屈光参差性弱视同步记录多焦视觉诱发电位和多焦视网膜电图的对比研究

目的探讨弱视发病的可能机制。方法采用VERIS Science^TM4．2多焦电生理系统对24例屈光参差性弱视患者双眼分别进行多焦图形视觉诱发电位(VEP)、视网膜电图(ERG)同步记录和多焦闪光VEP、ERG同步记录,并与30例正常对照的结果进行比较。结果在不同视网膜区域弱视眼多焦图形VEP、ERG反应和多焦闪光VEP、ERG二阶反应振幅均降低,VEP特征峰潜时延长,ERG潜时无改变。弱视眼多焦闪光一阶反应VEP、ERG的反应振幅密度均降低,潜时无明显改变。多焦图形VEP波形异常程度中心区大于周边区,且与弱视眼的视力异常程度有相关性。弱视眼多焦图形和闪光二阶反应的视网膜．皮层传导时间(RCT)显著延长,闪光一阶反应RCT三组无明显差异。结论弱视眼的mVEP和mERG具有明显的特征性改变,表明弱视眼的视网膜、视觉传导通路和视皮层都存在明显损害,且中心区损害重于周边区,中枢损害重于视网膜。(中华眼科杂志,2005,41：41-46)     

斜视性弱视多焦视觉诱发电位的研究

目的 研究斜视性弱视患者多焦视觉诱发电位(mfVEP)的特征性变化,探讨弱视的发病机制,对弱视预后的判断给予临床指导.方法 收集斜视性(内斜)弱视患者30例、正常人30例,分为斜视性弱视组、对侧眼组和正常对照组3组,采用多焦电生理系统进行图形mfVEP检测,分析潜伏期与振幅密度.结果 6个离心度上弱视组反应振幅密度较对侧组和正常组均显著降低.弱视组及对侧组的鼻侧视网膜反应振幅密度均低于颞侧视网膜,潜伏期延长.斜视性弱视患者斜视度与弱视眼视力及mfVEP波形异常程度之间均无明显相关性.结论 斜视性弱视患者mfVEP表明弱视患者的视皮层与视觉传导通路均存在损害,mfVEP检查可为弱视的诊断、治疗及预后判断提供客观依据.     

斜视性弱视眼的多焦视诱发电位特征

目的研究斜视性弱视眼视野各部位视功能的变化.方法记录和分析了5例斜视性弱视眼和45例正常对照眼的多焦VEP.刺激图形由61个六边形单元组成,每个刺激单元内有黑白格子,刺激野直径约13.6°.在VERIS系统电脑程序(伪随机双极m序列)控制下,各刺激单元同时并互相独立地进行黑白翻转刺激,通过用快速Walsh变换计算刺激与反应的互相关函数,分离提取到各自的反应波形.结果斜视性(内斜)弱视眼在中央视野和颞侧视野,多焦VEP潜伏期延长、振幅下降.按不同离心度的环分组统计,斜视性弱视眼与正常对照眼比较,P1波潜伏期平均值在中央凹和第一环分别延长20.2ms和11.2ms;P1-N2振幅平均值在中央凹下降68.8%,在第一环下降52.6%,在第二环下降47.5%,N1-P1振幅平均值在中央凹下降54.4%.按鼻颞侧分组统计,斜视性弱视眼与正常对照眼比较,潜伏期平均值在颞侧视野延长10.6ms;P1-N2振幅平均值在颞侧下降66.5%,N1-P1振幅平均值在颞侧下降63.7%.斜视性弱视眼潜伏期平均值在颞侧视野比在鼻侧视野延长11.2ms;P1-N2振幅平均值在颞侧视野比在鼻侧视野下降64.2%,N1-P1振幅平均值在颞侧视野比在鼻侧视野下降64.2%.结论本研究证实,斜视性(内斜)弱视眼在中央视野和颞侧视野,视功能下降较显著.     

