P300 Wave Research Articles

A comparative study of visual evoked potential parameters in type 2 diabetes mellitus patients with increasing duration

Background: Type 2 diabetes mellitus (T2DM) is endocrine disorder showing increasing prevalence worldwide. Chronic hyperglycemia of diabetes affects various organs of our body and causes dysfunction and failure of them. Diabetic retinopathy is a grave complication of diabetes mellitus. Diabetes causes neurodegeneration in retina well before the frank retinopathy. Early detection of these changes by visual evoked potentials (VEPs) may prevent the development of this complication in future, so it can be used as a screening test. Aims and Objectives: The study aimed to compare the VEP changes with the duration of T2DM. Materials and Methods: An analytical case–control study was done after obtaining Ethical Committee permission. VEPs were recorded with RMS EMG EP MK II machine. The duration of the diabetes was used to divide patients into two groups: Group I - 30 patients with disease duration <15 years; and Group II - 30 patients with T2DM with disease duration >15 years. Analysis and processing of the data was done by using statistical software SPSS23.0 using t-test. The significance level was taken as P < 0.05. Results: The comparative analysis between groups showed significant prolongation in latencies of P100 wave and N 145 wave in group II and reduced N75 - P100 amplitude in group II, though it was not statistically significant. Conclusion: It is concluded that the visual pathway is affected by diabetes and VEP changes are correlated with its duration. Therefore, VEPs can be used as a prognostic marker.

A Rare Cause of Paroxysmal Movement Disorder Associated with TBC1D24 Gene Mutation in Two Siblings.

A Rare Cause of Paroxysmal Movement Disorder Associated with TBC1D24 Gene Mutation in Two Siblings.

IMPLEMENTATION OF VISUAL EVOKED POTENTIAL FOR THE DETECTION OF PRERETINOPATHY AND PROGNOSTICATION IN DIABETES MELLITUS

Introduction: Diabetic Retinopathy (DR) is one of the complications of Diabetes Mellitus (DM) which affects the retinal blood vessels. It is one of the preeminent causes of blindness in the age group of 20 to 74 years albeit that visual loss due to it may be preventable by adequate glycaemic control. Visual Evoked Potential (VEP) can be used in diagnosis of retinal changes and ascertainment of prognosis can be done by it. Aim: To evaluate the ability of VEP in identifying preclinical neuro-degenerative changes in patients with diabetic preretinopathy by studying changes in VEP. Materials and Methods: This study comprises of 30 diabetic patients without retinopathy and 30 non diabetic controls. Patients were selected from the outpatient Department of Ophthalmology for the screening of DR. Latency of P100 was analysed because of its reliability and less inter-subject variability. Mean P100 wave latency of both groups were compared and analysis was done regarding any discrepancy in P100 wave latency with respect to the duration and the control of diabetes. Data was analysed using IBM-SPSS 27. Student's t- test was applied when two groups were compared whereas Analysis of Variance test was applied for multiple group comparisons. The p value <0.001 was considered statistically signicant. Results: There was signicant prolongation of P100 latency in diabetics without retinopathy. It was also observed that there was positive correlation between prolongation of P100 latency and duration of diabetes. Conclusion: VEP could be a better tool for the detection of very early retinal changes before any clinical evidence of retinopathy has set in. Adequate glycaemic control, dietary modication, appropriate dosage of medications could prevent the early development of retinopathy if done at this stage

Comparison of brainstem auditory evoked potentials and event-related potential-300 parameters among different severity levels of depression: A study on adult patients

Background: Depression, a serious mental health issue, linked to disruption in mood and cognitive abilities. One of the most crucial elements in the diagnosis and treatment of depression is its severity. Few researches have been conducted to determine the severity of depression on the brainstem and cognitive functioning. Therefore, this study focuses on evaluating brainstem auditory evoked potentials (BAEPs) and event-related potential (P300) parameters among depressive patients regarding severity levels (mild, moderate, and severe). Aims and Objective: The study aims to assess BAEPs and ERP (P300) parameters among different severity levels (mild, moderate, and severe) of depressive patients and compare the results. Materials and Methods: This cross-sectional study included 55 depressive patients divided into three groups fulfilling the diagnostic criteria of the diagnostic and statistical manual of mental disorders, fourth edition (DSM-IV) for major depressive disorder (MDD). The severity of depression was measured by the Hamilton Depression Rating Scale (HDRS). The BAEPs and ERP (P300) were recorded using NeuroStim-NS 21 and auditory oddball paradigm, respectively. Data were analyzed by one-way ANOVA followed by post hoc tests. P < 0.05 was considered statistically significant. Results: A significant difference was found among three groups of depression severity in BAEPs, wave I for the right ear and IPL I-III for the left ear. P300 wave latency was found to be significant between mild and moderate, and also between moderate and severe groups. Conclusion: The reported differences in BAEPs and ERP P300 latencies can be attributed to the delay in auditory processing of depressive individuals.

