Visual Evoked Potentials Research Articles

How should visual function monitoring be performed and interpreted in surgery for suprasellar tumors?

Preservation of visual function is important in surgery for suprasellar tumors. Visual evoked potentials (VEPs) are expected to play an important role in monitoring visual function during surgery. Given the lack of information in this field, the authors aimed to investigate the effects of optic nerve compression caused by suprasellar tumors to understand the possible usefulness of VEP monitoring using off-response (OFR) VEP. Eleven healthy volunteers who underwent surgery for standard record confirmation and 32 patients with optic chiasm lesions who underwent surgery were examined. Preoperative, postoperative, and intraoperative VEPs were recorded. Propofol anesthesia was administered during intraoperative VEP monitoring. Patients who underwent surgery were monitored using the same stimulation method during surgery. Light stimulation was given from a luminant pad on the eyelids, and low-intensity stimulation with continuous 500-msec emission and 500 msec off was performed. The luminescence intensity of the stimulation was at a maximum of 8000 lx with three attenuation steps, each of which was recorded repeatedly. The OFR potentials and delay latencies decreased as stimulus intensity decreased. In the patient with temporal hemianopia, monocular stimulation produced the highest OFR in the contralateral occipital lobe of the stimulated eye. The authors recorded preoperative, intraoperative, and postoperative VEP in 32 patients and observed intraoperative changes in 23 patients. In the cases where VEP declined during intraoperative recording, it recovered when surgery was discontinued. Furthermore, 3 patients eventually achieved a higher VEP than that achieved at the beginning of the surgery, and rapid recovery was confirmed with visual field examination immediately after surgery. Of the 5 patients in whom VEP did not recover during surgery, 3 showed decreased visual field and acuity after surgery. In 15 cases, potential dropped temporarily but returned to the original potential, and their visual field recovered after surgery. OFR has a diagnostic element in the visual field, in which the maximal potential was recorded on the opposite side of the stimulus with monocular stimulation. Unambiguous determination required stimulation of different intensities in both eyes or 1 eye and multiple recording electrodes placed in the occiput. Monitoring the OFR provides real-time alerts, making it a valuable tool for visual function evaluation in suprasellar surgery.

Visual evoked potential in generalized joint hypermobility: A case-control study.

Generalized joint hypermobility (GJH) can be the result of several hereditary connective tissue disorders, especially Ehlers-Danlos syndrome. Cerebrovascular manifestations are among the most common complications in this disorder, and understanding their extent can help better diagnosis and prevention of hazardous events. We investigated visual evoked potential (VEP) changes in patients with GJH and compared them with healthy individuals. Our case-control study included 90 patients who fulfilled the Beighton score (B score) for joint hypermobility and other 90 healthy participants. All of them went under VEP study, and the amplitude and latency of the evoked potential (P100) were compared to each other. The Case group had significantly higher B score (7.18±0.967 vs. 1.18±0.712), P100 latency (110.23±6.64ms vs. 100.18±4.273ms), and amplitude (6.54±1.26mv vs. 6.50±1.29mv) compared with the Control group, but the difference was only significant regarding B score, and P100 latency (p-value <.0001). Moreover, both latency and amplitude of P100 had significantly positive correlations with the B score in the Case group (p-value <.0001), but such correlations were not found in the Control group (p-value=.059). Our study could reveal VEP changes, especially significant P100 latency in GJH patients without previous neurologic or musculoskeletal disorders. Whether these changes are due to GJH itself or are predictive of inevitable neurologic disease or visual pathway involvement, particularly Multiple Sclerosis needs further investigation with longer follow-up periods.

Psychophysical, electrofunctional, and morphological evaluation in naïve neovascular AMD patients treated with intravitreal anti-VEGF.

The aim of this study was to investigate the retinal morpho-functional characteristics of patients with neovascular wet age-related macular degeneration (nAMD) treated with intravitreal injection (IV) of aflibercept (AFL). The study was conducted on 35 patients previously diagnosed with type 1 nAMD who received a fixed-dosing regimen of aflibercept injections over 12 months. The goal was to assess trends in visual abilities over time by measuring visual acuity (VA), contrast sensitivity (CS), visual evoked potentials (VEPs), and spectral domain-optical coherence tomography (SD-OCT). The same psychophysical, electro-functional, and morphological tests administered at baseline (T0) were repeated 4 to 8 weeks after the last aflibercept injection (Tn), resulting in a total of six examinations. At Tn, all subjects exhibited improved VA for both far and near distances compared to values detected at T0. Similarly, VEP amplitude and latency values at Tn showed a greater P100 improvement than those observed at T0. Additionally, the CS examination at Tn demonstrated improvement, particularly at high spatial stimulation frequencies. The Tn SD-OCT results highlighted a reduction in macular thickness compared to T0 values. This exploratory research indicates that intravitreal injections of AFL, following a fixed-dosing regimen, represent a valuable therapeutic approach for enhancing visual performance. This conclusion is supported by comprehensive statistical analysis of psychophysical, electro-functional, and morphological examinations within the same group of patients with nAMD, as demonstrated for the first time.

