Visual Evoked Potentials Research Articles

Prolonged Visual Evoked Potential Latencies in Dogs Naturally Infected with Canine Distemper Virus

Canine distemper (CD) is a deadly, multi-system infection caused by a Morbillivirus. The canine distemper virus (CDV) frequently affects the nervous system with demyelinating leukoencephalitis, the most common neurological lesion. The disease has been linked to multiple sclerosis (MS) in humans due to similar clinical presentation and pathophysiological mechanisms. In MS, visual evoked potentials (VEPs) have been identified as a reliable marker for disease progression, enabling the early detection of clinically suspected lesions. The aim of this study was to determine if there are any abnormalities in VEP responses in dogs with neurological CD. Visual evoked potentials and electroretinogram (ERG) were recorded at both the cranial and spinal levels in dogs naturally infected with CDV and in healthy dogs. The results in the CDV-infected group revealed a bilateral increase in the latency of N1, P1, N2, P2, and N3 waves of the VEPs, without any alterations in their amplitudes. No significant differences were observed in the ERG between the groups. These results suggest that altered VEP responses could serve as an early diagnostic indicator of neurological damage caused by distemper. Therefore, conducting these studies could potentially aid in the detection of central nervous conduction disorders during the subclinical phases of the disease.

Leber’s idiopathic stellate neuroretinitis - A clinical case

Neuroretinitis is a type of optic neuropathy characterized by an acute unilateral visual loss with optic disc swelling and macular star. A 26-year-old male presented with sudden blurring of vision in the right eye for 15 days. There were no other constitutional symptoms. On examination, visual acuity and color vision were impaired in the right eye. Visual-evoked potential showed a lower amplitude with increased latency on the right side. Perimetry showed centrocaecal scotoma. The right eye fundus showed a distinct neuroretinitis pattern Despite extensive investigation, no specific cause was identified, hence diagnosed as Leber’s idiopathic stellate neuroretinitis. The patient was started on oral prednisolone. Follow-up showed significant improvement.

Monitoring of visual-evoked potentials during fat packing in endoscopic resection of a giant pituitary adenoma

Background: Endoscopic transsphenoidal surgery has become a mainstay surgical approach for sellar pathologies and can effectively decompress mass effects on the optic nerves. Visual-evoked potentials (VEPs) have been utilized as an intraoperative adjunct during endoscopic transsphenoidal surgery to monitor the integrity of the optic pathways, but the data surrounding its reliability and efficacy remain heterogeneous. Case Description: An 80-year-old male underwent endoscopic transsphenoidal resection of a pituitary macroadenoma with preoperative visual deficits related to optic nerve compression. During fat packing of the resection cavity, a decrease in VEPs was noted, which seemingly improved after partial fat removal, although with paradoxically reduced VEP latencies. Despite this, the patient developed a visual field deficit postoperatively, requiring re-operation for further removal of the fat packing. Conclusion: This was a case of initially poorly formed VEPs that deteriorated and apparently improved following surgical intervention. The finding of shortened latencies of the VEPs was likely from noise contamination, creating the illusion of improved signal amplitudes. We recommend careful assessment of VEP data for baseline reproducibility, particularly in patients with pre-existing visual field deficits. Appropriate anesthetic selection is also important to reduce noise interference from the electroencephalogram.

Posterior short ciliary arteries ischemia following embolization of anterior ethmoid artery to treat dural arteriovenous fistulas: a case report

BackgroundThe Onyx™ Liquid Embolic System is a non-adhesive liquid embolic agent, which has been proved by the US FDA for embolization of lesions in the peripheral and neurovasculature since 2005. We reported a case of ischemic optic neuropathy after using Onyx-18 to embolize the anterior ethmoid arteries that feeding dural arteriovenous fistulas (DAVF).Case presentationA 57-year-old Asian male presented with anterior cranial fossa DAVF underwent embolotherapy by delivering Onyx-18 through a microcatheter into the anterior ethmoid arteries under angiography guidance. The interventional procedure was successful and no clear evidence was found pointing to untargeted occlusive embolus. But after the surgery the patient experienced delayed painless vision loss in the right eye (RE). The fundoscopy showed unilateral papilledema with pale optic disc in RE, accompanied by significant edema and thickening in the retinal nerve fiber layer (RNFL) of macula. The fundus fluorescence angiography showed that most of the optic disc in RE had postponed or absent fluorescence filling. Visual evoked potential (VEP) confirmed that the amplitude of the P100 component was decreased in RE without significant prolongation of the latency. The patient was diagnosed with anterior ischemic optic neuropathy, but immediate pulse steroid therapy failed to rescue his vision.ConclusionPreoperative evaluation of the patient’s hemodynamic status and fundus examination are essential for assessing the risk of ischemic ocular complications, and the non-adhesive liquid embolic agent Onyx-18 should be used cautiously during endovascular embolization of intracranial artery.

