Visual Evoked Potentials Parameters Research Articles

Chronic Inflammatory Demyelinating Polyneuropathy and Evaluation of the Visual Evoked Potentials: A Review of the Literature.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare autoimmune disorder characterised by the progressive demyelination of peripheral nerves, resulting in motor and sensory deficits. While much research has focused on clinical and electrophysiological aspects of CIDP, there is an emerging interest in exploring its impact on the visual system through visual evoked potentials (VEPs). This comprehensive review synthesises existing literature on VEP findings in CIDP patients, shedding light on their potential diagnostic and prognostic value. The review thoroughly examines studies spanning the last two decades, exploring VEP abnormalities in CIDP patients. Notably, VEP studies have consistently revealed prolonged latencies and reduced amplitudes in CIDP patients compared to healthy controls. These alterations in VEP parameters suggest that the demyelinating process extends beyond the peripheral nervous system to affect the central nervous system, particularly the optic nerve and its connections. The correlation between VEP abnormalities and clinical manifestations of CIDP, such as visual impairment and sensory deficits, underscores the clinical relevance of VEP assessment in CIDP management. Furthermore, this review addresses the potential utility of VEPs in aiding CIDP diagnosis and monitoring disease progression. VEP abnormalities may serve as valuable biomarkers for disease activity, helping clinicians make timely therapeutic decisions. Moreover, this review discusses the limitations and challenges associated with VEP assessment in CIDP, including variability in recording techniques and the need for standardised protocols. In conclusion, this review highlights the evolving role of VEPs as a non-invasive tool in CIDP evaluation. The consistent VEP abnormalities observed in CIDP patients suggest the involvement of the central nervous system in this demyelinating disorder. As our understanding of CIDP and its pathophysiology continues to evolve, further research in this area may lead to improved diagnostic accuracy and monitoring strategies, ultimately enhancing the clinical management of CIDP patients.

The effect of different blood groups on visual evoked potentials

Introduction and aim. Purpose of the study is to determine whether it is required to use different standards when evaluating visual evoked potential (VEP) measurements of healthy individuals with different blood groups. Material and methods. The study consisted of healthy individuals with different blood groups who have applied to the ophthalmology and neurology outpatient clinic of Düzce University Medical Faculty from January to December 2022. The patients went through detailed ophthalmologic examination and VEP test and only the ones with normal results were included to the study. Results. The study consisted of 119 individuals, with a blood group distribution of 30 A, 29 B, 30 AB and 30 O. VEP latency and amplitude changes were compared and no significant difference was observed within 4 groups in terms of P100 and N70 latency and amplitudes. There was N70 latency prolongation in Rh- group and this difference was found to be statistically significant (p=0.009). Rh+ group was found to be high in terms of P100 amplitudes and this was considered statistically significant (both p=0.023). Conclusion. There was no statistically significant difference in the VEP parameters of the individuals with the ABO blood groups hence same VEP normal values can be used for ABO blood groups.

Comparison of surgical effect in active and inactive Dysthyroid Optic Neuropathy after Endoscopic Transnasal Medial Orbital Decompression.

To evaluate and compare the changes in orbital soft tissue volume and visual function after endoscopic transnasal medial orbital decompression in patients with active and inactive dysthyroid optic neuropathy (DON). This prospective, cohort study recruited 112 patients (112 eyes) with DON who were divided into an active and inactive DON group (56 eyes each) by clinical activity scores. All patients underwent endoscopic transnasal medial orbital decompression. The pre- and post-operative orbital soft tissue volumes were measured with high-resolution computed tomography (CT) using Mimics software. Visual function, including best-corrected visual acuity (BCVA), visual field (VF), and visual evoked potential (VEP), was recorded before and after surgery. Preoperatively, compared with the inactive DON group, the active DON group had greater extraocular muscle volume (EMV) and EMV/orbital volume (OV) ratio, but worse BCVA, VF, and exophthalmos. Postoperatively, although the EMV slightly increased, with the enlarged medial rectus muscle contributing dramatically, the EMV/OV ratio decreased in patients with DON. Besides, visual function including BCVA, VF, VEP and exophthalmos was also improved in both groups after surgery. There were no significant differences in postoperative OV; EMV; EMV/OV ratio; and the BCVA, VF, and VEP parameters between both groups (all P > 0.05). Patients with DON who did not respond well to steroids, regardless of disease activity, may benefit from orbital decompression via the decrease in the proportion of EMV in OV, especially patients with active DON, who showed more improved visual function than patients with inactive DON.

