视觉诱发电位在颌面外伤致视神经挫伤诊断及预后中的应用

目的:应用视觉诱发电位检查颌面外伤致视神经挫伤程度,确定视功能损伤程度及预后估计。方法:对颌面外伤引起的单侧挫伤眼65例65眼进行治疗前、治疗后视觉诱发电位(visual evoked potontial,VEP)检查,以自体的健眼作为对照。结果:损伤眼视力及VEP的P100潜伏期及波幅异常,视力损害越重,VEP改变越明显,且预后越差。结论:VEP是视神经挫伤早期诊断,判断预后的客观检查方法。     

机械性眼损伤后视力的客观评估

目的：将诱发电位技术应用于眼伤后视力的客观评定。方法：全部受检对象均为志愿合作,他们的视力范围能覆盖整个国际标准视力表。以最小信号视角条件下P100波幅和潜伏期作为检测指标,进行视力表视力相同的各种类型外伤眼的比较研究及统计分析,联合应用闪光VEP及模式翻转VEP对全部受检眼视力进行评估。结果：选定P㈨波幅作为视力量化评价指标,联合应用闪光VEP及最小信号视角条件下P100波幅与视力问的回归方程对60眼视力的客观评估结果与国际标准视力表筛查结果比较无显性差异。结论：联合应用闪光VEP及最小信号视角条件下P100波幅与视力间的回归方程对受检视力的评估切实可行、简便且能达到量化分析的目的。     

视觉诱发电位对挫伤眼视神经损伤的评价

目的：探讨眼挫伤后视觉诱发电位（VEP）变化特征。方法：对71例（115眼）眼挫伤行VEP检查。视力≥0．1者行图形视觉诱发电位（P－VEP）检查（100眼，A组）；视力＜0．1者行闪光视觉诱发电位（F－VEP）检查（15眼，B组）。A组根据挫伤后视力情况又分为3个亚组。结果：A组所有伤眼P100波幅较正常值明显降低（P＜0．01），而蜂潜时夫明显改变（P＞0．05）；3个亚组间P100波幅值有明显差异（P＜0．01）。B组15眼P100与对侧健眼比较，峰潜时明显延长，波幅明显降低（P＜0．01）。结论：视觉诱发电位对眼挫伤后视神经损伤的诊断具有客观性和敏感性，有定量诊断价值。     

眼挫伤30例视力的恢复与视觉诱发电位变化相关性的分析

目的探讨将诱发电位技术应用于眼外伤后视力评估的可行性。方法眼挫伤致视力受损者30例（48眼）进行视觉诱发电位检查,每例受检对象均记录3次,检测时间分别为伤后1月、3月及1年,以刺激模式空间频率、P100波幅和潜伏期作为检测指标,检测与记载各受检眼P100波幅和潜伏期的变化,以盲测的视力表视力为参照,分析不同时期视觉诱发电位结果与视力恢复状况的相关性。结果一定的视觉刺激模式空间频率大小与视力表现出一致性,P100波幅与视力水平呈正相关,P100波潜伏期长短与视力状况未见必然联系,视觉诱发电位变化与眼挫伤后视力的恢复状况有关,视力表筛查与VEP检测结果比较无差异。结论应用视觉诱发电位技术可对眼挫伤后视力的恢复状况进行客观评估。     

弱视儿童扫描视觉诱发电位视力与国际标准视力的比较

目的 探讨扫描翻转图形视觉诱发电位(SPVEP)在弱视儿童客观视力评估的可行性.设计前瞻性病例研究.研究对象 80例(148眼)弱视儿童及26例(52眼)正常视力儿童.方法 弱视儿童进行扫描图形翻转视觉诱发电位视力(SPVEP-A)与国际标准E字视力检测;正常视力儿童进行SPVEP-A、传统瞬态图形视觉诱发电位(PVEP)视力(PVEP-A)与E字视力检测,对检测结果进行相关性分析.使用LKC公司UTES.E3000型视觉电生理仪检测SPVEP,选用0.2～18.8cpd的25个空间频率正弦光栅连续刺激视网膜,经离散傅立叶分析,获得振幅.空间频率曲线,并将相关直线外推至0振幅,获得SPVEP视力.在PVEP检测中将典型VEP波形的最高空间频率作为PVEP视力.主要指标SPVEP.A、PVEP-A和E字视力.结果 弱视患者矫正视力在0.1～0.8之间,SPVEP-A在0.35～0.9之间,SPVEP-A与E字视力的相关系数r=0.602(P＜0.01). SPVEP-A两次重复检测的相关系数r=0.448.轻度弱视SPVEP-A与E字视力的相关性(r=0.773)优于中重度弱视者(r=0.590).正常儿童SPVEP-A与E字视力的相关系数r=0.424,PVEP-A与E字视力的相关系数r=0.679.SPVEP-A与E字视力比较存在高估、低估现象,在E字视力的低视力段,SPVEP-A存在高估现象;在E字视力的高视力段,SPVEP-A存在低估现象.结论 扫描翻转图形视觉诱发电位是筛查弱视儿童客观视力的一种方法.SPVEP-A与E字视力存在明显的止相关,但变异较大,应进一步提高检测的稳定性与准确性.(眼科,2008,17:269-273)     