Layer-specific dynamics of local field potentials in monkey V1 during electrical stimulation.

The mammalian neocortex, organized into six cellular layers or laminae, forms a cortical network within layers. Layer specific computations are crucial for sensory processing of visual stimuli within primary visual cortex. Laminar recordings of local field potentials (LFPs) are a powerful tool to study neural activity within cortical layers. Electric brain stimulation is widely used in basic neuroscience and in a large range of clinical applications. However, the layer-specific effects of electric stimulation on LFPs remain unclear. To address this gap, we conducted laminar LFP recordings of the primary visual cortex in monkeys while presenting a flash visual stimulus. Simultaneously, we applied a low frequency sinusoidal current to the occipital lobe with offset frequency to the flash stimulus repetition rate. We analyzed the modulation of visual-evoked potentials with respect to the applied phase of the electric stimulation. Our results reveal that only the deeper layers, but not the superficial layers, show phase-dependent changes in LFP components with respect to the applied current. Employing a cortical column model, we demonstrate that these in vivo observations can be explained by phase-dependent changes in the driving force within neurons of deeper layers. Our findings offer crucial insight into the selective modulation of cortical layers through electric stimulation, thus advancing approaches for more targeted neuromodulation.

Role of Visual Evoked Potential and Ocular Trauma Score as Predictors of Visual Recovery in Eye Globe Injuries.

Evaluate visual evoked potential (VEP) and ocular trauma score (OTS) efficacy in predicting visual potential in globe trauma without optic nerve involvement. A retrospective cohort study analyzed clinical data from eye globe injury cases undergoing flash VEP between January 2000 and May 2021. Inclusion criteria: flash VEP completion within 48 hours, pre-surgical intervention. Exclusions: head trauma, optic nerve injuries. Abnormal VEP: <7 µV amplitudes, >120ms latencies. The OTS was computed, and penetrating injuries were categorized. Of 85 eyes meeting the criteria (mean age: 31.9±20.6 years, 82.4% male), the median follow-up was 22 months. OTS directly correlated with the amount of Early Treatment Diabetic Retinopathy Study letters gained at follow-up and was inversely correlated with ocular penetration extent, and VEP signal amplitude. VEP amplitude is inversely correlated with maintaining/improving visual acuity. Positive predictive value for normal VEP predicting maintained/improved visual acuity: 75.6%, negative predictive value: 21.3%. In blunt trauma, baseline VEP amplitude had superior predictive value compared to penetrating injury. This study highlights a correlation between VEP signal amplitude and OTS with visual outcomes in traumatic eye injuries without optic nerve involvement. OTS emerges as a reliable VEP substitute, particularly in blunt trauma cases, where baseline VEP amplitude predicts visual recovery more accurately than penetrating injuries.