Efficacy of ozone therapy on visual evoked potentials in diabetic patients

BackgroundThe involvement of the central nervous system is a frequent yet underestimated complication of diabetes mellitus. Visual evoked potentials (VEP) are a simple, sensitive, and noninvasive method for detecting early alterations in central optic pathways. The objective of this paralleled randomized controlled trial was to evaluate the impact of ozone therapy on visual pathways in diabetic patients.MethodsSixty patients with type 2 diabetes visiting clinics of Baqiyatallah university in Tehran (Iran) hospital were randomly assigned to two experimental groups: Group 1 (N = 30) undergoing a cycle of 20 sessions of systemic oxygen-ozone therapy in addition to standard therapy for metabolic control; Group 2 (N = 30)—serving as control—receiving only standard therapy against diabetes. The primary study endpoints were two VEP parameters; P100 wave latency and P100 amplitude at 3 months. Moreover, HbA1c levels were measured before the start of treatment and three months later as secondary study endpoint.ResultsAll 60 patients completed the clinical trial. P100 latency significantly reduced at 3 months since baseline. No correlation was found between repeated measures of P100 wave latency and HbA1c (Pearson’s r = 0.169, p = 0.291). There was no significant difference between baseline values and repeated measures of P100 wave amplitude over time in either group. No adverse effects were recorded.ConclusionsOzone therapy improved the conduction of impulses in optic pathways of diabetic patients. The improved glycemic control following ozone therpay may not fully explain the reduction of P100 wave latency though; other mechanistic effects of ozone may be involved.

Retinal sensitivity and gaze fixation evaluated by microperimetry in subjects with type 2 diabetes: two independent parameters that explore different neuronal circuits

Background and aimsRetinal sensitivity (RS) and gaze fixation (GF) assessed by retinal microperimetry are useful and complementary tools for identifying mild cognitive impairment (MCI) in patients with type 2 diabetes (T2D). The hypothesis is that RS and GF examine different neural circuits: RS depends only on the visual pathway while GF reflects white matter complex connectivity networks. The aim of the study is to shed light to this issue by examining the relationship of these two parameters with visual evoked potentials (VEP), the current gold standard to examine the visual pathway.Materials and methodsConsecutive T2D patients > 65 years were recruited from the outpatient clinic. Retinal microperimetry (MAIA 3rd generation) and visual evoked potentials (VEP) (Nicolet Viking ED). RS (dB), GF (BCEA63%, BCEA95%) (MAIA) and VEP (Latency P100ms, Amplitude75–100 uV) were analyzed.ResultsThirty three patients (45% women, 72.1 ± 4.6 years) were included. VEP parameters significantly correlated with RS but not with GF.ConclusionsThese results confirm that RS but not GF depends on the visual pathway, reinforcing the concept that they are complementary diagnostic tools. Used together can further increase the value of microperimetry as screening test for identifying T2D population with cognitive impairment.

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.

Visual Evoked Potential After Levodopa in Amblyopic Eyes

Purpose to study the clinical and electrophysiological changes after Levodopa in amblyopic eyes. Methods: Fifty patients with amblyopia (20 hypermetropic anisometropia and 20 myopic anisometropic amblyopia,10 astigmatic amblyopic) were included in this study, Levodopa was administered daily for 6 weeks associated with occlusion therapy and visual training. The drug was stopped and patients continued on occlusion therapy associated with visual training for another 6 weeks. Then gradual reduction of occlusion time and visual training was performed for another 6 weeks, and finally all treatments were stopped for 6 weeks. Visual acuity and visual evoked potentials (VEP), including both multifocal VEP (MFVEP) and Pattern VEP (PVEP) were recorded before the treatment, at 1,6,12,18,24weeks after beginning of treatment. Results: Significant improvement of visual acuity (mean 0.50), with stabilization at the end of the 6th week associated with improved PVEP and MFVEP parameters was reported. Stabilization of the visual improvement after stoppage the treatment without any deterioration of vision or VEP parameters. Conclusion: Improved visual acuity with stabilization can be achieved with combined Levodopa, occlusion and visual training therapy confirmed with VEP improvement.