The Assessment of Vision in Children with Severe Learning Difficulties: A Systematic Review

The Assessment of Vision in Children with Severe Learning Difficulties: A Systematic Review

Connectome spectrum electromagnetic tomography: A method to reconstruct electrical brain source networks at high-spatial resolution.

Connectome spectrum electromagnetic tomography (CSET) combines diffusion MRI-derived structural connectivity data with well-established graph signal processing tools to solve the M/EEG inverse problem. Using simulated EEG signals from fMRI responses, and two EEG datasets on visual-evoked potentials, we provide evidence supporting that (i) CSET captures realistic neurophysiological patterns with better accuracy than state-of-the-art methods, (ii) CSET can reconstruct brain responses more accurately and with more robustness to intrinsic noise in the EEG signal. These results demonstrate that CSET offers high spatio-temporal accuracy, enabling neuroscientists to extend their research beyond the current limitations of low sampling frequency in functional MRI and the poor spatial resolution of M/EEG.

Balancing the Senses: Electrophysiological Responses Reveal the Interplay between Somatosensory and Visual Processing During Body-Related Multisensory Conflict.

In the study of bodily awareness, the predictive coding theory has revealed that our brain continuously modulates sensory experiences to integrate them into a unitary body representation. Indeed, during multisensory illusions (e.g., the rubber hand illusion, RHI), the synchronous stroking of the participant's concealed hand and a fake visible one creates a visuotactile conflict, generating a prediction error. Within the predictive coding framework, through sensory processing modulation, prediction errors are solved, inducing participants to feel as if touches originated from the fake hand, thus ascribing the fake hand to their own body. Here, we aimed to address sensory processing modulation under multisensory conflict, by disentangling somatosensory and visual stimuli processing that are intrinsically associated during the illusion induction. To this aim, we designed two EEG experiments, in which somatosensory- (SEPs; Experiment 1; N = 18; F = 10) and visual-evoked potentials (VEPs; Experiment 2; N = 18; F = 9) were recorded in human males and females following the RHI. Our results show that, in both experiments, ERP amplitude is significantly modulated in the illusion as compared with both control and baseline conditions, with a modality-dependent diametrical pattern showing decreased SEP amplitude and increased VEP amplitude. Importantly, both somatosensory and visual modulations occur in long-latency time windows previously associated with tactile and visual awareness, thus explaining the illusion of perceiving touch at the sight location. In conclusion, we describe a diametrical modulation of somatosensory and visual processing as the neural mechanism that allows maintaining a stable body representation, by restoring visuotactile congruency under the occurrence of multisensory conflicts.

Bone Marrow-derived Mesenchymal Stem Cell Therapy in Retinitis Pigmentosa.

To determine the effectiveness of bone marrow-derived mesenchymal stem cell therapy on visual acuity and visual field in patients with retinitis pigmentosa. Stem cell treatment in retinitis pigmentosa provides improvement in visual acuity and visual field. Forty-seven eyes of 27 patients diagnosed with retinitis pigmentosa were included in our study. Allogeneic bone marrow-derived mesenchymal stem cells were administered by deep subtenon injection. Complete routine ophthalmological examinations, optical coherence tomography (Zeiss, Cirrus HD-OCT) measurements, and visual field (Humphrey perimetry, 30-2) tests were performed on all patients before the treatment and on the 1st, 3rd, and 6th month after treatment. The best corrected visual acuities of the patients were determined by the Snellen chart and converted to logMAR. Visual evoked potential (VEP) and electroretinogram (ERG) examinations of the patients before the treatment and on the 6th month after the treatment were performed (Metrovision) data were compared. Visual acuities were 0.74 ± 0.49 logMAR before treatment and 0.61 ± 0.46 logMAR after treatment. Visual acuity had a statistically significant increase (p < 0.001). The visual field deviation was found to be -27.16 ± 5.77 dB before treatment and -26.59 ± 5.96 dB after treatment (p = 0.005). The ganglion cell layer was 46.26 ± 12.87 μm before treatment and 52.47 ± 12.26 μm after treatment (p = 0.003). There was a significant improvement in Pattern VEP 120º P100 amplitude compared to that before the treatment (4.43 ± 2.42 μV) and that after the treatment (5.09 ± 2.86 μV) (p = 0.013). ERG latency measurements were 18.33 ± 15.39 μV before treatment and 20.87 ± 18.64 μV after treatment for scotopic 0.01 (p = 0.02). ERG latency measurements for scotopic 3.0 were 20.75 ± 26.31 μV before treatment and 23.10 ± 28.60 μV after treatment (p = 0.014). Retinitis pigmentosa is a progressive, inherited disease that can result in severe vision loss. In retinitis pigmentosa, the application of bone marrow-derived mesenchymal stem cells by deep subtenon injection has positive effects on visual function. No systemic or ophthalmic side effects were detected in the patients during the 6-month follow-up period.