A Case of Compressive Optic Neuropathy Caused by Orbital Emphysema

Purpose: We report a patient with compressive optic neuropathy (CON) in whom visual acuity (VA) was restored after removing conjunctival emphysema through the conjunctiva.Case summary: A 55-year-old man was transferred to emergency department complaining of decreased VA in the right eye after trauma to the right temporal side of the head. The best-corrected visual acuity (BCVA) was 0.6 in the right eye. We confirmed a relative afferent pupillary defect and limited eye movement inferiorly in the right eye. The patient had blown his nose several times while being transferred to the hospital. On silt-lamp examination, there was conjunctival emphysema of the right eye. Orbital computed tomography showed a medial wall fracture of the right orbit and orbital emphysema above the optic canal. The P100 wave was delayed in the visual evoked potential (VEP) exam, and there was a decreased peripheral visual field on the Humphrey visual field test. Based on these findings, we diagnosed CON and treated him accordingly. To decompress the intra-orbital area, we injected mannitol intravenously, applied intraocular pressure-lowering and antibiotic eye drops in the right eye, and removed part of the conjunctival emphysema through the conjunctiva. At the 3-week follow-up, the BCVA had improved to 1.0 in the right eye with a normalized P100 wave on the VEP exam.Conclusions: In a case of CON caused by orbital emphysema after trauma, it is important to decrease the intra-orbital pressure as soon as possible to enable a good prognosis for the VA.

Demyelination and neurodegeneration early in experimental autoimmune encephalomyelitis contribute to functional deficits in the anterior visual pathway

Impaired visual function is a prevalent feature of optic neuritis (ON) in multiple sclerosis (MS). Abnormal visual evoked potential (VEP) findings of increased latencies, reduced amplitudes and abnormal waveforms as well as decreased retinal nerve fiber layer (RNFL) assessed by optical coherence tomography (OCT) are hallmarks of ON-induced visual dysfunction. Here we utilized the experimental autoimmune encephalomyelitis (EAE) mouse model of MS to investigate the functional and pathological progression during early (before any clinical symptoms), peak (initial maximal clinical symptoms), and late (chronic disease for > 3 weeks) disease stages. Demyelination and initial stages of axon damage were observed in early EAE. Significant demyelination, inflammation, increased axon damage and impaired P1/N2 amplitudes and latencies by VEP were seen in middle and late EAE groups. A decrease in RNFL thickness by OCT was observed only during late EAE. NanoString analysis of optic nerves from late EAE indicated elevated inflammation-related genes, reduced myelin-related genes, and changes in axon degeneration-related genes. Early inflammatory demyelination and functional deficits of the visual pathway, if untreated, may lead to severe irrecoverable axon damage in EAE. These studies potentially help explain the progression of visual dysfunction during MS.

Decoding Visual Responses: Insights into Chronic Migraine and Medication Overuse Headache with Electrophysiological Analysis.

Background/Objectives: Habituation and sensitization are opposite phenomena that play a role in the pathophysiology of episodic migraine and its progression to chronic migraine (CM). There have been just a few studies that have investigated these phenomena in patients with medication overuse headache (MOH) in comparison to those with chronic migraine (CM) and healthy controls (HCs), and the findings have been inconsistent. Methods: We measured and examined visual evoked potentials (VEPs) in 81 patients with MOH and 24 patients with CM, as well as 24 HCs. The VEPs were used to assess sensitization by analysing the amplitude of the first block (100 sweeps) and to evaluate habituation by measuring the amplitude response decrement after six blocks. We further examined patients diagnosed with MOH based on their acute medication type and after a 3-week acute medication withdrawal program. Results: There were no significant differences between groups in terms of the first N1-P1 VEP amplitude block and its habituation. It was found that patients with MOH had a greater drop in the amplitude of the VEP P1-N2 complex after repeated stimulation than patients with CM or HC. The VEP parameters showed no significant differences based on the specific overused drug and after a 3-week acute medication withdrawal. Conclusions: We propose that the results obtained in patients with MOH indicate an abnormal activation of inhibitory circuits in the parieto-occipital region in response to repeated modulatory stimuli.

Use of Electrophysiology in the Diagnosis of Optic Nerve Disorders

Visual electrodiagnostic tests are non invasive, easily applicable that enable objective evaluation of the functions of the visual pathways. The most preferred among these test are; electroretinography (ERG), pattern electroretinography (PERG), electrooculography (EOG) and visual evoked potential (VEP). ERG is used to evaluate retinal functions especially rod and cone responses. PERG is used to evaluate functions of macular and retinal ganglion cells. EOG is used to evaluate retinal pigment epithelium functions. VEP is preferred method for evaluating the visual pathways up to the optic nerve and occipital cortex as a whole. Photopic negative response (PhNR) is originates from the electrical activity of amacrine and glial cells and also mostly retinal ganglion cells. In this study, VEP, PERG and PhNR tests which are the most preferred in the diagnosis of optic nerve disorders, will be mainly mentioned.