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 & 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.

An optimized procedure to record visual evoked potential in mice

Visual evoked potential (VEP) is commonly used to evaluate visual acuity in both clinical and basic studies. Subdermal needle electrodes or skull pre-implanted screw electrodes are usually used to record VEP in rodents. However, the VEP amplitudes recorded by the former are small while the latter may damage the brain. In this study, we established a new invasive procedure for VEP recording, and made a series of comparisons of VEP parameters recorded from different electrode locations, different times of day (day and night) and bilateral eyes, to evaluate the influence of these factors on VEP in mice. Our data reveal that our invasive method is reliable and can record VEP with good waveforms and large amplitudes. The comparison data show that VEP is greatly influenced by active electrode locations and difference between day and night. In C57 or CD1 ONC (optic nerve crush) models and Brn3bAP/AP mice, which are featured by loss of retinal ganglion cells (RGCs), amplitudes of VEP N1 and P1 waves are drastically reduced. The newly established VEP procedure is very reliable and stable, and is particularly useful for detecting losses of RGC quantities, functions or connections to the brain. Our analyses of various recording conditions also provide useful references for future studies.

OC19: Visual evoked potentials monitoring during neurosurgical operations: optimizing the protocol

Visual evoked potentials (VEPs) are used for intraoperative neurophysiological monitoring (IONM) during surgeries involving visual system. But unlike other IONM modalities, no standards have been yet developed for the intreoperative VEPs monitoring. Here we consider VEPs registration parameters contributing to their successful and useful monitoring. Methods. 144 consecutive surgeries (288 eyes) performed using VEPs monitoring were analyzed retrospectively. Stimulation: flash intensity 25000 lx, duration 10 ms, frequency ∼1 Hz, 20–100 responses averaged. 7 electrodes placed, three pairs chosen. Bandpass filtering: [10-20] – [200-400] Hz (chosen individually). Alarm: standard 10–50% criteria. Anesthesia: propofol – 110 surgeries, sevoflurane – 14, combined – 20. In 27 surgeries, propofol-to-sevoflurane transition performed after dura closure. Results. Chosen electrode pairs: Oz-A1&Oz-A2 in 45% of surgeries, O1/O2/Oz-CPz in 25%, O1/O2/Oz-Fz in 24%. Chosen frequency filters: 100–400 Hz (200 Hz in 67%) low-pass, 5–20 Hz (10 Hz in 59%) high-pass. Anesthesia effects: 5,9% unresponsive non-blind eyes for propofol and 18,5% for sevoflurane anesthesia. After propofol-to-sevoflurane transition VEPs disappeared in 22% of cases. Alarm criteria had been reached for 73 eyes. Full recovery observed later in 62%, partial in 23%, no recovery in 15% of cases. Postoperative visual impairments among eyes with: successful VEPs monitoring without alarms – 3%, full recovery after alarms – 7%, incomplete or no recovery – 23%, unobtainable VEPs – 14%. Conclusions. Optimal parameters of VEPs recording for IONM should be selected individually and differs from the standards for clinical diagnostics. VEPs recording under (low-to-moderate-dose) sevoflurane is often possible, but the propofol anesthesia is preferable.

