扫描翻转图像视觉诱发电位视力与对数视力表视力的比较

目的 对扫描图像视觉诱发电位视力(SPVER视力)与对数视力表视力进行比较。方法比较50例受试者的视力表和SPVER视力。在SPVER视力的测定中用了8个不同空间频率的光栅条纹连续扫描,所得数据经离散傅立叶分析后,获得振幅一空间频率曲线,并由外推法估计其视力。结果SPVER视力与视力表视力的总体相关系数r=0．699,在视力表视力大于0．5时,SPVER视力有低估现象,而在视力表视力小于0．5时SPVER视力有高估现象。结论SPVER视力与视力表视力有良好的相关性。由于视力表视力和SPVER视力所用于评估视力的指标不同,使两者结果不完全相同。     

图形翻转视觉诱发电位检查对白内障术后视力评估的价值

目的:探讨图形翻转视觉诱发电位(pattern reversal visual evoked potential,PRVEP)检查对白内障术后视力评估的价值。方法:回顾性分析2012-10/2013-05在同济医院眼科住院,并在白内障超声乳化术及人工晶状体植入手术前后接受PRVEP检查的的成年白内障患者72例114眼的病例资料,其中76眼为老年性白内障,38眼为并发性白内障。根据晶状体混浊程度及晶状体核硬度将数据分为两组:核硬度Ⅰ,Ⅱ,Ⅲ级为A组,核硬度Ⅳ,Ⅴ级为B组,应用统计学方法进行数据间的相关性分析。结果:A组:(1)术前:视力平均值为0.344,PRVEP检查P100波的潜伏期平均值为107ms,N75-P100波的振幅平均值为4.633μV;术后:视力平均值为0.672,PRVEP检查P100波的潜伏期平均值为104.37ms,N75-P100波的振幅平均值为4.400μV。(2)手术前后视力与P100波的潜伏期呈显著负相关(P<0.01);手术前后视力与N75-P100波的振幅呈显著正相关(术前P<0.01,术后P<0.05)。(3)手术前后视力改善行数与P100波的潜伏期变化值无相关性。B组:(1)术前:视力平均值为0.116,P100波的潜伏期平均值为118.905ms,N75-P100波的振幅值为1.650μV;术后:视力平均值为0.576,P100波的潜伏期平均值为108.429ms,N75-P100波的振幅值5.132μV。(2)术前视力与P100波的潜伏期呈现显著负相关(P<0.05),而术后视力与P100波的潜伏期没有相关性;手术前后视力与N75-P100波的振幅没有相关性。(3)手术前后视力改善行数与P100波的潜伏期变化值没有相关性。结论:由白内障手术前后两组视力与PRVEP的P100波的潜伏期及N75-P100波的振幅的相关性可知,PRVEP受患者术前视力(即屈光间质混浊程度)影响较大,PRVEP检查不能作为白内障术后视力预后的判断指标,白内障手术前的PRVEP检查没有临床意义。     

儿童图形翻转视觉诱发电位对远视性弱视视功能研究

目的:探讨图形翻转视觉诱发电位(PR-VEP)在远视性弱视检查中的应用价值。方法:采用TAIKTEC150型视觉电生理仪对远视性弱视儿童149例298眼及矫正视力正常的远视儿童27例54眼进行图形翻转视觉诱发电位检测,并对结果进行统计分析。结果:中,重度弱视组N75,P100,N145潜伏期均较对照组潜伏期延长,其差异均有显著性(P<0.01);轻中重3组N75,P100,N145潜伏期之间两两比较,差异亦有显著性(P<0.01),且随着弱视程度的增加,N75,P100,N145潜伏期逐渐延长,与其呈负相关(分别是r=-0.13,P<0.05;r=-0.186,P<0.01;r=-0.273,P<0.01)。结论:图形翻转视觉诱发电位能较为准确的判断远视性弱视儿童的视功能损害程度,可作为客观评估弱视儿童视功能的一种手段。     