Investigating causal effects of pupil size on visual discrimination and visually evoked potentials in an optotype discrimination task.

Pupil size primarily changes to regulate the amount of light entering the retina, optimizing the balance between visual acuity and sensitivity for effective visual processing. However, research directly examining the relationship between pupil size and visual processing has been limited. While a few studies have recorded pupil size and EEG signals to investigate the role of pupil size in visual processing, these studies have predominantly focused on the domain of visual sensitivity. Causal effects of pupil size on visual acuity, therefore, remain poorly understood. By manipulating peripheral background luminance levels and target stimulus contrast while simultaneously recording pupillometry and EEG signals, we examined how absolute pupil size affects visual discrimination and visually evoked potentials (VEP) in a task using optotype mimicking the Snellen eye chart, the most common assessment of visual acuity. Our findings indicate that both higher background luminance levels and higher target contrast were associated with improved target discrimination and faster correct reaction times. Moreover, while higher contrast visual stimuli evoked larger VEPs, the effects of pupil size on VEPs were not significant. Additionally, we did not observe inter-individual correlations between absolute pupil size and discrimination performance or VEP amplitude. Together, our results demonstrate that absolute pupil size, regulated by global luminance level, played a functional role in enhancing visual discrimination performance in an optotype discrimination task. The differential VEP effects of pupil size compared to those of stimulus contrast further suggested distinct neural mechanisms involved in facilitating visual acuity under small pupils.

Clinically-probed mechanisms of action in Fragile-X Syndrome fail to normalize translational EEG phenotypes in Fmr1 knockout mice

Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by Fragile X Messenger Ribonucleoprotein (FMRP) deficiency. Electroencephalogram (EEG) changes in FXS include alterations of oscillatory activity and responses to sensory stimuli, some of which have been back-translated into rodent models by knocking-out the Fragile X messenger ribonucleoprotein 1 gene (Fmr1-KO). However, the validity of these EEG phenotypes as objective biomarkers requires further investigation.Potential pharmacotherapies such as mGluR5 inhibitors (e.g. CTEP; 2-chloro-4-((2,5-dimethyl-1-(4-(trifluoromethoxy)phenyl)-1H-imidazol-4-yl)ethynyl)pyridine), GABABR agonists (e.g. arbaclofen) and δ-containing GABAAR agonists (e.g. gaboxadol) have not translated into clinical success despite rescuing many phenotypes in the Fmr1-KO model. Yet none of these treatments have been assessed on EEG phenotypes in the Fmr1-KO model. Therefore, we set out to discover new EEG phenotypes in Fmr1-KO mice, using “task-free” and auditory-evoked (AEPs) and visually-evoked potential (VEP) paradigms, and probe their modulation by CTEP, arbaclofen and gaboxadol, using within-subjects designs.First, we report Fmr1-KO-associated EEG abnormalities that closely resemble those observed in FXS, including elevated gamma-band power, reduced alpha/beta-band coherence, increased AEPs and delayed VEPs. Secondly, we found that pharmacological treatment, at best, only partially normalized EEG phenotypes. CTEP restored alpha/beta-band coherence and AEP amplitudes but failed to normalize gamma power and VEP latencies. Conversely, arbaclofen reduced gamma power but did not restore coherence or AEP amplitudes and further delayed VEPs. Gaboxadol did not normalize any EEG phenotypes.We conclude that these compounds have limited ability to normalize these EEG phenotypes.