Visual Evoked Potentials as Potential Biomarkers of Visual Function in Patients with Primary Sjögren’s Syndrome

Visual evoked potentials (VEP) are changes in potentials that arise in the central nervous system. In the interpretation of the VEP test results, it is assumed that the elongation of the latency time is caused by the demyelination of the nerve fibers, and the axon damage is responsible for the decrease in the amplitude. The observed VEP deviations are not specific for specific diseases, but indicate disturbances in visual conductivity. VEP may play a diagnostic role in the early detection of visual involvement. The aim of the study was the functioning of visual pathway assessment on the basis of visual evoked potentials (VEP) examination, in patients with primary Sjögren’s Syndrome (pSS), without focal symptoms of central nervous system disorder. The effect of disease activity, as assessed by clinical parameters and antibody levels (anti-Ro52, SSA, and SSB), on the central nervous system was also evaluated. Thirty-two consecutive patient with pSS (31 females, 1 male) were included in the study. VEP was performed at baseline, and after 6 (T6) years. Their results were compared longitudinally between the baseline and T6, depending on the duration of the disease and treatment. The immunological activity of pSS was also analyzed. The group of patients showed a significant prolongation of the P100 implicit time (105.5 ± 5.1 vs. 100.6 ± 3.9; p = 0.000) and a significant higher the P100-N145 amplitude (12.3 ± 4.1 vs. 9.4 ± 3.0; p = 0.000). Abnormalities in electrophysiological parameters of VEP at baseline correlated with presentation of anti-Ro52 antibodies and aching joints. At baseline, the P100 implicit time was shorter for the patients with pSS than for those at T6 (105.50 ± 5.1 vs. 109.37 ± 5.67; p = 0.002). pSS patients without CNS involvement presented with dysfunction of visual pathway, as revealed by VEP abnormalities. Relationships were found between VEP parameters and with present of anti-Ro52 antibodies and aching joints. VEP may be a useful method for assessment and monitoring of subclinical visual deficit in the course of pSS.

Comparison of Visual Evoked Potentials in Patients Affected by Optic Neuritis From Multiple Sclerosis or Neuromyelitis Optica Spectrum Disorder.

To compare the visual evoked potentials (VEPs) of optic neuritis (ON) patients with multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and controls. To evaluate correlations between VEP and optical coherence tomography (OCT), contrast sensitivity (CS), and automated perimetry. Fifty-five eyes with ON from 29 patients (MS = 14 and NMOSD = 15) and 57 eyes from 29 controls were evaluated using VEP, automated perimetry, CS, and optical coherence tomography. Three groups were analyzed: 1) MS eyes with history of ON (ON-MS), 2) NMOSD eyes with ON (ON-NMOSD), and 3) healthy controls. Groups were compared and associations between the parameters were tested. Compared to controls, ON-MS eyes showed significantly delayed N75 and P100 latencies when using a medium-sized stimulus (30'), and delayed P100 latency when using a large stimulus (1.5°), but similar amplitudes. Compared to controls, ON-NMOSD eyes showed significantly lower N75/P100 amplitudes (both stimulus sizes) and P100/N135 amplitudes (with the 30' stimulus), but latencies did not differ, except for a delayed P100 latency with the 30' stimulus. When comparing the 2 ON groups using the 1.5° stimulus, there was significant delay in P100 latency in ON-MS eyes and a reduction in N75/P100 amplitude in ON-NMOSD eyes. Peripapillary retinal nerve fiber layer, macular inner retinal layers, and CS measurements were significantly smaller in ON patients than in controls. A strong correlation was found between VEP parameters and inner retinal layer thickness in ON-NMOSD eyes. ON-MS eyes had normal amplitude and delayed VEP latency, whereas ON-NMOSD eyes displayed reduced amplitude and preserved latency when elicited by checkerboard stimulus with large 1.5° checks. Under such conditions, VEP may help distinguish resolved MS-related ON from resolved NMOSD-related ON.