斜视性弱视儿童多焦视觉诱发电位的研究

目的:研究斜视性弱视多焦视觉诱发电位特征,探讨弱视发病机制。方法:采用德国Roland公司的RETIscan3.15多焦视觉电生理仪,记录和分析了斜视性弱视儿童80眼,外斜43眼内斜37眼,并与正常对照组儿童60眼作比较。结果:弱视眼N1-P1波振幅密度平均值和P1-N2波振幅平均值较正常组儿童在中央视野有下降,随离心度增加,这种现象呈下降趋势。P1波潜伏期平均值无明显异常。正常组和各斜视性弱视组N1-P1波振幅密度平均值:颞侧<鼻侧,P1波潜伏期平均值:颞侧>鼻侧。结论:斜视性弱视mfVEP中心区损害重于周边区,波形异常程度与弱视程度无关。内斜性弱视波形异常程度大于外斜性弱视。     

用同步记录法对斜视性弱视儿童弱视眼P—ERG和P—VEP的研究

目的应用临床电生理手段对斜视性弱视的中枢及外周损害作一些探讨。方法使用丹麦Ｅｖｏｍａｔｉｃ４０００型电生理仪,全视野翻转棋盘格作刺激,选择９０’、４６．６’、２０．７’三种空间频率,Ｐ－ＥＲＧ与Ｐ－ＶＥＰ同步记录的方法,对２３例单眼斜视性弱视儿童进行电生理检测,弱视眼Ｐ—ＥＲＧ记录使用双眼注视、注视标调整寻找ｂ波最大振幅的方法,并与正常对照组儿童进行比较。结果弱视眼Ｐ－ＶＥＰＮ７５潜伏期、Ｐ１００潜伏期较正常儿童组延长,Ｐ１００振幅较正常儿童组降低。弱视眼Ｐ－ＥＲＧ与正常儿童组比较并无明显异常。结论斜视性弱视的损害、神经传导的时间延迟主要发生在视觉通路视网膜以上的部位,视网膜并无明显受损。     

弱视患者多焦视网膜电图的研究

目的　探讨弱视患者多焦视网膜电图 (mfERG)的改变和视网膜的损害。方法　对 2 8例屈光参差性弱视患者 (A组 )、2 5例斜视性弱视患者 (B组 )、14例屈光不正性弱视患者 (C组 )行mfERG检测 ,记录总体和不同视野区域的一阶、二阶反应N1波、P1波的振幅密度和潜时 ,并与正常对照者 (D组 )进行比较。结果　A、B、C组mfERG的一阶反应P1波、N1波和二阶反应P1波的振幅密度均降低 (P <0 0 5 ) ,且这种改变在视野中央明显 ,随偏心度的增加而减少。 4组mfERG均表现颞侧视野一阶反应P1波、N1波振幅密度较鼻侧视野降低 ,且潜时延长 (P <0 0 5 ) ;上方视野二阶反应P1波振幅密度均低于下方视野 (P <0 0 5 ) ,其余指标上、下方视野差异无显著意义 (P >0 .0 5 )。A、B、C组各阶反应波的潜时与D组比较 ,差异均无显著意义 (P >0 0 5 )。弱视患者视力与mfERG指标之间无线性相关关系 (P >0 0 5 )。A、B组中健眼mfERG指标与患眼比较 ,差异均有显著意义 (P <0 0 5 ) ;与D组比较 ,差异无显著意义 (P >0 0 5 )。结论　弱视患者mfERG有明显改变 ,提示弱视眼视网膜神经节细胞受损 ,但神经信息的传递无延长。     