Physiological Challenges of Space Travel and Ground-Based Simulation Possibilities for Monitoring Brain Circulatory Changes: A Rheoencephalography Study

The functional integrity of brain perfusion and oxygen transport profoundly determines mental performance during military flight missions and spaceflight. Presently, at the selection phase of pilot candidates, there are no screening methods to evaluate cerebral circulation and its autonomous regulation (AR), meanwhile the pilot information processing capacity could be insufficient in dangerous flight situations with high mental workload or during high “head-to-foot” G loads. On-board ISS (International Space Station) and during deep-space missions circulatory changes can be evolved in the opposite direction due to the microgravity: blood shift toward the head-neck region can increase ICP (Intracranial Pressure) and tenfold increase of carbon-dioxide concentration can provoke complaints and disturbances in eye and brain blood circulation (Space Associated Neuro-Ocular Syndrome – SANS). The alteration of brain perfusion dynamics and oxygen utilisation was investigated on the head-down tilting table (HDT) test and in the hypobaric (low-pressure) chamber. We registered the brain regional pulse wave changes by the bioimpedance (Rheoencephalography – REG) on 19 volunteers in rest and after the breath-holding manoeuvre. We found that during the head-down tilt (HDT) position, the amplitude of the second peak of the REG pulse wave increased, like the ICP pulse wave, being an unfavourable sign for intracranial pressure increase in clinical cases. Manual readings resulted in significant differences during HDT between the female (P = 0.0007) and male (P < 0.0001) groups. With automated analysis, the increase in REG P2 wave was significant, and the ratio was 4/5 (80%) for women and 10/14 (71%) for men. The newly written automatic program script was able to detect this in 92% of the cases. The calculated values detected the state of cerebral circulatory autoregulation and the identity between the male and female groups. Based on this result and previous REG correlation studies, it can be concluded that REG could be used to monitor fighter pilots, astronauts, and neurocritical care patients in real-time as emergency alert in the transitory cessation of brain perfusion.

Evaluation of retinal function and morphology in isoametropic amblyopia.

To observe the photoreceptor anomalies in cases of ametropic amblyopia. A prospective study with 25 isoametropic amblyopic children in the age group of 5-14 years and 25 age-matched controls was done. Examination included refraction, best-corrected visual acuity (BCVA), and color vision. Adaptive optics (AO) and multifocal electroretinogram (mf-ERG) were done to assess the anatomy and function of photoreceptors. The subgroup analysis of the improved and non-improved groups was done. The mean cone density in cases and control in the superior, temporal, and nasal quadrants was respectively as follows (21640 ± 5713, 24040 ± 3386, P = 0.01) (19755 ± 6282, 21832 ± 2911, P = 0.03) (19897 ± 5418, 22171 ± 3660, P = 0.01) (20768 ± 4799, 22819 ± 3241, P = 0.01). The amplitude of N1 wave and P1 wave in cases was significantly low compared to the controls. Cases with subnormal color vision had reduced BCVA (0.55 ± 0.018) in comparison to the children with normal response (0.350 ± 0.014). Cone density was also significantly reduced in children with subnormal color vision. Sixteen out of 25 cases showed BCVA improvement with spectacles. Baseline cone density was found to be significantly higher in the improved group. There was no correlation between BCVA and AO parameters. Patients with ametropic amblyopia show subnormal photoreceptor properties than controls. Low cone density may be associated with defective color vision and poor prognosis in these cases.