NEUROCOGNITIVE EVALUATION OF PATIENTS WITH DIGEORGE SYNDROME

BackgroundDiGeorge syndrome (DGS), the most common microdeletion syndrome, affects multiple organs, including the heart, the nervous system, and the immune system. In this study, we aimed to evaluate the clinical, laboratory, brain MRI, and neurocognitive findings of our patients with DGS. MethodsClinical and laboratory data of fifty-two patients with DGS between June 2000- March 2022 were evaluated retrospectively. Brain MRI and neuropsychological tests were performed to assess the neurocognitive status of the patients. ResultsFifty-two patients (28 males and 24 females) were included in our study. Fifteen of them died during the follow-up. All 37 patients who are alive had partial DGS. The median age of patients was ten years and seven months, and the median age at diagnosis was five years and four months. Bilateral conduction deceleration in the anterior visual pathways in 6 (20%) of 30 patients was determined by the VEP (Visual Evoked Potentials). The auditory brainstem evoked potential test (BAEP) showed sensorineural hearing loss in 11 out of 30 (36.6%) patients. Brain MRI disclosed brain parenchymal abnormalities in 18 out of 25 (72%) patients. Impairments in executive functions, expressive language, and verbal memory were noted in 18 patients who were neuropsychologically assessed. ConclusionIt is important to keep in mind that patients with DiGeorge syndrome may be accompanied by neurocognitive findings. Awareness of the potential for underlying psychiatric and neurodevelopment disorders is key to anticipatory guidance, optimization of therapies, and maximizing life quality.

Anti-seizure effects of norepinephrine-induced free fatty acid release.

The brain's ability to rapidly transition between sleep, quiet wakefulness, and states of high vigilance is remarkable. Cerebral norepinephrine (NE) plays a key role in promoting wakefulness, but how does the brain avoid neuronal hyperexcitability upon arousal? Here, we show that NE exposure results in the generation of free fatty acids (FFAs) within the plasma membrane from both astrocytes and neurons. In turn, FFAs dampen excitability by differentially modulating the activity of astrocytic and neuronal Na+, K+, ATPase. Direct application of FFA to the occipital cortex in awake, behaving mice dampened visual-evoked potential (VEP). Conversely, blocking FFA production via local application of a lipase inhibitor heightened VEP and triggered seizure-like activity. These results suggest that FFA release is a crucial step in NE signaling that safeguards against hyperexcitability. Targeting lipid-signaling pathways may offer a novel therapeutic approach for seizure prevention.

Unlocking Early Detection and Intervention Potential: Analyzing Visual Evoked Potentials (VEPs) in Adolescents/Teenagers with Narcotics Abuse Tendencies from the TelUnisba Neuropsychology EEG Dataset (TUNDA)

Narcotics abuse has extensive negative impacts on individuals, families, and society, including physical harm to organs and mental health disorders. Addressing teenage narcotics problems requires collaborative efforts involving educational institutions, families, and psychologists. Currently, narcotics has increasingly targeted teenagers, becoming a serious issue that demands special attention in prevention and treatment. Handling narcotic problems at the adolescent level necessitates close collaboration among educational institutions, families, and the community, including psychologists. Emphasizing the importance of early detection and prevention, this study proposes a method to detect the possibility of narcotic abuse in adolescents using the Go/No-Go Association Task (GNAT) test designed by psychologists. The study introduced the TelUnisba Neuropsychology EEG Dataset (TUNDA), an open EEG dataset with data on the emotional and habitual aspects of drug abuse in Indonesia, classified into "normal" and "risk" by psychologists. The processed EEG signal is the visual evoked potential (VEP) within 1000 milliseconds following the visual stimulus onset. The data is classified as “slow” and “fast” based on respondent's responses using MobileNetV2 architecture. Results showed MobileNetV2 achieved the highest accuracy for both normal and risk categories, with accuracies of 0.86 and 0.85 respectively. This study obtained ethical clearance and received funding support from Telkom University and Universitas Islam Bandung, with technical assistance from the Smart Data Sensing Laboratory. The authors declare no conflicts of interest related to this study.

Intraoperative monitoring of visual evoked potentials: experience of 240 operations