Cortical dynamics in visual areas induced by the first use of multifocal contact lenses in presbyopes

A common non-spectacle strategy to correct presbyopia is to provide simultaneous images with multifocal optical designs. Understanding the neuroadaptation mechanisms behind multifocal devices usage would have important clinical implications, such as predicting whether patients will be able to tolerate multifocal optics. The aim of this study was to evaluate the brain correlates during the initial wear of multifocal contact lenses (CLs) using high-density visual evoked potential (VEP) measures. Fifteen presbyopes (mean age 51.8 ± 2.6 years) who had previously not used multifocal CLs were enrolled. VEP measures were achieved while participants looked at arrays of 0.5 logMAR Sloan letters in three different optical conditions arranged with CLs: monofocal condition with the optical power appropriate for the distance viewing; multifocal correction with medium addition; and multifocal correction with low addition. An ANOVA for repeated measures showed that the amplitude of the C1 and N1 components significantly dropped with both multifocal low and medium addition CL conditions compared to monofocal CLs. The P1 and P2 components showed opposite behavior with an increase in amplitudes for multifocal compared to monofocal conditions. VEP data indicated that multifocal presbyopia corrections produce a loss of feedforward activity in the primary visual cortex that is compensated by extra feedback activity in extrastriate areas only, in both early and late visual processing.

Comparative analysis of VEP signals discrimination methods based on time-frequency transformation and CNN-2D

The Visual Evoked Potential (VEP) examination is used to analyze the appropriate functioning of the optical pathways from the retina to the visual cortex. In hospitals, the diagnosis made by physicians is based mainly on reading the temporal trace and identifying the latency P100. However, after a considerable research effort, it has been confirmed that this method is subjective and relatively less reliable. In our work, we report different approaches to resolve the inadequacy of traditional classification, by studying the efficiency of VEP signal classification in a comparative approach using 3 models: Model A: STFT-CNN, Model B: CWT-CNN, and Model C: Wigner-Ville-CNN, therefore we evaluate in the same context the effectiveness of using a pre-trained 2D CNN structure. The time-frequency transformation allows us to generate two-dimensional data from one-dimensional signals to bring out the integrated features that are not valued in the temporal plot, and then exploit them for good discrimination between the two classes, in order to be able to use a CNN-2D classification architecture, taking into consideration the advantages offered by this architecture in terms of the involvement of the attribute extraction phase and its efficiency in classifying 2D data. The results provided by the different scenarios proved that the Wigner-Ville transformation combined with a pre-trained CNN architecture can be considered a good method in terms of different performance metrics, which demonstrates that it is a successful candidate for providing significant assistance to physicians in their analysis of VEP signals.

The clinical efficacy of preoperative flash visual evoked potential (VEP) for mature cataracts without a response to pattern VEP.