Scattering of Plane Waves by Cylindrical Cavity in Unsaturated Poroelastic Medium

The scattering of elastic waves by underground cavities is an active research topic for its broad applications in various fields, such as earthquake engineering, the blast resistance of underground structures, geophysical exploration, etc. In most previous studies, the sounding medium was treated as an ideal elastic medium or a saturated poroelastic medium. The understanding of the scattering of elastic waves by cavities in unsaturated porous media is limited. In this study, the scattering of plane P1 waves and SV waves by a cavity with a permeable surface in an infinite unsaturated porous medium is solved by the wave function expansion method. The dynamic stress concentration at the cavity surface is investigated by taking P1 wave incidence, for example. Numerical results illustrate that the scattering of plane waves around the cavity strongly depends on the frequency of the incident waves, and the saturation, Poisson’s ratio, and porosity of the surrounding medium.

Short-term transcutaneous trigeminal nerve stimulation does not affect visual oddball task and paired-click paradigm ERP responses in healthy volunteers

Recent research suggests that transcutaneous trigeminal nerve stimulation (TNS) may positively affect cognitive function. However, no clear-cut evidence is available yet, since the majority of it derives from clinical studies, and the few data on healthy subjects show inconsistent results. In this study, we report the effects of short-term TNS on event-related potentials (ERP) recorded during the administration of a simple visual oddball task and a paired-click paradigm, both considered useful for studying brain information processing functions. Thirty-two healthy subjects underwent EEG recording before and after 20min of sham- or real-TNS, delivered bilaterally to the infraorbital nerve. The amplitude and latency of P200 and P300 waves in the simple visual oddball task and P50, N100 and P200 waves in the paired-click paradigm were measured before and after treatment. Our results show that short-term TNS did not alter any of the ERP parameters measured, suggesting that in healthy subjects, short-term TNS may not affect brain processes involved in cognitive functions such as pre-attentional processes, early allocation of attention and immediate memory. The perspective of having an effective, non-pharmacological, non-invasive, and safe treatment option for cognitive decline is particularly appealing; therefore, more research on the positive effects on cognition of TNS is definitely needed.

Analysis of Retinal Structure and Electrophysiological Function in Visual Snow Syndrome: An Exploratory Case Series.

Visual snow (VS) is a rare but distressing phenomenon of persistent granular or pixelated visual distortions that may occur in isolation or as a component of visual snow syndrome (VSS). The current understanding of VS pathogenesis, including the role of retinal involvement structurally and functionally, is limited. The objective of this study is to investigate retinal structural and electrophysiological abnormalities in VS. This retrospective case series included 8 subjects (7 with VSS and 1 with isolated VS). Patients with other ocular and neurologic diseases were excluded. Data were assessed from automated perimetry, optical coherence tomography (OCT), visual evoked potential (VEP), and full-field electroretinography (ffERG) testing. The VEP and ffERG data of visual snow subjects were compared with age- and sex-matched control subjects for statistical significance. The mean age of the cohort was 29.4 years (SD = ±5.3) with 50% gender split. The mean age of VS onset was 24.2 years (SD = ±3.8). All subjects had normal visual acuity, color vision, brain MRI, automated perimetry, OCT parameters (peripapillary retinal nerve fiber layer and macular ganglion cell layer thickness), and P100 and N135 wave pattern on VEP. Compared with controls, VS subjects had a greater mean b-wave amplitude in response to light-adapted 3.0 stimuli ( t test; P = 0.035 right eye and P = 0.072 left eye), greater mean light-adapted 3.0 flicker amplitude ( t test; P = 0.028 right eye P = 0.166 left eye) and greater b-wave amplitude in response to dark-adapted 10.0 stimuli ( t test; P = 0.102 right eye; P = 0.017 left eye) on ERG. Patients with VS and VSS have normal retinal structure, but abnormal electrophysiology compared with control subjects. The increased b-wave and flicker amplitudes observed with ffERG suggest increased responsiveness of the rod and cone photoreceptors and may contribute to VS pathophysiology.