The retinal vasculature pathophysiological changes in vision recovery after treatment for indirect traumatic optic neuropathy patients

PurposeTo evaluate the retinal vasculature pathophysiological changes of indirect traumatic optic neuropathy (ITON) patients after effective surgery.MethodsMonocular ITON patients who underwent endoscopic trans-ethmosphenoid optic canal decompression (ETOCD) or conservative treatments in Zhongshan Ophthalmic Center from January 2017 to June 2020 were recruited. Visual acuity (VA), visual evoked potential (VEP), oxygen saturation of retinal blood vessels (SO2), and optical coherence tomography angiography (OCT-A) were measured. All patients were followed up at least 3 months after treatments.ResultsA total of 95 ITON patients were recruited, including 77 patients who underwent ETOCD and 18 patients who underwent conservative treatments. After treatments, more patients received ETOCD (59/77 = 76.6%) presented with improved VA compared with the patients with conservative treatments (6/18 = 33.3%). Compared with the pre-therapeutic measurements, VEP were significantly improved after surgery in ETOCD-treated patients (P < 0.05). Latent periods of P1 and N2, as well as amplitude of P2 of VEP parameters, showed more sensitive to vision recovery (P < 0.05). Retinal artery SO2 and the differences between arteries and veins were improved in ETOCD-treated patients (P < 0.05). Meanwhile, with OCT-A examination, the retinal thickness and retinal vessel density were notably better in ETOCD-treated patients after surgery than that in patients received conservative treatments (P < 0.05).ConclusionsVision recovery after effective treatment of ITON patients was associated with the increased oxygen saturation of retinal vessels, better availability of oxygen in the retina, greater vessel density, and thicker retinas, which might further underlie the vasculature mechanism of vision recovery in ITON patients.

Does levetiracetam use affect visual evoked potentials in the treatment of childhood epilepsy?

Side effects of antiepileptic drugs vary depending on the drug itself, drug dose and duration of use. One of these side effects is related to vision. Patients who had been ordered visual evoked potential (VEP) measurements for various reasons between October 1st, 2017 and October 1st, 2019 at a pediatric neurology outpatient clinic and who were on levetiracetam monotherapy for at least six months for the treatment of focal/generalized epilepsy were included in the study and their files were scanned retrospectively (study group: SG). Patient files were evaluated for age, gender, dose and duration of levetiracetam use, presence of a family history of epilepsy, EEG result, cranial magnetic resonance imaging and VEP test results and the parameters were recorded. Twenty-four patients of similar age range without epilepsy were included in the study as the control group (CG). Eighteen patients 8 boys (44.4%), 10 girls (55.6%) and 24 healthy controls 9 boys (37.5%), 15 girls (62.5%) were included in the study and control groups, respectively. No statistically significant difference was found when the mean VEP latencies were compared between the patient and control groups for the right (P=0.451) and left (P=0.323) eyes. There was a statistically significant difference between the groups, respectively, when VEP amplitudes of the right and left eyes of the SG and CG were compared (P=0.001; P=0.001). There is no correlation between levetiracetam dose and duration of treatment and VEP parameters. The data obtained in this study showed that levetiracetam use affected VEP amplitude outcome but did not affect VEP latency outcome in pediatric patients.

Visual Evoked Potential Responses after Photostress in Migraine Patients and Their Correlations with Clinical Features.

In the past few years, researchers have detected subtle macular vision abnormalities using different psychophysical experimental tasks in patients with migraine. Recording of visual evoked potential (VEP) after photostress (PS) represents an objective way to verify the integrity of the dynamic properties of macular performance after exposure to intense light. VEPs were recorded before and after PS in 51 patients with migraine (19 with aura (MA) and 22 without aura (MO) between attacks, and 10 recorded during an attack (MI)) and 14 healthy volunteers. All study participants were exposed to 30 s of PS through the use of a 200-watt bulb lamp. The P100 implicit time and N75-P100 amplitude of the baseline VEP were compared with those collected every 20 s up to 200 s after PS. VEP parameters recorded at baseline did not differ between groups. In all groups, the VEP recordings exhibited a significant increase in implicit times and a reduction in amplitude at 20 s after the PS. In migraine, the percentage decrease in amplitudes observed at 20 s after photostress was significantly lower than in healthy volunteers, in both MO and MA patients, but not in MI patients. When data for MO and MA patients were combined, the percentage of amplitude change at 20 s was negatively correlated with the number of days that had elapsed since the last migraine attack, and positive correlated with attack frequency. We showed dynamic changes of recovery of VEP after PS depending on the migraine cycle. This finding, in conjunction with those previously attained with other neuromodulatory interventions using VEPs, leads us to argue that migraine-disease-related dysrhythmic thalamocortical activity precludes amplitude suppression by PS.

