Normative values of visual evoked potential in adults

Purpose:Visual evoked potentials (VEP) are used to determine the function of visual pathway from the optic nerve to visual cortex. Various factors may affect VEP response, viz., technical and environmental. The aim of this study is to obtain the normative value of VEP latency and amplitude parameters in adulthood in Indonesia, as well as the relationship of height, weight, body mass index (BMI), head circumference, and visual acuity with the variety of latency and amplitude values of VEP parameters.Methods:It is a cross-sectional study on 120 healthy subjects consisting of 60 males and 60 females between 18 and 65 years old. Height, weight, BMI, head circumference, and visual acuity were measured and continued with VEP examination using a 26′ checkerboard pattern on the left and right eyes alternately. All data were collected and analyzed with the Shapiro–Wilk test using statistical software R version 3.5.2.Results:Mean value of P100 latency (interocular latency) of left and right eye were 104.6 ± 3.4 ms and 104.1 ± 3.4 ms, respectively, as well as 9.8 ± 4.7 μV and 10.3 ± 5.4 μV for the amplitude. There was no significant difference between the male and female group, as well as on the age group. Female significantly exhibited a higher P100 amplitude than male. The greater the age, the lower amplitude of P100 significantly.Conclusion:Gender and age do not affect the P100 latency value but only affect P100 amplitude. Height, weight, BMI, head circumference, and visual acuity also do not affect the P100 latency and amplitude.     

弱视儿童非弱视眼的视觉诱发电位分析

双８４例儿童正常视力眼的视觉诱发电位（ｖｉｓｕａｌ ｅｖｏｋｅｄ ｐｏｔｅｎｔｉａｌ，ＶＥＰ）进行了分析，其中正常儿童２０人，屈光参差性弱视儿童２８人，治愈的屈光参差性弱视儿童８人，单卵双生子８对，双卵双生子６对。结果表明：弱视的对侧眼及已治愈的弱视眼，尽管视力完全正常，但ＶＥＰ仍表现异常，以Ｐ１００波潜伏期延长明显；双生子中遗传物质相同的单卵双生子，其视力正常眼与弱视眼间的ＶＥＰ差异无显著性意义     

视觉诱发电位在弱视中的应用

弱视是儿童的常见眼病,是眼科医师研究的重要课题。不同类型视觉诱发电位的发展和应用为弱视的早期诊断、治疗及其发病机制的研究提供了一条充满希望的新途径。     

扫描翻转图像视觉诱发电位视力在视功能损害疾病中的应用

目的:了解扫描翻转图像视觉诱发电位视力 (SPVER视力 )在视神经损伤和视野改变疾病中应用的准确性。方法 :比较 5 1例 6 6眼有不同视神经损伤和视野改变疾病的SPVER视力和对数视力表视力。在SPVER视力的测定中我们用了 8个不同空间频率的光栅条纹连续扫描 ,所得的数据经离散傅立叶分析后 ,获得振幅 空间频率曲线 ,并通过外推法估计其视力。结果 :5 1例 6 6眼中 ,视力表视力在 0 0 8～ 1 2 ,SPVER视力在 2 0 /2 0 0～ 2 0 /2 0 ,两者的总体相关系数为 0 6 2 2。其中不同疾病两种视力的相关系数有较大的区别 ,从中浆的r =0 80 7到外伤性视神经病变的r =0 2 82。结论 :SPVEP视力与视力表视力有良好的相关性 ,它是一项客观、快速的视力测定方法 ,但同时应注意到各种疾病引起视神经损伤后对SPVER视力可能会带来较大的误差 ,因此在得出结论时应对疾病进行综合考虑     

显微镜下斜视矫正术对斜视患者视觉恢复及并发症的影响

目的探讨微镜下斜视矫正术对斜视患者视觉恢复及并发症的影响。方法选取2017年3月-2018年7月在我院进行治疗的斜视患者78例,参照随机数字表法的分组方式,分为传统组和显微组,每组各39例。传统组患者采用传统手术治疗,显微组患者采用显微镜下斜视矫正术进行治疗,观察分析两组患者临床指标、视觉恢复状况及不良反应现象。结果显微组患者手术时间及术中出血量显著低于传统组患者,差异有统计学意义(P<0.05);显微组患者视觉恢复状况显著高于传统组患者,差异有统计学意义(P<0.05);显微组患者不良反应发生率显著低于传统组患者,差异有统计学意义(P<0.05)。结论采用显微镜下斜视矫正术治疗可改善斜视患者临床症状,促进视觉恢复,且产生的不良反应较少,安全性较高。     