Macular function in patients with medium myopia

PurposeThis work aims at assessing whether electrophysiological functional changes in the macular region appear in medium myopia, even in the presence of a normal macular OCT scan and how axial length correlates with macular OCT parameters in medium myopia.MethodsThe study included right eyes of 17 patients with myopia of medium degree (SE < − 6D to > − 3D). Control group consisted of 20 eyes of patients of age and sex that matched healthy controls with normal macular and optic nerve OCT results and normal axial length. Full ophthalmic examination (the distance best-corrected visual acuity, intraocular pressure, refractive error, the anterior and posterior segment of the eye in a slit lamp, the axial length of the eyeball) with OCT of the macular and optic disk and the PERG test were performed in the study and control groups. Only the patients with normal ophthalmic and OCT examination results were qualified. The interview covering questions on risk factors of myopia onset and progression such as prematurity, family history of myopia was carried out in both groups. In myopic group, the question relating to time of near work was also asked. Study and control groups were tested with the use of Shapiro–Wilk, Mann–Whitney, Student’s t test, Pearson and Spearman's rank correlation tests.ResultsAL was significantly longer in myopia group (p < 0.01), and SE value was lower (p < 0.01). Longer implicit time of P50 was found in the study group, but amplitudes of P50 and N95 waves were not significantly reduced (p < 0.05). AL showed correlations with P50 implicit time (p < 0.05) and with reduction in retinal fiber nerve layer and ganglion cells and inner plexus layer (p < 0.05).ConclusionPatients with myopia of medium degree have a dysfunction of retinal cone system of the macular region even when OCT scans show no abnormalities. Elongation of AL correlates with reduction in retinal fiber nerve layer and ganglion cells and inner plexus layer. Longitudinal follow-up studies may answer the question whether this increase in implicit time may be indicative of a faster myopia progression or of myopic retinal pathology, i.e., whether it may help to determine which patient would benefit from earlier or more intensive management of myopia progression.

Reliability of electroencephalogram indicator and event related potential in subacute stroke

Cognitive impairment is observed in 12% to 56% of stroke patients, and screening for cognitive impairment is often complex and time-consuming, with results dependent on patient compliance. Therefore, there is a need for an objective method to assess cognitive impairment regardless of patient compliance. Objective evaluation methods include electroencephalogram (EEG) and event-related potential (ERP). This study was conducted to assess intra-tester reliability of resting EEG-based spectral features and auditory/visual P300 latency/amplitude in patients with subacute ischemic stroke. Twenty patients with subacute ischemic stroke were included in the study. The resting EEG and P300 wave using an auditory and visual oddball paradigm were measured at baseline and once again in 24 hours. The following electrode positions (10-20 system) were constantly recorded: F3 (Frontal), Fz, F4, C3 (Central), Cz, C4, P3 (Parietal), Pz, P4. DAR (delta/alpha ratio) and BSI (brain symmetry index) were determined using EEG data. F3 and F4, C3 and C4 and P3 and P4 were switched according to the stroke side and classified as affected hemisphere (AH) and unaffected hemisphere (UH) after the evaluation. In ERP, the amplitude and latency of P300 were obtained. In reliability analysis of EEG-based spectral characteristics, significant reliability was observed for DAR (ICC = 0.447), BSldir (ICC = 0.713) and BSIdirtheta (ICC = 0.724) (Table 4). DAR was showed a poor ICC level, and BSIdir and BSIdirtheta had a moderate ICC level. Visual P300 latency showed excellent intraclass correlation coefficient (ICC) in several montages (PUH = 0.972, Pz = 0.945). In 6 montages, auditory P300 latency was reliable, while in 9 montages, visual P300 latency was reliable. In 4 montages, auditory P300 amplitude was reliable, while visual P300 amplitude was reliable in 7. The visual P300 was more reliable than the auditory P300. The ICC values for P300 latency were greater than those for amplitude. Therefore, when ERP is performed on subacute stroke patients, visual has higher reliability than auditory.

Event-Related Potential Correlates of Learning to Produce Novel Foreign Phonemes.