Visual evoked potentials changes with surgery in primary congenital glaucoma: a pilot study.

To report the flash visual evoked potential (VEP) findings in children with primary congenital glaucoma (PCG) before and after successful surgical control of the intraocular pressure (IOP). The study enrolled children presenting with PCG to the Ophthalmology Department of Alexandria Main University Hospital in the period between June and December 2019. All study participants were subjected to a standard protocol of examination, to confirm the diagnosis of PCG. The child was then referred for flash VEP testing. Peaks were designated as negative and positive waves in a numerical sequence (N1, P1, N2, P2, N3 and P3). The child was then scheduled for surgery within 1week of presentation. Postoperative VEP testing was scheduled as soon as feasible and was conducted in the same way as the preoperative VEP testing. The study was conducted on 11 (four right) eyes of eight (five males) children. The mean ± standard deviation of the age of the study children at presentation and at postoperative VEP testing was 3.5 ± 1.6 and 5.1 ± 3.0months, respectively. The study eyes mean ± standard deviation IOP at presentation and at postoperative VEP testing was 23.0 ± 6.7 and 8.3 ± 2.4mmHg, respectively (p < 0.0001). There were a statistically insignificant reduction in P2 implicit time (p = 0.235) and a statistically insignificant increase in each of N1-P1 (p = 0.15) and N2-P2 (p = 0.67) amplitudes postoperatively than preoperatively. IOP elevation in PCG adversely affects the optic nerve function, but, at least in the short term, has no permanent detrimental effect on the optic nerve function as evidenced by the improvement in the VEP parameters.

Early disability in ambulatory patients with multiple sclerosis: optical coherence tomography versus visual evoked potentials, a comparative study

BackgroundMultiple sclerosis (MS) is a common cause of neurological disabilities in adults and commonly affects the visual pathway. The objective of this study is to assess and compare the sensitivity of visual evoked potentials (VEP) and optical coherence tomography (OCT) as measures of early disability in ambulatory patients with MS.MethodsForty-four patients with MS with Expanded Disability Status Scale (EDSS) of ≤ 4.5 (ambulatory patients) and 14 healthy controls participated in this study. Patients were classified into 3 groups according to EDSS. Patients with EDSS of 0–1.5 formed the “No disability,” patients with EDSS of 2–3 formed the “Minimal to mild disability,” and finally patients with EDSS of 3.5–4.5 formed the “Moderate to significant disability” groups. N75/P100 amplitude, P100 latency, retinal nerve fiber layer (RNFL) thickness, and ganglion cell layer complex (GCLC) thickness were measured.ResultsPatients showed significantly lower N75/P100 amplitude, higher P100 latency, lower RNFL, and GCLC thicknesses compared to controls. However, there were non-significant changes in P100 latency, N75/P100 amplitude, and GCLC thickness among the 3 groups for both patients with and without history of optic neuritis (ON). On contrary, RNFL thickness was significantly different between the three groups for both patients with and without history of ON. Factorial ANOVA revealed non-significant disability × History of ON interaction.ConclusionCompared to VEP parameters, RNFL thickness was a sensitive correlate with the various degrees of early disability in fully ambulatory patients with MS whatever the history of ON.