斜视性弱视儿童不同注视性质多焦视觉诱发电位的研究

目的对比研究斜视性弱视不同注视性质患者多焦视觉诱发电位特征性变化,探讨弱视发病机制。方法采用德国Roland公司的RETIscan3.15多焦视觉电生理仪,提取FOK(一阶反应)。共记录和分析了不同注视性质斜视性弱视儿童52眼(中心凹型26眼;黄斑型21眼;黄斑周围型5眼),并与正常注视性质对照组儿童(60眼)作比较。结果斜视性弱视眼:中心凹注视眼图形中央区振幅下降陡峭,潜伏期最长。随离心度加大,周边区振幅下降平缓;黄斑注视眼中央区振幅下降平缓,潜伏期减小。随离心度加大,周边区振幅逐步下降;黄斑周围注视眼图形杂乱,中心至周边一侧可见多个小的异常波峰隆起,呈不对称分布。黄斑型注视组与黄斑周围型注视组在不同离心度mfVEP反应无统计学差异。结论虽然旁中心注视眼mfVEP不能反映视网膜中心区真实机能,但是异常网膜对应区域受到的抑制还是重于周边区域。     

斜视性弱视与屈光参差性弱视对比敏感度函数的研究

目的研究斜视性弱视及屈光参差性弱视患者弱视眼的对比敏感度函数。方法用稳态ＶＥＰ的方法对３２例斜视性弱视、１９例屈光参差性弱视及正常儿童的对比敏感度进行测定。结果两种弱视患者弱视眼的ＣＳＦ均较正常儿童的ＣＳＦ低平，表现为中、高空间频率区ＣＳＦ明显受损，而两种弱视间的ＣＳＦ未见显著性差异。结论两种弱视可能均为Ｘ通道受损所致。     

眼挫伤VEP、ERG联合检查的意义

目的 探讨VEP、ERG在眼挫伤中应用的意义。方法 对我院近3年来无屈光间质障碍的眼挫伤患者68例68眼，除行常规视力、裂隙灯和眼底检查外，予行VEP、ERG检查。结果对伤后视力下降，矫正不佳，常规检查又未能查出明显异常者，VEP或ERG均有异常。结论 VEP、ERG联合应用是眼挫伤后早期诊断及视功能评价的客观检测手段。     

VEP、F—ERG在眼挫伤中应用研究

目的 视觉诱发电位（VEP）和闪光视网膜电图（F-ERG）联合应用评价钝挫伤眼的视功能。方法 86例（86眼）钝挫伤眼及健康对侧眼为对照组,按照国际标准分别行VEP和F-ERG检查。比较分析两组间VEP P100波潜时值、F-ERG的a、b波幅值的平均值。结果 眼挫伤组VEP P100波潜时明显延迟,波幅值明显降低;F-ERG a、b波幅明显降低,其异常率随视功能损伤程度的加重而增加。结论 VEP和F-ERG联合应用是评价眼挫伤视功能及早期确定诊断的客观检测手段。     

儿童弱视治疗前后VEP、ERG检查的临床意义的探讨

目的探讨儿童弱视治疗前后VEP、ERG检查的临床意义。方法对64例弱视儿童共100只弱视眼进行治疗前、后VEP，ERG的改变进行观察。结果弱视儿童治疗前、后VEP P100波潜伏期、振幅、A／L值均有显著改变（P〈0．05），ERGb波潜伏期亦有显著改变（P〈0．05）。结论提示视觉电生理检查作为客观的视觉功能检查法，对弱视儿童治疗前后的疗效评价有较高的评估价值。     

屈光参差性弱视mfVEP的临床分析

目的分析屈光参差性弱视患者多焦视觉诱发电位(mfVEP)的特征性变化,以探讨弱视发病的可能机制。方法采用VERISScienceTM4.2多焦电生理系统对23例屈光参差性弱视患者、30例正常人进行双眼图形mfVEP检查,以潜伏期与振幅为分析指标,进行了屈光参差性弱视眼、对侧眼和正常对照三组mfVEP的对比研究。结果在六个离心度上弱视眼反应振幅密度较其对侧眼和正常眼均显著降低,潜伏期延长。弱视眼波形异常程度随离心度增加而减小,在六个离心度上弱视眼mfVEP的波形异常程度都与弱视眼的视力异常程度有相关性。结论屈光参差性弱视患者的mfVEP具有明显的特征性改变,表明弱视患者的视觉传导通路存在明显损害,在中心区损害重于周边区,弱视眼波形异常程度与视力异常程度有明显的相关性,mfVEP检查对于弱视的诊断、治疗和预后判断具有一定的指导意义。     