Learning to pronounce a foreign phoneme requires an individual to acquire a motor program that enables the reproduction of the new acoustic target sound. This process is largely based on the use of auditory feedback to detect pronunciation errors to adjust vocalization. While early auditory evoked neural activity underlies automatic detection and adaptation to vocalization errors, little is known about the neural correlates of acquiring novel speech targets. To investigate the neural processes that mediate the learning of foreign phoneme pronunciation, we recorded event-related potentials when participants (N = 19) pronounced native or foreign phonemes. Behavioral results indicated that the participants' pronunciation of the foreign phoneme improved during the experiment. Early auditory responses (N1 and P2 waves, approximately 85-290 ms after the sound onset) revealed no differences between foreign and native phonemes. In contrast, the amplitude of the frontocentrally distributed late slow wave (LSW, 320-440 ms) was modulated by the pronunciation of the foreign phonemes, and the effect changed during the experiment, paralleling the improvement in pronunciation. These results suggest that the LSW may reflect higher-order monitoring processes that signal successful pronunciation and help learn novel phonemes.

Association between P300 parameters and cognitive function in people with diabetic neuropathy.

The purpose of this study was to investigate the association between event-related potential (ERP) P300 with cognitive function in people with diabetic peripheral neuropathy (DPN). We performed a cross-sectional analysis of 19 type 2 diabetes mellitus (T2DM) patients, aged 18 and older with DPN. The participants were assessed for neuropathy, cognitive function, & dual-task performance. DPN was examined via the administration of diabetic neuropathy symptom score (DNSS) and vibration perception threshold (VPT). Cognitive dysfunction was evaluated using Mini-mental state examination (MMSE), trail making test-B (TMT-B), and ERP P300 wave latency & amplitude. For assessing dual-task performance, the dual-task cost (DTC) was calculated using the timed-up and go (TUG) test and TUG with dual task (TUG-DT). P300 latency was linearly related to TMT-B (R = 0.31, p = 0.01) and DTC (R = 0.22, p = 0.04). A similar trend was observed in TMT-B (R = 0.13, p = 0.04) & DTC (R =0 .67, p = 0.001) with respect to P300 amplitude. MMSE did not relate with P300 latency (R = 0.14, p = 0.58) & amplitude (R = 0.63, p = .44). P300 latency and amplitude are associated with cognitive function and DTC of individuals with DPN.

Visual evoked potentials as a method for the prospective assessment of tacrolimus neurotoxicity in patients after kidney transplantation

IntroductionNeurotoxicity, including optic nerve injury, is one of the most common adverse effects of tacrolimus, the principal calcineurin inhibitor used after kidney transplantation (KTx). The electrophysiologic measurements of both pattern visual evoked potentials (PVEP) and flash visual evoked potentials (FVEP) are valuable when drug-induced optic neuropathy is suspected.ObjectivesTo determine whether VEP measurement is a sensitive and repeatable method for monitoring tacrolimus neurotoxicity.Material and methodsThis prospective study focused on 35 patients (20 M, 15F, 69 eyes, mean age 43 ± 11 years) who were at a median of 3.0 (IQR, 2.2–3.7) months after KTx at the time of the initial VEP evaluation and were treated with tacrolimus since KTx. The follow-up VEP examination was done after a median of 24 (22–27) months (both VEP measurements followed the ISCEV standards). The P100 wave latency and amplitude for the 1° and 15’ PVEP simulations, and the P2 wave latency and amplitude for the FVEP were analyzed.ResultsFor the 1° checks, the P100 wave latency and amplitude values were significantly worse in the follow-up examination compared to the early post-transplant time-point. Independent associations between FVEP parameters and the tacrolimus blood trough level were observed in the follow-up examination but not at the early post-transplant period. The P2 wave latency correlated with the tacrolimus trough level only in patients treated with the twice-daily, but not the once-daily, tacrolimus formulation. The brain derived neurotrophic factor (BDNF) level correlated with the P100 (15’) latency (R = 0.499; p = 0.005) and the P2 latency (R = 0.409; p = 0.025) only in patients treated with the once-daily, but not the twice-daily, tacrolimus formulation.ConclusionThe observations in this study may support the rationale for the use of VEP measurements as non-invasive monitoring of subclinical tacrolimus neurotoxicity.