扫描图像视觉诱发电位视敏 度

扫描图像视觉诱发电位视敏度是利用连续高速翻转的从低到高的多种空间频率的正弦光栅作为刺激图象,获得相对ＶＥＰ振幅和空间频率的坐标图,并用外推法将相关线外推到０反应振幅量来估计视敏度。     

扫描图形视觉诱发电位在视觉发育期儿童中的应用

背景 扫描图形视觉诱发电位(SPVEP)作为一种客观视功能检测技术,可被用于婴幼儿及合作度较差的成年人的客观视力测定.已有研究显示,振幅-视角对数( A-LogVA)回归方法可提高SPVEP推算视力的准确性. 目的 研究SPVEP在视觉发育期儿童中的应用,并比较两种不同的视力推断方法,即振幅-空间频率(A-SP)回归方法和A-LogVA回归方法在儿童,尤其是弱视儿童客观视力评估中的有效性和准确性.方法 选取3～12岁各种原因所致弱视儿童26例26眼为弱视组,同时选取与弱视组儿童年龄相匹配的正常儿童31人为正常组.检测其最佳矫正LogMAR视力,并使用视觉电生理仪检测SPVEP,选用0.99～12.89 cpd的10个不同空间频率正弦调制水平光栅连续刺激视网膜,结果经离散傅里叶分析后采用A-SP回归方法和A-LogVA回归方法计算SPVEP视力,对检测结果行相关性分析. 结果 在正常组,由A-SP回归方法和A-LogVA回归方法计算所得的SPVEP视力与LogMAR视力的相关系数分别为0.600 (P＜0.01)和0.733(P＜0.01),均数差异有统计学意义(F=113.173,P＜0.01).由A-SP回归方法所测得的SPVEP视力(A-SP视力)与LogMAR视力均数差值的绝对值为0.40±0.02,由A-LogVA回归方法所测得的SPVEP视力(A-LogVA视力)与LogMAR视力均数差值的绝对值为0.26±0.02,A-SP视力与A-LogVA视力均数差值的绝对值为0.14±0.02.在弱视组,由A-SP回归方法和A-LogVA回归方法计算所得的SPVEP视力与LogMAR视力的相关系数分别为0.134(P=0.515)和0.456(P＜0.05),均数差异有统计学意义(F=3.433,P＜0.05).A-SP视力与LogMAR视力均数差值的绝对值为0.07±0.05,A-LogVA视力与LogMAR视力均数差值的绝对值为0.12±0.05,A-SP视力与A-LogVA视力均数差值的绝对值为0.05±0.01.在不同视力段,SPVEP视力存在高估或低估现象. 结论 SPVEP可对正常视力及弱视儿童的客观视力进行评估,且A-LogVA回归方法推断所得客观视力更为准确.     

应用视觉诱发电位技术评估视力

目的:将诱发电位技术应用于视力的客观评定。方法:以最小信号视角、P100波幅和潜伏期作为受检眼的检测指标,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(包括P100波幅和潜伏期的变化)。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,建立了最小信号视角条件下P100波幅与视力间的回归方程,运用该方法对180眼视力的客观评估与国际标准视力表筛查结果比较无显著性差异。结论:应用在最小信号视角条件下P100波幅与视力的回归方程对受检者视力的评估切实可行、简便且能达到量化分析的目的。     