视力客观检测方法的研究

目的研究用视觉诱发电位（ｖｉｓｕａｌｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ,ＶＥＰ）作为视力客观检测的可行性。方法对４０只视力不等的患眼和５０只正常眼,分别记录用不同大小方格（８°、４°、２°、１°、３０、１５和６）刺激时的ＶＥＰ波形。结果患眼组和正常组Ｐ１００振幅及潜时在统计学上有显著性差异。视力与能诱发出波形的最小方格间有明显关系：最小方格为６、１５、３０和１°,平均视力分别为１．１３,０．６２,０．１８和０．０７。视力与Ｐ１００振幅呈正相关,与潜时呈负相关。结论用诱发出ＶＥＰ波形的最小方格大小可估计患者的视力范围     

The effect of low-dose interferon treatment on visual evoked potentials

Patients suffering from chronic viral hepatitis, treated with interferon alpha-2b in a dose of 3 million units trice weekly subcutaneously, were studied. The influence of interferon on the optic nerve was evaluated by measuring the P100 implicit time of the visual evoked potentials. The results before the treatment were compared with those after 6 and 12 months of therapy, as well as with those of normal subjects. There were statisticaly significant differences between the groups. Furthermore, in 10 of 56 eyes (17.8%) after 6 months of treatment, and 8 of 22 eyes (36.3%) after 12 months of treatment, the P100 was abnormally delayed. The long term neurovisual effects of low-dose interferon are currently under investigation.     

正常人周边区与中央区视觉诱发电位的变化规律

目的探讨正常人周边区与中央区图形翻转视觉诱发电位(visualevokedpotential,VEP)的变化规律。方法以图形翻转VEP作为研究工具研究18例正常人30°以外的上方、下方、鼻侧、颞侧4个方向周边区与中央区在Oz导程对比的图形VEP的波形特征。结果正常人的周边VEP在这4个方向上的N75、P100的潜伏期均随空间频率的增大而增大;N75-P100的峰值却有一个最适的空间频率,即N75-P100峰值只在这个最适空间频率下最大;另外周边区VEPN75、P100的潜伏期均较中央区VEPN75、P100的潜伏期明显延长,周边区VEPN57-P100的峰值均较中央区VEPN75-P100的峰值低。结论视网膜不同区域在枕叶投射的部位决定VEP的潜伏期。     

The effects of physostigmine on the response characteristics of the cat visual evoked potential

Steady—state pattern visual evoked potentials were recorded from the surface of the cat primary visual cortex before and after the intravenous administration of physostigmine, an agent that blocks the enzyme responsible for the breakdown of synaptically released acetylcholine. Under pentobarbital anesthesia, physostigmine increased the amplitude and changed the phase of the second response harmonic of the visual evoked potential, whereas the amplitude and phase of the fourth harmonic were not affected. These effects persisted for 15 to 45 minutes and were blocked by prior treatment with scopolamine or atropine. In addition, scopolamine or atropine administered 5 to 10 minutes after physostigmine returned the visual evoked potential to the baseline state. In comparison, when nitrous oxide was used, physostigmine caused a marked reduction in visual evoked potential amplitude, an effect that was reversed by subsequent atropine. These results indicate that the cholinergic system influences the visual evoked potential via a muscarinic pathway and that this influence is strongly affected by the anesthetic regimen used.Abbreviations Ach acetylcholine - LGN lateral geniculate nucleus     

Influence of callosal transfer on visual cortical evoked response and the implication in the development of a visual prosthesis