Premorbid factors of early post-stroke cognitive impairment

The aim of this study is to identify and substantiate early cognitive dysfunction in patients with brain damage in the acute period of ischemic stroke.Materials and research methods. The study included 140 elderly patients. The main group included 70 patients of Vascular Surgery Center with a diagnosis of ischemic stroke in the carotid pool, the control group consisted of 70 outpatients. Cognitive function and psycho-emotional background were assessed using the Montreal Cognitive Function Scale, tests for kinetic, constructive and ideation praxis, the Stroop test, the Boston Naming Test, the apathy rating scale, the Hospital Anxiety and Depression Scale, and the MFI-20 asthenia scale. Assessment of neuroimaging parameters was carried out usingcomputed tomography. Assessment of long-latency acoustic endogenous evoked potential P300 using the «oddball active» paradigm technique was used for neurophysiological examination.Research results. Ischemic stroke was more often detected in the parietal, frontal lobes and basal ganglia. Moderate cognitive impairment was detected in 57.5% of patients with stroke and 27.5% of the control group. Dementia was diagnosed in 30% of patients in the main group and 5% of the control group. In patients with IS indicators characterizing the executive function, praxis, speech, attention, memory, depression, and apathy were statistically significantly lower comparing with the control group. The analysis of neurophysiological data revealed a statistically significant prolongation of the latency of the P300 wave in all leads and a decrease in the amplitude of the P300 peak in leads Cz and C3 in patients of the main group. Conclusion. Within the framework of this study, significant factors in the development of early post-stroke cognitive impairment were established. Dysfunction in attention, executive function, episodic memory, and speech is the result of a combination of causes directly related to cerebrovascular disease and pre-stroke factors. The evoked potential method reflects the degree of cognitive decline and can be used as a method for assessing the effectiveness of cognitive rehabilitation in stroke patients.

PEELED INTERNAL LIMITING MEMBRANE REPOSITION FOR IDIOPATHIC MACULAR HOLES: A Pilot Randomized Controlled Trial.

To compare the functional and anatomical outcomes of peeled internal limiting membrane reposition and traditional internal limiting membrane peeling for the treatment of idiopathic macular hole. This is a randomized, single-center, and double-blinded, pilot, controlled trial. Of the 30 patients enrolled, 27 (13 in Group 1 and 14 in Group 2) were included in the primary analysis (22 women [81.5%]; mean [SD] age, 61.7 [6.8] years). The BCVA was 0.23 ± 0.18 logMAR in the reposition group and 0.44 ± 0.24 logMAR in the peeling group at 6 months postoperatively (P = 0.02). The primary MH closure rate is 86.7% in the reposition group and 93.3% in the peeling group (P = 0.60). The range of the inner retinal dimpling was significantly lower in the reposition group at 6 months postoperatively (P < 0.0001). The thickness of the full parafovea (P = 0.0092), inner parafovea (P = 0.0007), inner perifovea (P = 0.0044), and outer fovea (P = 0.0392) was significantly greater in the reposition group than that in the peeling group at 6 months postoperatively. The sensitivity threshold and mfERG P1 wave amplitude density in rings one, four, and five were higher in the reposition group than in the peeling group at 6 months postoperatively. Our findings suggest that the novel technique of peeled internal limiting membrane reposition has advantages over the traditional internal limiting membrane peeling in better microstructural outcomes of inner retina and functional recoveries. Furthermore, larger RCT studies are warranted.

Leveraging Deep Learning Techniques to Improve P300-Based Brain Computer Interfaces.

Brain-Computer Interface (BCI) has become an established technology to interconnect a human brain and an external device. One of the most popular protocols for BCI is based on the extraction of the so-called P300 wave from electroencephalography (EEG) recordings. P300 wave is an event-related potential with a latency of 300 ms after the onset of a rare stimulus. In this paper, we used deep learning architectures, namely convolutional neural networks (CNNs), to improve P300-based BCIs. We propose a novel BCI classifier, called P3CNET, that improved P300 classification accuracy performances of the best state-of-the-art classifier. In addition, we explored pre-processing and training choices that improved the usability of BCI systems. For the pre-processing of EEG data, we explored the optimal signal interval that would improve classification accuracies. Then, we explored the minimum number of calibration sessions to balance higher accuracy and shorter calibration time. To improve the explainability of deep learning architectures, we analyzed the saliency maps of the input EEG signal leading to a correct P300 classification, and we observed that the elimination of less informative electrode channels from the data did not result in better accuracy. All the methodologies and explorations were performed and validated on two different CNN classifiers, demonstrating the generalizability of the obtained results. Finally, we showed the advantages given by transfer learning when using the proposed novel architecture on other P300 datasets. The presented architectures and practical suggestions can be used by BCI practitioners to improve its effectiveness.

