrast (99%) checkerboard patterns at 15 and 60 min of arc with a reversal rate of 1.53 reversals per second. A significant difference was seen between the two groups for the P100 peak time for the 60 min of arc checks (p= 0.002, d= 0.75, 4.61% higher peak time in the addicted group) and the 15 min of arc checks (p= 0.004, d= 0.73, 4.78% higher peak time in the addicted group). However, other VEP components were not significantly different between the two groups. The higher P100 peak time at both 15 and 60 min of arc in methamphetamine-dependent users reveals that VEPs are highly sensitive for the diagnosis of retinal and visual pathway lesions.

Effect of Visual Evoked Potentials in Patients with Primary Hypertension

Hypertension can cause vascular endothelial changes which can lead to hyalinization and demyelination. It also causes hypertensive retinopathy and retinal artery atrophy in chronic hypertensive patients. Retinal artery atrophy can lead to demyelination changes in the optic nerve. Visual evoked potentials (VEPs) can be used as a sensitive method for documenting the abnormalities in the visual pathways. VEPs are electrical potential differences recorded from the scalp to the visual stimuli. The demyelination changes of optic nerve in early stages of primary hypertension were not studied much. Hence, this study was aimed to assess the effect of VEP in primary hypertension. The main objective of this study was to correlate the latency and amplitude of VEPs in normal individuals and primary hypertensive patients. This is a comparative study which was done between two groups. Group A was a control group with 60 normal participants and group B was a study group that had 60 primary hypertensive patients. Pattern reversal VEP (Parameters – N75, P100 &amp; N145 latencies and amplitude of P100) was recorded in both groups. The variables were correlated between group A and group B. In the result of this study, the VEP latencies of N75 and P100 waves was increased (duration delayed) significantly in both right eye and left eye of participants in Group B than Group A. Amplitude of P100 wave was decreased in both eye, but it is not statistically significant in left eye. VEP parameters can be used for routine screening and diagnostic tests for visual impairment and hypertensive retinopathy even in earlier stages of hypertensive patients.