Background The development of a visual prosthesis has been limited by an incomplete understanding of functional changes of the visual cortex accompanying deafferentation. In particular, the role of the corpus callosum in modulating these changes has not been fully evaluated. Recent experimental evidence suggests that through synaptic modulation, short-term (4–5 days) visual deafferentation can induce plastic changes in the visual cortex, leading to adaptive enhancement of residual visual input. We therefore investigated whether a compensatory rerouting of visual information can occur via the indirect transcallosal linkage after deafferentation and the influence of this interhemispheric communication on the visual evoked response of each hemisphere. Methods In albino rabbits, misrouting of uncrossed optic fibres reduces ipsilateral input to a negligible degree. We thus took advantage of this congenital anomaly to model unilateral cortical and ocular deafferentation by eliminating visual input from one eye and recorded the visual evoked potential (VEP) from the intact eye. Results In keeping with the chiasmal anomaly, no VEP was elicited from the hemisphere ipsilateral to the intact eye. This remained unchanged following unilateral visual deafferentation. The amplitude and latency of the VEP in the fellow hemisphere, however, were significantly decreased in the deafferented animals. Conclusion Our data suggest that callosal linkage does not contribute to visual evoked responses and this is not changed after short-term deafferentation. The decrease in amplitude and latency of evoked responses in the hemisphere ipsilateral to the treated eye, however, confirms the facilitatory role of callosal transfer. This observation highlights the importance of bicortical stimulation in the future design of a cortical visual prosthesis. The authors have no financial relationship with any organisation concerning this research project. The authors have full control of all primary data and we agree to allow Graefe’s Archive for Clinical and Experimental Ophthalmology to review our data upon request.     

Contrast sensitivity differences between strabismic and anisometropic amblyopia: objective correlate by means of visual evoked responses

The visual evoked response transfer function of amblyopic subjects was studied. Strabismic amblyopes showed abnormalities only in the high spatial frequency range. Anisometropic amblyopes on the contrary, showed an abnormal function both in the low and high spatial frequency range. This is an objective correlate of functional differences between strabismic and anisometropic amblyopes.     

弱视儿童双眼总和视觉诱发电位变化的研究

目的探讨弱视儿童双眼视功能及总和图形视觉诱发电位（P-VEP）反应的特点,评估总和P-VEP反应对双眼视觉功能检测的意义。方法选取80名正常儿童和在南昌大学附属第二医院儿童眼科确诊的远视性弱视儿童151例,进行双眼总和P-VEP检查,分析总和P-VEP反应的特点。正常儿童与弱视儿童的人口基线学特征经统计学分析差异无统计学意义。P-VEP检查方法和刺激条件的选择参照吴乐正等的方法,记录电极的放置按照视觉电生理国际标准化的要求。视力检查采用国际标准视力表,双眼视觉功能检查采用Titmus立体图、同视机三级画片。P-VEP检测结果以双眼反应/单眼反应（B/M）比值作为评价指标。结果弱视组儿童总和P-VEP反应低于正常对照组（t=10.75,P〈0.01）;不同程度弱视组的B/M值随弱视的严重程度明显减低（F=10.93,P〈0.01）;无同时视者总和P-VEP与有同时视者比较,差异有统计学意义（t=7.835,P〈0.01）。结论总和P-VEP反应作为一种客观指标,可以反映弱视儿童的双眼视功能状况,对其双眼视功能的评价具有一定的价值。     

The value of VEP in the diagnosis and post-operative monitoring of meningioma

Meningiomas are the most frequently reported primary intracranial neoplasms. At first they usually cause unilateral visual loss but eventually result in a bilateral loss of vision. Depending upon the size and location of the tumour, the ocular signs and symptoms of meningiomas may include visual field abnormalities, optic atrophy, papilledema, diplopia and proptosis. This case report highlights the value of visual evoked potentials (VEP) in a patient with unexplained bilateral optic atrophy and a progressive loss of vision over 2 years. As a result of a delayed response in the VEP recorded from the right eye, a compressive lesion of the optic nerve was suspected. That prompted the referring ophthalmologist to request a MRI scan which led to the diagnosis of meningioma. Following the subtotal removal of the suprasellar meningioma, the remaining vision in the right eye improved and the latency of the VEP returned to the normal range. However, the VEP from the blind eye (left) did not show any measurable response either pre- or postoperatively. Experience with this patient suggests that early recognition of optic nerve compression is vital to an optimal outcome and the VEP technique, which is much more cost-effective than MRI, is clinically useful for detecting such compressive lesions.     