儿童单眼视力缺陷的图形视觉诱发电位分析

目的：研究图形视觉诱发电位（P－VEP）判断儿童单眼视功能的三种方法（波幅差异比率法、波幅比率法、潜伏斯差异法）的敏感度和特异度，以寻找一种可靠、 有效的发现儿童单眼视力缺陷的VEP视力评估手段。方法：用P－VEP检查了178名正常儿童，建立每一种方法的正常值范围。用P－VEP测定两组具有单眼疾患的儿童（一组患眼视力正常，另一组患眼视力异常）。评估每种方法的敏感度和特异度。结果：三种方法在各年龄组均具有较高的特异度（0．83－0．94）。波幅差异比率法的敏感度在各年龄组均明显高于波幅比率法和潜伏期差异法。结论：VEP波幅差异比率法估计视力，在各年龄组均具有较高的敏感度和特异度，因而是发现单眼视力缺陷的较好的分析指标。     

烟毒性弱视的图形视觉诱发电位探讨

目的　研究烟毒性弱视的图形视觉诱发电位的变化。方法　检验对象为 36例 72眼烟毒性弱视患者 ,视力数指～ 0 .8,眼科常规检查无明显病变。检测条件 :视刺激为黑白棋盘格 ,空间频率 1°2 2′视角 ,时间频率 2 .9Hz ,对比度10 0 % .结果　 72眼中 32眼P VEP无波 ,4 0眼P10 0潜伏期延迟。结论　研究说明图形视觉诱发电位是诊断烟毒性弱视特别是早期眼底正常的一种好方法。     

稳态闪光视诱发电位的临床应用

本文应用30Hz 闪光刺激,记录稳态闪光视诱发电位(Steady-state flash visual evoked poten-tials,FVEP),经离散富里叶转换(discrete Fourier transform,DFT),提取基波和二次谐波的幅值和相位作为记录波的特征值.应用此法,对46例(89只眼)正常人和78例(109只眼)眼病患者进行测定分析.结果表明,正常对照组的特征值在各年龄组间有显著性差异.病人组中,视神经疾病(35只眼),老年黄斑变性(25只眼)和已累及黄斑部的视网膜脱离组(9只眼)的异常视功能检出率分别为82.9%、92%和100%.28只白内障眼和12只玻璃体混浊眼,初步观察,术前稳态FVEP 正常或轻度降低者,术后视力可达0.4以上.本研究的主要意义在于评价图形 VEP 不能完成的患者的视功能。并集中反映与黄斑区视锥细胞相连的传入神经的电活动,计算机操作方便,能获取更有用的信息.眼科学报 1993;9:70-74。     

应用视觉诱发电位分析视力的价值

目的:研究如何将诱发电位技术应用于视力的客观评定.方法:视力范围0.1～1.5志愿合作受试者共180眼,运用模式翻转视觉诱发电位(PRVEP)技术检测与记载各受检眼各不同信号视角条件下的结果,探究可靠的检测指标.应用SPSS软件对收集数据作统计学处理和分析.结果:确定最小信号视角是客观评估视力的基础,选定P100波幅作为视力量化评价指标.通过对一定条件下P100波幅与视力表视力进行简单相关回归分析,显示二者呈正相关.结论:最小信号视角、P100波幅可作为确切的检测指标.     