Comparison of Amplitude and Implicit Time Between Jet Electrode, Dencott Electrode and Dawson-Trick-Litzkow Electrode in Multifocal Electroretinography Examination in Adult

Introduction: Multifocal electroretinography (ERG) is an examination which measures retinal electrical activity as a response to lighting stimulus and allows simultaneous recording in many topographic locations. Various electrodes have been developed to balance examination accuracy and also patients’ comfort. The objective of this study is to establish normal values of multifocal ERG and to compare the values and the comfort level using Jet, Dencott and DTL electrode in Indonesian Adult.&#x0D; Methods: Through convenient sampling 49 normal Indonesian subjects between 19 and 49 years old were selected. Multifocal ERG amplitudes and implicit time values were measured according to recommendation by the ISCEV. Evaluation consisted of N1 and P1 wave in ring 1 to 5. after the examination, all subjects filled in a questionnaire about comfort level, adopted from the visual analog scale.&#x0D; Result: We observed a statistically significant difference in multifocal ERG normal values between electrode with higher wave amplitudes and longer implicit time in Jet and Dencott electrodes compared to DTL electrodes. Jet and DTL electrodes are more comfortable than Dencott electrodes for Indonesian adults in multifocal ERG.&#x0D; Conclusion: DTL electrodes give the lowest wave amplitude and the shortest implicit time and are the most comfortable electrode compared to Jet and Dencott electrodes, in multifocal ERG in Indonesian adults.

Evaluation of visual evoked potentials in dysthyroid optic neuropathy

ABSTRACT Purpose To evaluate the findings of visual evoked potentials (VEP) in patients with dysthyroid optic neuropathy (DON). Methods In this observational, cross-sectional study 40 eyes (22 patients) with a diagnosis of DON were included. Results We discovered that in 16 out of 37 eyes with pattern-VEP (p-VEP), the latency of P100 wave was normal in spite of having a diagnosis of DON. The same pattern was also observed in the measurement of the amplitude of P100 wave: in 28 out of 37 eyes with p-VEP the amplitudes were observed as normal. In 3 eyes of 3 patients p-VEP showed no response, therefore a flash-VEP (f-VEP) was performed. Flash-VEPs of those patients indicated a prolonged P100 latency with a reduced amplitude. The sensitivity of abnormal P100 latency was 56.8% (95%CI 39.5–72.9%); and that of reduced P100 amplitude was 24.3% (95%CI 11.8–41.2%). Also, in 40 eyes color vision test by Arden was performed. In 36 eyes (20 patients) the tritan value was pathological (based on a threshold of ≥8%). Conclusion According our data, VEP seems to have a limited potential especially in patients with a good best-corrected visual acuity (BCVA ≤0.2 LogMAR) for identifying the optic nerve involvement. The fact that P100 latency and amplitude were normal even in cases with an optic nerve swelling makes us question the usefulness of the VEP for diagnosing cases of DON in daily clinical life.

Theoretical study of S wave passing through a double-layer wave impeding block in the unsaturated soil

In foundation vibration control, the multi-layer isolation barrier has a good vibration isolation effect due to its ability to block the propagation of elastic waves multiple times. In this paper, using the double-layer wave impeding block(WIB) as an example, the calculation model of a double-layer WIB as a vibration isolation barrier in the unsaturated soil foundation is established. The analytical solution of the transmission/reflection amplitude ratio when the S wave passes through the double-layer WIB in the unsaturated soil foundation is calculated by using the Helmholtz vector decomposition theorem. In addition, the influence of parameters such as the wave impedance ratio, saturation, shear modulus and density on the vibration isolation performance of the WIB are analyzed by numerical examples. The results show that the wave impedance ratio, shear modulus and density of the WIB material have a significant influence on the transmission/reflection amplitude ratio. Saturation has little effect on the transmission/reflection amplitude ratio of P1 and S waves but has a great effect on the amplitude ratio of P2 and P3 waves. The best vibration isolation effect can be obtained by selecting the optimal wave impedance ratio and shear modulus of the double-layer WIB material.