图形视觉诱发电位记录双眼形觉剥夺成年大鼠视皮层可塑性的研究

背景视觉诱发电位（VEP）是记录大鼠成年后视皮层可塑性变化的主要功能性评价指标,单眼形觉剥夺（MD）模型是研究哺乳动物视皮层可塑性存在与否的经典模型,应用上述技术研究成年大鼠模型眼优势移动情况对研究弱视眼的治疗时机有重要的意义。目的应用图形视觉诱发电位（PVEP）的方法评估各周龄正常大鼠和双眼形觉剥夺成年大鼠视皮层可塑性的变化。方法健康SPF级Long—Evens大鼠按其出生后周龄分为3、4、5、6、7周组,3、4、5、6周组每组9只,7周组36只。各周龄大鼠左眼分别遮盖3、5、7d,分别于上述时间点记录大鼠左眼、右眼PVEPP。波振幅,观察左右眼遮盖前后P100波振幅变化,评价眼优势移动情况,确定大鼠视皮层可塑性结束的周龄。7周龄SPF级Long—Evens大鼠行双眼PVEP检测,利用眼睑缝合法分别行双眼形觉剥夺7、10、14d,然后打开右眼,分别于3、5、7d后再打开左眼,再次行双眼PVEP检测,观察眼优势是否发生移动。结果出生后3周龄大鼠,左眼遮盖后3—7d,左眼P100波振幅逐渐下降,而右眼P100波振幅逐渐升高,与术前比较差异均有统计学意义（P〈0．01）。出生后6周龄大鼠左眼遮盖3d,左眼、右眼P100波振幅与术前相比差异均无统计学意义（P〉0．05）;但左眼遮盖后5d、7d,左眼P100波振幅明显下降,右眼P100波振幅明显升高,差异均有统计学意义（P〈0．01）。出生后7周龄大鼠左眼遮盖后3～7d,左眼、右眼大鼠P100波振幅与遮盖前相比,差异均无统计学意义（P〉0．05）。3、4、5周龄大鼠术前C／I比值分别为2．69~0．45、2．58±0．41和2．62±0．32,左眼遮盖后的对侧眼振幅值／同侧眼振幅值（C／I）比值分别为1．07±0．15、1．16±0．16和1．14±0．15,差异均有统计学意义（P〈0．01）,但6周龄、7周龄大鼠C／I比值分别为2．80±0．48和2．59±0．36,与术前（2．90±0．46）相比差异均无统计学意义（P〉0．05）,视皮层可塑性消失。7周龄大鼠行双眼形觉剥夺14d,再行左眼遮盖3d后C／I比值较术前降低,差异有统计学意义（1．33±0．18口s2．70±0．45,P〈0．01）,视皮层可塑性被再激活。结论PVEP可以在大鼠动物模型上进行记录,并可以作为检测视皮层眼优势移动的指标;双眼形觉剥夺模型可以再激活成年大鼠视皮层可塑性。     

眼外伤后视力的视觉诱发电位评估

目的:研究眼外伤后189眼的视觉诱发电位资料,探讨将诱发电位技术应用于视力评估的可行性及方法。方法:全部受检对象为志愿合作者,使用国际标准视力表对其视力随机筛查、盲测并分组,以刺激模式空间频率、P100波幅和潜伏期作为检测指标,探索最小空间频率,研究其与视力的对应关系,分析最小空间频率条件下P100波幅和潜伏期与视力的关系,确定应用视觉诱发电位技术评估视力的方法,比较受检眼的视力表筛查与视觉诱发电位评估结果。结果:最小空间频率22’,11’,5’及3’所对应的视力分别为0.1~0.2,0.3~0.5,0.6~1.0及1.2~1.5,不同视力P100波幅存在显著性差异,而P100潜伏期却未表现出明显差异,结合最小空间频率及P100波幅对全部受检眼视力的视觉诱发电位随机评估,其结果与国际标准视力表筛查结果比较无显著性差异。结论:应用视觉诱发电位技术可对志愿合作者的视力水平进行客观评估。     

Comparison of visual function in pigmented and albino rats by electroretinography and visual evoked potentials

Purpose  To check differences in visual function between Wistar (albino) and Long-Evans (pigmented) rats. Methods  The animals were born in our facilities and reared under identical light conditions avoiding bright light. Visual electrophysiology was performed at the ages of 1.5, 4, 7 and 10 months (electroretinography, ERG) and at 1.5 and 7 months (visual evoked potentials, VEP). Results  ERG measurements showed that: 1) The amplitudes of both scotopic and photopic b-waves were markedly larger in Long-Evans rats than in Wistar rats, and also the amplitudes of scotopic oscillatory potentials and photopic 30 Hz Flicker amplitudes, 2) scotopic a-wave amplitudes were larger in Wistar rats at low light intensities, whereas they were smaller in bright light, 3) both a-wave and b-wave latencies were shorter in Wistar rats, 4) the maximum response Rm_P3 was larger in Long-Evans rats, 5) the sensitivity parameter S was larger in Wistar rats, and 6) the post-receptoral response of cones was smaller in Wistar rats. In the VEP measurements, amplitudes of both photopic and scotopic visual evoked potentials of Long-Evans rats were only slightly larger than those of Wistar rats. Conclusions  ERG b-wave amplitudes are markedly decreased in Wistar rats, which requires further investigation. As the b/a and OP/a ratios were also decreased in Wistar rats, it can be suggested that post-receptoral processing, in particular, is impaired in albino animals. Presented in part at the 105th congress of the DOG, 20–23 September 2007 in Berlin. The authors have full control of all primary data and agree to allow Graefe’s Archive for Clinical and Experimental Ophthalmology to review their data upon request.     