思利巴治疗儿童弱视的初步临床观察

目的　探讨左旋多巴治疗儿童弱视的效果。方法　 1 2 8例 2 4 0眼 5～ 1 2岁弱视儿童 ,随机分成 2组 ,治疗组口服左旋多巴片 ,对照组口服药用淀粉片。治疗 3个月 ,随访 3个月。对视力 ,图形视觉诱发电位 (P VEP)等结果进行分析。结果　治疗组在治疗后视力提高。P VEP中P10 0 波潜伏期缩短 ,振幅提高。结论　左旋多巴治疗儿童弱视有一定效果     

闪烁光ERG和闪烁光VEP对玻璃体混浊患者的视功能评价

对34例玻璃烽混浊患者术前30Hz闪烁光ERG、10HZ闪烁光VEP和30Hz闪烁光VEP的结果，使用离散博里叶分析法，提取波形特征值振幅和相位，与术后视力进行比较．多元回归分析表明：ERG与VEP的振幅都与术后视力呈正相关，复合相关系数r=0.718(P＝0.0076)；相位则无相关。联合应用ERG和VEP检测时术后视力有较好的预测作用。 （中华眼底病杂志，1995，11：159-161）     

Spatial frequency sweep VEP: visual acuity during the first year of life

The grating acuity of 197 infants from 1 week to 53 weeks of age was measured using the visual evoked potential (VEP) in response to counterphase grating stimulation. The gratings were presented as a 10 sec spatial frequency sweep which spanned the acuity limit. The amplitude and phase of the second harmonic response were extracted by discrete Fourier analysis. The VEP amplitude versus spatial frequency function showed narrow spatial frequency tuning with amplitude peaks at one or more spatial frequencies. The phase of the response at medium to high spatial frequencies was generally constant at a spatial frequency peak, followed by a progressive phase lag with increasing spatial frequency. Grating acuity was estimated by linear extrapolation to zero microvolts of the highest spatial frequency peak in the VEP amplitude versus spatial frequency function. This visual acuity estimate increased from a mean of 4.5 c/deg during the first month to about 20 c/deg at 8-13 months of age. The VEP acuities at 1 month are a factor of three to five higher than previously reported for pattern reversal or pattern appearance stimuli. By 8 months VEP grating resolution was not reliably different from adult levels in the same apparatus.     

扫描视觉诱发电位（SVEP）对成年野生型C57BL/6J小鼠客观视力评估的可靠性

目的　评价扫描视觉诱发电位（sweep visual evoked potential,SVEP）对成年野生型C57BL/6J小鼠客观视力评估的可靠性。方法　选取6只鼠龄32~33 d的正常野生型C57BL/6J小鼠,雌雄不限,麻醉小鼠将记录电极 （2 mm直径的钨电极） 放置在λ缝旁3 mm的左皮质（受刺激右眼的对侧）,深度为皮层下400 μm,额部的针状电极作为参考电极,尾部的针状电极作为接地电极,记录过程中遮盖左眼（未受刺激眼）,屏幕放置在小鼠眼前20 cm处,视野范围为100°（水平）×82°（垂直）,平均亮度为25 cd·m^-2;采用垂直方向的正弦波光栅刺激,刺激对比度为100%,包括11个空间频率,时间频率为1 Hz;整个扫描过程需要12 s（11 s空间频率+ 1 s预适应）,数据的误差值稳定后取其平均值。分别记录左右眼对应的视皮层VEP波形。不同刺激频率给予20次刺激,每眼重复测量3~4次,取其平均值,左右眼交替试验。以空间频率对数作为x轴,经离散傅里叶分析所得反应振幅为y轴建立坐标系,选取临近噪点的4个有效测定点行线性回归,回归曲线外推法至振幅为0处的空间频率即为推断的客观视力。结果　空间频率为0.05 c·deg^-1时,SVEP提示N100波振幅达到峰值。随着逐步增加刺激空间频率,SVEP振幅降低﹑潜伏期延迟,空间频率为0.65 c·deg^-1时视皮层电反应几乎无法与噪点区分;6只小鼠右眼空间频率视力为（0.56±0.04）c·deg^-1,左眼为（0.50±0.04）c·deg^-1,两眼空间频率视力比较差异无统计学意义（P>0.05）;12眼空间频率视力为（0.53±0.03）c·deg^-1。结论　可以使用SVEP评估小鼠客观视力,此方法与行为方法测得的视力相近,但SVEP评估小鼠视力结果更为客观精确,所需时间更短。     

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。     

Comparative study of electrophysiological and psychophysical measurement of the contrast sensitivity function in humans

We measured the human contrast sensitivity function (CSF) both electrophysiologically with the steady-state visual evoked potential (VEP) and psychophysically using a method of ascending limits. VEP contrast thresholds were determined using a rapid recording technique in which the contrast of a counterphase modulated sine wave grating was swept logarithmically from 0.5 to 40% over a period of 10 s. For this pattern reversal stimulus the amplitude and phase of the second harmonic response as a function of contrast were measured using a discrete Fourier transform (DFT). Psychophysical thresholds were determined on the same trials used to record the VEP. Near threshold the VEP amplitude vs. contrast function was approximately linear and VEP contrast thresholds were estimated by a linear extrapolation to zero amplitude. The contrast thresholds obtained by the two methods correlated at 0.914 for 5 observers, with a mean discrepancy of only 12%. At higher contrasts, the VEP amplitude vs. contrast function often became nonmonotonic, sometimes showing two amplitude peaks.     