斜视性弱视皮层损害的功能性磁共振成像研究

目的 利用血氧水平依赖的功能性磁共振成像(BOLD—fMRI)技术，探讨斜视性弱视的可能机制。 方法 以1.5T磁共振成像系统采集11例斜视性弱视、8例正常人枕叶视皮层BOLD-fMRI数据，比较斜视性弱视组与正常组皮层双眼像素指数以及斜视性弱视组两眼皮层神经元的平均活动水平。结果 正常组双眼像素指数：47．82％±5．34％，斜视性弱视组：14．13％±4．55％，两组差异有显著性的意义(P<0．05)。选用高空问频率(1、2 cycle／degree)刺激时，弱视眼驱使皮层神经元平均活动水平较对侧眼降低(PO．05)。 结论 斜视性弱视可能与皮层双眼细胞减少以及弱视眼对高空间频率视信息存在采样、编码的异常有关。BOLD-fMRI为深入探讨弱视的神经病理机制提供了新的途径。 （中华眼底病杂志，2004，20：19-22）     

The influence of luminance on the multifocal ERG

Purpose To assess the efficacy of high luminance in increasing the amplitude of the multifocal electroretinogram (mfERG). We examined 5 male and 5 female volunteers in the age of 22–52 years (median 28 years). Three different stimulus luminance levels were applied: the bright areas of the stimulus pattern were set to 150, 300 and 500 cd/m². We recorded the potentials via DTL electrodes using the VERIS Science 4.4 system with 61 hexagons, pupils were dilated. Analysis was based on the 5 ring averages.Results Across all hexagons and subjects, the response density (∼amplitude) rose by 20% when increasing the luminance by a factor of 3.3. The peak times decreased slightly with higher luminance, by less then 1.5 ms.Conclusions Combining the present results with those from two previous studies, the gain (= relative amplitude increase for relative luminance increase) is close to 0.4 over a range of 56–700 cd/m². The stimulus luminance range suggested in the mfERG guidelines seems well chosen.     

Recording of Both VEP and Multifocal ERG for Evaluation of Unexplained Visual Loss

The purpose of this retrospective study was to determine the relevance of both visual-evoked potentials (VEP) and multifocal electroretinography (mfERG) to evaluate unexplained visual loss. Seventy-two consecutive patients (1996–2002) with visual disturbances of unknown origin underwent both VEP and mfERG (ISCEV standard). The mean age was 42.4 years (11.8–74.5) and median visual acuity 0.5 (no light perception – 1.0). Symptoms reported included visual acuity loss (n=69), visual field defects (n=11), disturbances of colour vision, light or dark adaptation (n=10). VEP and mfERG were normal in 43% (n=31). Both VEP and mfERG were pathological in 24% (n=17). In a further 18% (n=13) only the mfERG was pathological and in 15% (n=11) only the VEP was pathological. Macular dysfunction as detected with mfERG was present in 73% of 41 patients with at least one pathological test. Neuroimaging (MRI, CCT) and/or neurological examination was performed in 27/72 patients (38%), to account for unexplained visual loss, prior to the electrophysiological tests; these were normal in all patients. Electrophysiological tests revealed disturbances of the post-retinal visual pathway in only 3/27 patients. In 12/27 patients, mfERG revealed a macular disorder; in a further 12/27 patients VEP and mfERG were normal. The combined evaluation of VEP and mfERG is useful both to establish the area of dysfunction and the normality of the visual system. Electrophysiological testing prior to neuroimaging is recommended for patients where clear clinical signs of cerebral disorders are not evident. This reduces the frequency of unnecessary neuroimaging and associated radiation exposure.     