Alteration in pattern reversal visual evoked potential in pediatric population with amblyopia and spherical refractive errors

Purpose:To study the effect of refractive errors on pattern visual evoked potential (VEP) recordings in the pediatric population.Methods:This cross-sectional observational study assessed 240 eyes of 120 participants attending the outpatient department of a tertiary care center in North India. Participants were between 8 and 18 years of age; 30 participants each were recruited into four groups, namely emmetropia, myopia, hypermetropia, and amblyopia. They were then subjected to pattern reversal VEP, with P-100 amplitude and latency recorded for each participant.Results:The emmetropic group in this study provided normal values of P-100 parameters, namely P-100 latency and P-100 amplitude with readings of 115.78 ± 10.19 ms and 11.11 ± 4.08 mV, respectively. P-100 amplitude was significant compared to P-100 latency in detecting the presence or absence of a specific type of refractive error. It was found that there was a significant association between severity of myopia and P-100 latency (both unaided and aided) with P < 0.05. The severity of hypermetropia showed a significant association with P-100 amplitude (unaided) (P < 0.05). Receiver operating characteristics analysis revealed P-100 amplitude to be a good predictor of refractive error and the cut-offs were calculated.Conclusion:The P-100 parameters of the pediatric Indian population were comparatively higher than conventional values. P-100 latency seemed to better correlate with myopia, while hypermetropia correlated with P-100 amplitude. P-100 amplitude appears to be the most significant predictor of the presence of refractive error in an individual.     

Correlation of pattern reversal visual evoked potential parameters with the pattern standard deviation in primary open angle glaucoma

AIM:To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation (PSD) of Humphrey visual field could be associated with visual evoked potential (VEP) parameters of patients having primary open angle glaucoma (POAG).METHODS:Visual field by Humphrey perimetry and simultaneous recordings of pattern reversal visual evoked potential (PRVEP) were assessed in 100 patients with POAG. The stimulus configuration for VEP recordings consisted of the transient pattern reversal method in which a black and white checker board pattern was generated (full field) and displayed on VEP monitor (colour 14”) by an electronic pattern regenerator inbuilt in an evoked potential recorder (RMS EMG EP MARK II).RESULTS:The results of our study indicate that there is a highly significant (P<0.001) negative correlation of P100 amplitude and a statistically significant (P<0.05) positive correlation of N70 latency, P100 latency and N155 latency with the PSD of Humphrey visual field in the subjects of POAG in various age groups as evaluated by Student’s t-test.CONCLUSION:Prolongation of VEP latencies were mirrored by a corresponding increase of PSD values. Conversely, as PSD increases the magnitude of VEP excursions were found to be diminished.     

刺激条件对扫描图像翻转诱发电位视力的影响

目的研究时间频率和空间频率对扫描图像翻转诱发电位视力准确度的影响。方法比较10例20眼正常志愿者SPVER视力和对数视力表视力。在SPVER视力的测定中用7个不同空间频率的光栅条纹连续扫描。所得的数据经离散傅立叶分析后，获得振幅-空间频率曲线，并通过外推法估计其视力。诱发电位测定的时间频率分别为8、12、16、20、24Hz，根据测试距离来调整空间频率。结果与视力表视力比较各时间频率测定的SPVER视力有良好的相关r=0．87～0．5，各空间频率间测定的视力有良好的相关性r=0．72～0．96。三种不同空间频率测试的SPVER视力和视力表视力比较在低视力段无差异在高视力段所设空间频率越高结果越接近视力表视力。结论SPVEP视力与视力表视力有良好的相关性。但为使测定的结果更准确可根据条件选取相应的时间和空间频率。