Background. Intraoperative monitoring (IOM) of visual evoked potentials (VEPs) is used to inform surgeons about impacts on the visual system in order to prevent iatrogenic visual impairment. The VEP monitoring use become widespread only in the last decade; nowadays, there is no generally accepted methodology for its implementation, and the effectiveness of VEP monitoring and the factors determining it have not been sufficiently studied.Aim. The aim of the study was to investigate the factors influencing the VEP monitoring feasibility and effectiveness.Materials and methods. Data from 240 consecutive neurosurgical operations performed using VEP monitoring were retrospectively reviewed. IOM data (registration parameters, presence and type of VEP changes), patient characteristics (gender and age, tumor type and location, presence of preoperative visual dysfunctions), anesthesia parameters and postoperative changes in vision were studied. Statistical analysis was performed using χ2 and Mann–Whitney tests.Results. VEPs were obtained in 91.3 % of eyes with completely or partially preserved vision. The main factors reducing the chances to record VEPs successfully are preoperative visual disorders and the use of inhalation anesthesia. A personalized approach to the selection of reference electrodes and frequency filtering parameters makes it possible to reduce the number of averagings required for VEP recording and accelerate informing surgeons. With successful monitoring 59.1 % of eyes had no noticeable VEP changes; 5.8 % of eyes had signs of intraoperative improvement; 35.1 % had signs of deterioration. Among the last category, 60.7 % of eyes had full VEPs recovery afterwards. After surgery, new visual disorders were detected in 2.6 % of eyes without signs of intraoperative deterioration, in 6.7 % – with temporary deterioration, and in 19.3 % – with signs of deterioration persisted until IOM is finished. Assessing the sensitivity and specificity of VEP monitoring is hampered by the possibility of complications in the early postoperative period and IOM influence on the course and results of the operation. The proportion of total resections was maximal when VEP monitoring was successful. In the subgroup without preoperative visual impairments, the alarms during monitoring were associated with decrease in proportion of total resections proportion due to increase in proportion of subtotal resections.Conclusion. VEP monitoring with a personalized approach allows effective monitoring of visual functions preservation during neurosurgical operations.

Longitudinal effects of prenatal alcohol exposure on visual neurodevelopment over infancy.

Prenatal alcohol exposure (PAE) affects neurodevelopment in over 59 million individuals globally. Prior studies using dichotomous categorization of alcohol use and comorbid substance exposures provide limited knowledge of how prenatal alcohol specifically impacts early human neurodevelopment. In this longitudinal cohort study from Cape Town, South Africa, PAE is measured continuously-characterizing timing, dose, and drinking patterns (i.e., binge drinking). High-density electroencephalography (EEG) during a visual-evoked potential (VEP) task was collected from infants aged 8 to 52 weeks with prenatal exposure exclusively to alcohol and matched on sociodemographic factors to infants with no substance exposure in utero. First trimester alcohol exposure related to altered timing of the P1 VEP component over the first 6 months postnatally, and first trimester binge drinking exposure altered timing of the P1 VEP components such that increased exposure was associated with longer VEP latencies while increasing age was related to shorter VEP latencies (n = 108). These results suggest alcohol exposure in the first trimester may alter visual neurodevelopmental timing in early infancy. Exploratory individual-difference analysis across infants with and without PAE tested the relation between VEP latencies and myelination for a subsample of infants with usable magnetic resonance imaging (MRI) T1w and T2w scans collected at the same time point as EEG (n = 47). Decreased MRI T1w/T2w ratios (an indicator of myelin) in the primary visual cortex (n = 47) were linked to longer P1 VEP latencies. Results from these two sets of analyses suggest that prenatal alcohol and postnatal myelination may both separately impact VEP latency over infancy. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Skin Carotenoids Are Related to Cognitive Abilities among Toddlers

BackgroundCarotenoids are antioxidant pigments that deposit in human tissues (e.g., skin, macula, and brain) upon dietary consumption. The health implications of skin carotenoids, which reflect overall dietary carotenoid consumption, have not been adequately studied in younger populations. ObjectivesThis work aimed to examine links between skin carotenoids and cognitive, language, and motor skills among toddlers. A secondary aim explored relationships between skin carotenoids and neurophysiologic outcomes of sensory memory [i.e., mismatch negativity (MMN)] and the functional integrity of the visual pathway [i.e., visual evoked potentials (VEPs)]. MethodsToddlers aged 12–18 mo (n = 45) were included in a cross-sectional study. Skin carotenoids were measured with reflection spectroscopy via the Veggie Meter®. Cognitive, language, and motor skills were measured using the Bayley Scale of Infant and Toddler Development IV Screening Test (BSID-IV). MMN and VEPs were collected with an auditory oddball task and a pattern reversal task, respectively, using electroencephalography. Analyses adjusted for age, household income, highest level of parental education, and total carotenoid intake (mg/1000 kcal). ResultsRegression modeling revealed that skin carotenoids significantly related to cognition (β = 0.24; P = 0.04) and not to any other BSID-IV subsets. Neither MMN nor VEP outcomes significantly related to skin carotenoids. ConclusionsGreater skin carotenoids were selectively related to cognition, indicating that carotenoids may play a role in cognition in toddlers. Additional research is needed to understand links between skin carotenoids and specific domains of cognitive function and brain health in early life.