Retinal ganglion cell complex and visual evoked potentials in levetiracetam treatment

Purpose To examine central macular, RNFL (retinal nerve fibre layer), GCC (ganglion cell complex) thicknesses; and VEPs (visual evoked potential) in epileptic patients using levetiracetam for at least one year. Materials and Methods Sixteen focal epileptic patients receiving levetiracetam monotherapy and 16 healthy subjects were included in the study. Central macular, RNFL and GCC thicknesses according to spectral domain OCT (optical coherence tomography); and VEPs parameters were compared between patients and healthy subjects. Results The mean age of patient and control groups were 40 ± 16 and 38 ± 12 years respectively (p > 0.05). The patient group was on levetiracetam therapy for 64 ± 45 (12–168) months. Central macular thickness was thinner in the patient group (p = 0.008). There was no difference among groups regarding RNFL thicknesses. GCC thicknesses in all quadrants were similar among groups, except the superior quadrant; which was thinner in the patient group (p = 0.03). P100 amplitude in 30 min pattern was lower in the patient group (p = 0.04). N135 latency in 15 min (p = 0.03) and 7 min patterns (p = 0.01) was longer in the patient group. Conclusion Central macular and GCC thicknesses; and VEP parameters in patients receiving levetiracetam treatment may differ from healthy subjects.

The Effect of Maintenance Treatment with Twice-Daily or Prolonged Once-Daily Tacrolimus Formulation on Visual Evoked Potentials in Stable Kidney Transplant Recipients.

In kidney transplant recipients (KTRs), uraemia-induced central nervous system damage partly subsides, while the long-lasting exposure to tacrolimus may cause pathologic visual evoked potentials (VEP) findings, which have not been investigated yet. Thus, the aim of the present study was to assess the effect of tacrolimus maintenance treatment on bioelectrical function of optic nerves in stable KTRs. Sixty-five stable KTRs were enrolled, including 30 patients treated with twice-daily (Prograf) and 35 patients treated with prolonged once-daily (Advagraf) tacrolimus formulation. In all patients, pattern and flash VEP measurements were performed. Tacrolimus dosing and exposure were also analyzed. Overall, 129 eyes were analyzed. In pattern VEP, both (1°) and (15′) latencies of P100 waves were significantly longer, whereas (1°) and (15′) amplitudes were lower in the Advagraf group as compared with the Prograf group. Multivariate regression analyses revealed that the use of Advagraf (vs. Prograf) was independently associated with longer (1°) and (15′) P100 latencies and lower corresponding amplitudes, whereas log tacrolimus daily dose was only related to amplitudes in a whole study group. In flash VEP, log tacrolimus trough level was associated with negative changes in P2 wave amplitude irrespective of tacrolimus formulation, whereas its association with P2 latency was observed only in the Prograf group. Both the type of tacrolimus formulation and drug exposure influenced the VEP parameters in stable KTRs.

Vision training with VEP biofeedback in amblyopia after the critical period.

The purpose of this study was to investigate the benefits of vision training with visual evoked potentials (VEP) biofeedback in amblyopia after the critical period in 8 to 17-year (11.5 ± 3.1) old children. Ten participants with monocular amblyopia after the critical period underwent a 10-week, 20-session vision training program with the Retimax Vision Trainer device. During each session, the participants were instructed to be as focused as possible onto the fixation point in the middle of the screen. The size of the fixation point and the pitch of the background sound were changing according to VEP parameters and thus provided the participants real-time feedback of their visual performance. The mean BCVA improvement across our group was 0.12 LogMAR (p < 0.01). There was also a significant increase in contrast sensitivity to the FACT chart across all spatial frequencies (all p < 0.05). Electrophysiologic data revealed higher steady-state visual evoked potentials (SS-VEP) amplitudes and correspondingly lower fixation point values in the last 2weeks of training compared to the first 2weeks (both p < 0.01). Due to unexplainably low VEP amplitude levels in later trainings compared to those in the beginning in two participants, we have not found a significant correlation between the increase in BCVA and the increase in SS-VEP amplitude (p = 0.88). At the follow-up at 2 and 12months following the end of training, both BCVA and contrast sensitivity remained within the levels achieved at the end of training. In some participants, however, no improvement of BCVA was observed. The tested vision training approach demonstrates modest but stable improvement of psychophysical parameters as well as objective characteristics in amblyopia after the critical period. Real-time SS-VEP can be used as an objective parameter to monitor participants' attention during vision training stimulation.