This study aims to assess the effectiveness of the preoperative flash visual evoked potential (VEP) test in predicting postoperative visual acuity for monocular mature cataract cases when compared to the contralateral normal eye. The study included 60 patients, each with a monocular mature cataract diagnosis, who underwent preoperative flash VEP testing showing no pattern VEP response. Subsequently, phacoemulsification was performed. The relationship between the flash VEP test latency values (P1, N2, P2) and amplitude value (N2-P2), and the degree of visual acuity recovery 3 months post-cataract surgery, was evaluated using the LogMAR scale. Furthermore, a linear regression analysis was conducted to explore the connection between preoperative flash VEP components and postoperative visual acuity. The average age of the patients was 65.4 ± 13.6 years, with a range of 43 to 87 years. The study included 36 males and 24 females. A significant disparity in visual acuity was observed between the preoperative and 3-month postoperative stages (p < 0.001). The preoperative flash VEP test for mature cataracts revealed significant delays in P1, N2, and P2 latency, as well as a reduction in N2-P2 amplitude potential when compared to the contralateral normal eye (p < 0.001). Notably, delayed P2 latency and reduced N2-P2 amplitude potential were particularly indicative of poor visual acuity prognosis after cataract surgery in the multiple regression analysis (p < 0.05). The N2-P2 amplitude potential was the important value that exhibited statistically significant results, with an area under the curve (AUC) of 80% sensitivity and 88% specificity, using a cutoff value of 6.07 μV. In cases of monocular mature cataract, a reduction in N2-P2 amplitude potential compared to the contralateral normal eye emerged as the most reliable predictor of postoperative visual prognosis following cataract surgery.

Neurophysiological Alterations of the Visual Pathway in Posterior Cortical Atrophy: Systematic Review and a Case Series.

The clinical features of posterior cortical atrophy (PCA), a rare condition often caused by Alzheimer's disease, have been recently defined, while little is known about its neurophysiological correlates. To describe neurophysiological alterations of the visual pathway as assessed using visual field test (VF), visual evoked potentials (VEP), and electroretinogram (ERG) in PCA patients. Studies reporting VF, VEPs, and ERG in PCA patients were selected according PRISMA method. Of the 323 articles that emerged from the literature, 17 included the outcomes of interest. To these data, we added those derived from a patient cohort enrolled at our clinic. The literature review included 140 patients, half of them (50%) presented with homonymous hemianopia or quadrantanopia. VEPs were available in 4 patients (2 normal findings, 1 decreased amplitude, and 1 increased latency) and ERG in 3 patients (substantially normal findings). Our case series included 6 patients, presenting with homonymous lateral hemianopia in 50% and contralateral cortical atrophy. VEPs showed normal amplitude in 66-83% according to the stimulation check, and increased latency in 67% in absence of myelin damage on MRI. Latency was increased in both eyes in 50% and only on one side in the other 50%. Such alterations were observed in patients with more severe and symmetric atrophy. ERG showed normal findings. Neurophysiological investigations of the visual pathway in PCA are almost absent in literature. Alterations involve both amplitude and latency and can be also monocular. A multiple-point involvement of the optical pathway can be hypothesized.

From periphery to center, untold story of pure neuritic leprosy: an electrophysiological study.

Pure neuritic leprosy (PNL) is uncommon form of leprosy involving peripheral nerves. Some isolated case reports have shown imaging changes in the central nervous system (CNS) and also impairment in visual evoked potential (VEP), somatosensory evoked potential (SSEP) and brain stem auditory-evoked potentials (BAEPs) parameters in PNL, but there is lack of large study. This prospective observational study evaluates impairment in these central conduction studies among PNL patients. We screened patients with leprosy presenting with features of neuropathy and/or thickened nerves. Patients with bacilli-positive nerve biopsies were included in the study and subjected to routine tests along with nerve conduction study (NCS), VEP, tibial SSEP and BAEPs. Parameters of these studies were analyzed based on data from previous studies. Of 76 patients screened for PNL 49 had positive findings in biopsy. Most of patients were male and mean age group was 46.35 ± 15.35years. Mononeuritis multiplex was most common NCS pattern in 46.93% (23/49) patients. We found abnormal VEP in 13 out of 35 patients (37.14%). Similarly abnormal SSEP and BAEPs among 42.85% and 40% patients respectively. This study shows that in PNL significant number of patients have subclinical CNS involvement. Exact pathophysiology of CNS involvement is not known till now but study of VEP, SSEP and BAEPs parameter may help in early diagnosis of PNL.

Bexarotene leads to durable improvements in visual evoked potential latency: A follow-up study of the Cambridge Centre for Myelin Repair One trial

The Cambridge Centre for Myelin Repair One (CCMR-One) trial showed that 6 months of bexarotene reduces visual evoked potential (VEP) latency in people with relapsing-remitting multiple sclerosis (MS). In a single-centre follow-up study of these participants, we re-examined full-field VEP and clinical assessments. Twenty participants (12 bexarotene and 8 placebo) were seen on average 27 months after their trial involvement. In an analysis of all eyes with recordable signal (24 bexarotene and 14 placebo), the adjusted bexarotene-placebo treatment difference in P100 latency was −7.79 (95% confidence interval (CI) = −14.76, −0.82) ms, p = 0.044. We conclude that there were durable improvements in VEP latency, suggesting long-term benefits from exposure to a remyelinating drug.