Fluoxetine as a possible treatment for adult amblyopia: results of a double-blind, randomized, placebo-controlled trial

PurposeTo evaluate the effects of oral fluoxetine on visual acuity and visual-evoked potential (VEP) parameters in adults with amblyopia. MethodsIn this randomized clinical trial, adults (>18 years of age) with anisometropic or strabismic amblyopia were assigned randomly to a treatment (fluoxetine) group or a placebo group. Standard treatments for amblyopia (glasses prescription and patching) were prescribed for 4 months for all patients. The first group received fluoxetine (20 mg per day) and the second group received a placebo for 3 months. Visual acuity evaluation and VEP were performed before and after treatment. ResultsA total of 55 participants were included: 29 in the fluoxetine group and 26 in the placebo group. Mean age was 27.2 ± 8.6 years (18-54). The mean logMAR visual acuity of the amblyopic eye improved by 0.20 ± 0.24 (0-0.8) in the fluoxetine group (P < 0.001) and by 0.08 ± 0.15 (0-0.7) in the placebo group (P = 0.01); mean logMAR improvement was significantly higher in the fluoxetine group than in the placebo group (P = 0.04). At the end of the study, mean visual acuity of the fluoxetine group (0.36 ± 0.21 log MAR) was better than the placebo group (0.43 ± 0.35 log MAR). Among the VEP parameters, N75 amplitude did not change significantly in either group relative to baseline, but the changes were statistically significantly different between the two groups (P = 0.05); N135 latency improved from baseline in the fluoxetine group (P = 0.03). ConclusionsIn our study cohort, fluoxetine treatment for adult amblyopia resulted in greater improvement in visual acuity than placebo.

Study of Visual Evoked Potentials in Schoolchildren: A Promising Aid to Pediatric Ophthalmology.

Background Visual evoked potential (VEP) is a noninvasive investigation conducted to identify abnormalities in the visual system. It is especially suitable for young children who are unable to express visual symptoms or participate in conventional vision tests. This study was undertaken to examine the VEP among schoolchildren to assess the functionality of their optic pathway. Methodology This short-term observational study was performed in the Clinical Neurophysiology Unit of the Physiology Department of a rural medical college. The study population consisted of 60 schoolchildren aged 7-12. Both eyes were examined for transient pattern reversal VEP recordingsusing a Recorders & Medicare Systems Electromyography-Evoked Potential recorder (RMS EMG-EP MARK-II Pvt. Ltd., Chandigarh, India). Results VEPs were analyzed for latency and amplitude of the main components, namely P100, N70, and N155. The results showedmarkedly extended P100 latency in33.33%, i.e., eight outof 24 eyes of standard (std.) III children. Similar latency prolongation was obtained in 36.36% (eight out of 22)eyes of std. IV, 30% (six of 20 eyes) of std. V, 13.63% (three of 22 eyes) of std. VI, and 50% (eight of 16 eyes) in std. VII and VIIIchildren. A markedly reduced P100 amplitude was observedin two of 20 eyes (10%) of std. V, two of 16 eyes (12.5%) in std. VII and VIIIchildren, amounting to a P100amplitude abnormality in5%eyesin toto. The interocular differences in all VEP parameters amongthe subjects were statistically insignificant. Conclusion In schoolchildren in whom normal latencies and amplitudes were obtained, the presence of reproducible VEPs indicated the normal functionalstatus of their visual pathway. On the other hand,in those children where alteredVEP findings were found, it hinted towardcomplementary informationthat they may have underlying ocular disordersthat were yet to be diagnosed. Hence, this study provides insight into the assessment of visual system function, which is primarily difficult in young children.