Plaid perception is only subtly impaired in strabismic amblyopia

Amblyopes exhibit a global motion anomaly that implicates processing beyond the local motion analysis of V1 possibly involving areas MT and MST in the extra-striate cortex. Here, we sought to further investigate this deficit by measuring the perception of moving plaid stimuli by amblyopic observers, since there is good physiological evidence that the motion of such stimuli is determined by processes beyond V1. The conditions under which the two moving components constituting the plaids were seen to cohere or move transparently over one another were investigated by manipulating their relative spatial frequencies. Percepts were measured using both short presentation durations, where both the percept and the direction of motion were reported, and long presentation durations where the bi-stability of the stimulus was directly measured. In addition, we measured the ability of amblyopic eyes to perceive globally coherent motion in a multiple aperture stimulus. We found a small increased tendency for both amblyopic and fellow-fixing eyes to perceive short duration plaid stimuli as coherent relative to control eyes, but no difference for long duration plaids. In addition, amblyopic eyes saw less coherence in multiple aperture stimuli than fellow-fixing eyes but were not reliably different from control eyes. We therefore conclude that the neural mechanisms underlying plaid perception are only subtly abnormal in amblyopia.     

Impaired spatial and binocular summation for motion direction discrimination in strabismic amblyopia

Amblyopia is characterised by visual deficits in both spatial vision and motion perception. While the spatial deficits are thought to result from deficient processing at both low and higher level stages of visual processing, the deficits in motion perception appear to result primarily from deficits involving higher level processing. Specifically, it has been argued that the motion deficit in amblyopia occurs when local motion information is pooled spatially and that this process is abnormally susceptible to the presence of noise elements in the stimulus. Here we investigated motion direction discrimination for abruptly presented two-frame Gabor stimuli in a group of five strabismic amblyopes and five control observers. Motion direction discrimination for this stimulus is inherently noisy and relies on the signal/noise processing of motion detectors. We varied viewing condition (monocular vs. binocular), stimulus size (5.3-18.5°) and stimulus contrast (high vs. low) in order to assess the effects of binocular summation, spatial summation and contrast on task performance. No differences were found for the high contrast stimuli; however the low contrast stimuli revealed differences between the control and amblyopic groups and between fellow fixing and amblyopic eyes. Control participants exhibited pronounced binocular summation for this task (on average a factor of 3.7), whereas amblyopes showed no such effect. In addition, the spatial summation that occurred for control eyes and the fellow eye of amblyopes was significantly attenuated for the amblyopic eyes relative to fellow eyes. Our results support the hypothesis that pooling of local motion information from amblyopic eyes is abnormal and highly sensitive to noise.     

Amplitude calculation in multifocal ERG: comparison of repeatability in 30 Hz flicker and first order kernel stimulation

BACKGROUND: In multifocal flicker stimulation, each step of the M-sequence consists of four consecutive flashes with a frequency of 30 Hz. The resulting amplitudes can be calculated by means of a discrete fourier transformation (DFT). With this method, amplitudes can be calculated without having to localise peaks and troughs and set cursors. The purpose of this study is to compare the re-test stability of this method to conventional mfERG stimulation. METHODS: We examined 27 healthy subjects using a RETI-scan device (Roland Consult, Wiesbaden). We used 61 hexagons within a 30 deg. visual field. We compared the classic first order kernel (FOK) stimulation with the multifocal 30 Hz Flicker (mfFlicker-ERG) stimulation. Repeatability was calculated using coefficients of variation. RESULTS: Both methods had coefficients of 15% for the sum P1-amplitude and the DFT results, respectively. The amplitudes calculated by flicker and DFT were approximately 25% smaller than the FOK amplitudes. CONCLUSIONS: This study showed no difference of re-test repeatability between the mfFlicker-ERG and the conventional first order kernel method. Since the mfFlicker-ERG method does not require a definition of peaks and troughs in order to calculate the amplitudes, we believe that a common source of error is eradicated, especially when dealing with distorted or atypical curves.