Knocking out the LRRK2 gene increases sensitivity to wavelength information in rats

Leucine-rich repeat kinase 2 (LRRK2) is a gene related to familial Parkinson’s disease (PD). It has been associated with nonmotor symptoms such as disturbances in the visual system affecting colour discrimination and contrast sensitivity. This study examined how deficiency of LRRK2 impacts visual processing in adult rats. Additionally, we investigated whether these changes can be modelled in wild-type rats by administering the LRRK2 inhibitor PFE360. Visual evoked potentials (VEPs) and steady-state visual evoked potentials (SSVEPs) were recorded in the visual cortex and superior colliculus of female LRRK2-knockout and wild-type rats to study how the innate absence of LRRK2 changes visual processing. Exposing the animals to stimulation at five different wavelengths revealed an interaction between genotype and the response to stimulation at different wavelengths. Differences in VEP amplitudes and latencies were robust and barely impacted by the presence of the LRRK2 inhibitor PFE360, suggesting a developmental effect. Taken together, these results indicate that alterations in visual processing were related to developmental deficiency of LRRK2 and not acute deficiency of LRRK2, indicating a role of LRRK2 in the functional development of the visual system and synaptic transmission.

Simulating the Effects of Partial Neural Conduction Delays in the Visual Evoked Potential.

The purpose of this study was to understand the double peaks or broadening of P100 observed in some cases of optic neuritis by inducing conduction delays in healthy eyes through stimulus luminance manipulation in analogy to the perceptual Pulfrich effect. Checkerboard pattern reversal visual evoked potentials (VEPs) with check sizes of 0.8degrees, 0.4degrees, and 0.2degrees were recorded in healthy participants using two experiment variants. Variant (1) involved binocular stimulation with inter-ocular luminance difference achieved by a 1.8 neutral density (ND) filter, along with monocular control conditions. Variant (2) included monocular stimulation with hemifields having a luminance difference (half of monitor with ND filter), along with single-hemifield control conditions. In both variants, VEP curves under mixed stimulation were compared to synthesized VEPs computed from offline summation of curves from the relevant control conditions, followed by assessing P100 characteristics. Despite considerable variability between participants, the binocular variant demonstrated marked differences between VEPs from mixed recordings and synthesized curves, whereas in the hemifield variant, agreement was strong. The anticipated double peak or broadened deflection pattern was observed to varying extents in participants, often contingent on check size, with nominal peak time frequently failing to indicate partial conduction delays. The present findings corroborate the hypothesis that nominal peak time does not always reflect conduction delays if only a subset of fiber bundles is affected. Peak shape might provide additional diagnostic evidence of a partial conduction delay. Enhancing the understanding of VEP waveform changes associated with partial conduction delays could offer diagnostic insights for optic neuritis.

Visual evoked potentials in multiple sclerosis: P100 latency and visual pathway damage including the lateral geniculate nucleus

ObjectiveTo explore associations of the main component (P100) of visual evoked potentials (VEP) to pre- and postchiasmatic damage in multiple sclerosis (MS). Methods31 patients (median EDSS: 2.5), 13 with previous optic neuritis (ON), and 31 healthy controls had VEP, optical coherence tomography and magnetic resonance imaging. We tested associations of P100-latency to the peripapillary retinal nerve fiber layer (pRNFL), ganglion cell/inner plexiform layers (GCIPL), lateral geniculate nucleus volume (LGN), white matter lesions of the optic radiations (OR-WML), fractional anisotropy of non-lesional optic radiations (NAOR-FA), and to the mean thickness of primary visual cortex (V1). Effect sizes are given as marginal R2 (mR2). ResultsP100-latency, pRNFL, GCIPL and LGN in patients differed from controls. Within patients, P100-latency was significantly associated with GCIPL (mR2 = 0.26), and less strongly with OR-WML (mR2 = 0.17), NAOR-FA (mR2 = 0.13) and pRNFL (mR2 = 0.08). In multivariate analysis, GCIPL and NAOR-FA remained significantly associated with P100-latency (mR2 = 0.41). In ON-patients, P100-latency was significantly associated with LGN volume (mR2 = −0.56). ConclusionsP100-latency is affected by anterior and posterior visual pathway damage. In ON-patients, damage at the synapse-level (LGN) may additionally contribute to latency delay. SignificanceOur findings corroborate post-chiasmatic contributions to the VEP-signal, which may relate to distinct pathophysiological mechanisms in MS.