First-order Wiener kernel visually evoked potentials obtained from multiple sclerosis patients

Visually evoked potentials (VEP) were measured in multiple sclerosis patients with five sizes of reversing check stimuli. The VEPs were obtained using random binary sequence triggered check reversals. The random binary sequence was cross-correlated with scalp potential responses to obtain the estimates of the linear response of the system.For each evaluation a series of five VEPs, one for each of five check sizes, was done. A correlation coefficient was calculated to evaluate check size versus amplitude of the major negative wave. A tabulation was made to compare Snellen chart visual acuity with these correlation coefficients. For the eyes with a Snellen acuity of 20/20, 63% of the VEP amplitudes increased as the check size was decreased with correlation coefficients of -0.6 to -1. For the eyes with a Snellen acuity of 20/70 or less the amplitude decreased with the check size decrease, showing a correlation coefficient of +0.6 to +1 in 45% of the evaluations. The check size giving the largest amplitude was also tabulated with respect to the visual acuity, but did not appear to have as strong a relationship to visual acuity.     

Fourier-analysed Steady-state VEPs in Pre-school Children with and without Normal Binocularity

Pre-school children aged 4–5 were examined with steady-state VEP in response to a sinusoidal grating pattern with a spatial frequency of 4 c/deg, reversing at rates 5, 10, and 15 Hz. Normal children (n = 10) were compared with subjects lacking stereo perception (n = 6) and with subjects showing significant unilateral amblyopia with visual acuity in the worse eye <0.5 (n = 7). Fast Fourier Transform was used for analysis of the crude steady-state VEP responses. Compared to normals, the subjects lacking stereo perception showed a significantly lower power of the second harmonic in the response evoked by binocular stimulation with gratings reversed at 15 Hz. The amblyopic group showed a significant difference between the dominant and the non-dominant eye regarding the first harmonic power in the responses evoked by gratings reversed at 5 and 10 Hz. These findings are discussed in relation to the magnocellular and parvocellular visual pathways and suggested models for linear and non-linear processing of visual signals.     

The effects of contrast and length of gratings on the visual evoked potential

Visual evoked potentials (VEP's) were obtained to grating stimuli modulated in phase at 8 Hz. The amplitude of the VEP was linearly related to the length of a centrally-fixated grating up to a critical length value equivalent to 9–16 grating cycles, for a range of spatial frequencies; thereafter amplitude first decreased then increased with increasing length. VEP amplitude was proportional to log. contrast as well as to length, and the intercept of the regression line with the contrast axis coincided with the psychophysical threshold for gratings of different lengths. More sensitive measurements with lowcontrast stimuli around threshold indicated that in this range VEP amplitude is linearly related to contrast, and there is no threshold nonlinearity. The effects of visual field location and adaptation on the VEP to gratings of different lengths and spatial frequencies were also studied. The relationship of these findings to psychophysical, single-cell and transient VEP data is discussed.     

Objective measurement of contrast sensitivity using the steady-state visual evoked potential

Contrast sensitivity functions (CSFs) were determined electrophysiologically with the steady-state visual evoked potential (VEP). Psychophysical CSFs obtained by the method of increasing contrasts were also measured concurrently with the VEP trials. The VEP contrast thresholds were obtained using a rapid recording technique in which the contrast of a counterphase sinewave modulated at a temporal frequency of 7.5 Hz was swept from 0.5% to 40% over a period of 22 s in 39 equal logarithmic steps. For this pattern reversal stimulus, the amplitude and phase of the second harmonic response as a function of contrast were measured using a discrete Fourier transform (DFT). Contrast sensitivities at five spatial frequencies ranging from 0.5 to 14.9 cpd were measured. The VEP contrast thresholds were determined by a linear extrapolation to zero amplitude. The contrast threshold obtained by the two methods correlated at 0.816 for 14 subjects. For all five spatial frequencies there were no significant differences between the contrast sensitivities derived from the two methods.