Brain mechanism of acupuncture for children with anisometropic amblyopia: a resting functional magnetic resonance imaging study based on voxel-mirrored homotopic connectivity.

To explore the brain mechanism of acupuncture for children with anisometropic amblyopia using the voxel-mirror homotopic connectivity (VMHC) analysis method of resting functional magnetic resonance imaging (rs-fMRI) technology based on clinical effectiveness. Eighty children with anisometropic monocular amblyopia were randomly divided into two groups: control (40 cases, 1 case of shedding) and acupuncture (40 cases, 1 case of shedding) groups. The control group was treated with glasses, red flash, grating, and visual stimulations, with each procedure conducted for 5min per time. Based on routine treatment, the acupuncture group underwent acupuncture of "regulating qi and unblocking meridians to bright eyes", Jingming (BL1), Cuanzhu (BL2), Guangming (GB37), Fengchi (GB20) acupoints were taken on both sides, with the needle kept for 30min each time. Both groups were treated once every other day, three times per week, for a total of 4wk. After the treatment, the overall curative effect of the two groups and the latency and amplitude changes of P100 wave of pattern visual-evoked potential were counted. At the same time, nine children with left eye amblyopia were randomly selected from the two groups and were scanned with rs-fMRI before and after treatment. The differences in the brain regions between the two groups were compared and analyzed with VMHC. Chi-square test showed a notable difference in the total efficiency rate between the acupuncture (94.87%) and control groups (79.49%). Regarding the P100 wave latency and amplitude, the acupuncture group had significantly shorter latency and higher amplitude of P100 wave than the control group. Moreover, the VMHC values of the bilateral temporal lobe, superior temporal gyrus, and middle temporal gyrus were notably increased in the acupuncture group after treatment. Acupuncture combined with conventional treatment can significantly improve the corrected visual acuity and optic nerve conduction in children with anisometropic amblyopia. Compared with the conventional treatment, the regulation of acupuncture on the functional activities of the relevant brain areas in the anterior cerebellum may be an effective acupuncture mechanism for anisometropic amblyopia.

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

Abstract&#x0D; Introduction &amp; 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.&#x0D; 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.&#x0D; 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.&#x0D; 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.

Neuromyelitis Optica with Negative AQP-4 Antibody

Abstract&#x0D; Introduction : Neuromyelitis Optica (NMO) or neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the central nervous system that causes demyelination of the optic nerve and spinal cord. Approximately 75% of cases have antibodies against aquaporin 4 (AQP-4 Antibody).&#x0D; Case Illustration : A 42 years old male presented with progressing blurred vision in his right eye for 3 weeks. He described there was a black spot in his central vision which gradually enlarged to his peripheral vision, headache for 4 months, and transient tingling sensation and weakness on the left arm for 1 week. Positive RAPD in the right eye and signs of optic neuritis on funduscopy in Opthalmology examination. Campimetry examination revealed generalized depression in the right eye. The visual evoked potential (VEP) was consistent with right optic nerve demyelination. Spine MRI showed extensive transverse myelitis lesions &gt;3 spinal cord hyperintensity on the level of C2-C6. However, the serum AQP-4 antibody was negative. The patient was treated with corticosteroid, and neuroprotector and was also being treated alongside the neurology department.&#x0D; Discussion : NMO is a rare autoimmune disease. NMO is characterized by segmented demyelination and inflammation of the spinal cord and the optic nerves which gives many ocular signs and symptoms like optic neuritis. A negative test result does not rule out the diagnosis of NMO. Brain and spine MRI plays an important role in diagnosing NMO. Treatment of NMO consists of corticosteroid and plasmapheresis or intravenous immunoglobulin.&#x0D; Conclusion : This case describes a diagnosis of NMO with a Negative AQP-4 antibody.

Swollen Disc in Children : Diagnostic Approach

Swollen disc is a clinical sign of eye disease, neurological or systemic. It happened because of the increase in intracranial. Some of the conditions that cause swollen disc are optic neuritis, optic neuropathy, retinal vein occlusion, papilloedema, or pseudo-disc swelling (e.g drusen). In children, the incidence of swollen discs differs from that in adults. Diagnosis can be made using OCT (Optical Coherence Tomography), ocular ultrasound, VEP (Visual Evoked Potential) and MRI (Magnetic Resonance Imaging) of the orbit and head