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。     

两种回归方法推算扫描视觉诱发电位客观推断视力的比较

背景扫描视觉诱发电位（SVEP）是一种客观视力的检测方法,虽然SVEP客观推断视力与主观视力之间存在着明显的相关性,但是两者之间并不完全吻合。研究显示,改进SVEP客观推断视力的推算方法可以提高推断视力的准确性。目的研究SVEP客观推断视力两种推算方法,即振幅-空间频率（A—SP）回归方法与振幅一视角对数（A-logVA）回归方法在客观视力评估中的准确性,探讨影响SVEP客观推断视力准确性的因素。方法对64例具有不同视力的113眼进行SVEP检测、主观小数视力和LogMAR视力检测,分别计算A—SP回归方法推算出的小数视力和LogMAR视力及A．10gVA回归方法推算出的小数视力和LogMAR视力,并对检测结果行相关性分析。使用重庆国特公司GT-2000n型视觉电生理仪检测SVEP,选用0．99～12．89cpd的10个空间频率水平正弦光栅连续刺激视网膜,经离散傅里叶分析获得A—SP回归曲线和A—logVA回归曲线,并将相关直线外推至0振幅处,获得SVEP客观推断视力。结果在小数视力评价系统中,A—SP回归方法和A-logVA回归方法推算出的回归线相关指数分别为0．663和0．705,主观小数视力与由A-SP回归方法推算所得的小数视力间呈正相关（r=0．620,P〈0．01）,主观小数视力与由A—logVA回归方法推算所得的小数视力间呈正相关（r=0．540,P〈0．01）。SP小数视力与VA小数视力间差异有统计学意义（Z=-8．688,P〈0．01）;在LogMAR视力评价系统中,A-SP回归方法和A—logVA回归方法推算出的回归线相关指数分别为0．733和0．715,主观LogMAR视力与由A-SP回归方法推算所得的LogMAR视力间呈正相关（r=0．710,P〈0．01）,主观LogMAR视力与由A-logVA回归方法推算所得的LogMAR视力间呈正相关（r=0．700,P〈0．01）。两种推算方法获得的LogMAR视力间差异有统计学意义（Z=-8．748,P〈0．01）。不同性别、眼别、病种以及年龄段中VALogMAR视力测试值的偏差差异均无统计学意义（χ2=2．171,P=0．338;χ2=0．976,P=0．614;χ2=6．032,P=0．420;χ2=14．720,P=0．257）。结论SVEP是检测客观视力较为有效的方法。但SVEP变异较大,就目前检测技术的稳定性与准确性而言,A—logVA回归方法推算出的客观视力较A—SP回归方法准确。     

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。     

A new method of extrapolating the sweep pattern visual evoked potential acuity

Purpose In order to compare the amplitude-spatial frequency (A-SP) regression method with amplitude-logVA (A-logVA) regression methods in extrapolating the sweep pattern visual evoked potential (SPVEP) acuity. Methods We measured SPVEPs in 21 children and three adults using sinusoidally-modulated horizontal gratings as stimuli. The responses were averaged and displayed through discrete Fourier transformations. SPVER acuity was then estimated by using both the SPVEP amplitude- spatial frequency function (A-SP function regression method) and the SPVEP amplitude-log visual-angle function (A-logVA function regression method). Furthermore, the Bailey Lovie logMAR chart was employed to define visual acuity. Curve estimates were calculated to derive a correlation index (R) for each method. Results There are significant differences (t = 2.71, P < 0.05) between the correlation indices of curves obtained using the A-logVA function (logarithmic model, 0.95 +/- 0.01) and that obtained by the A-SP function (inverse model, 0.92 +/- 0.02). The overall correlation coefficient (r) between logMAR acuity and acuity calculated by the A-logVA regression method was 0.32 (P < 0.05). The overall correlation coefficient (r) between logMAR acuity and acuity calculated by the A-SP regression method was 0.41 (P < 0.05). Paired t-tests show that SPVEP acuity from the A-logVA function was not significantly different from acuities of the logMAR function (t = 1.77, P = 0.09). The difference in their mean values is 0.14 +/- 0.08. However, SPVEP acuity calculated using the A-SP function regression method is significantly different from the acuity calculated from the logMAR function (t = 10.09, P < 0.01). The difference in their mean values is 0.41 +/- 0.04. Conclusions The amplitude-logVA function regression method is more accurate in estimating SPVEP acuity in normal subjects with good visual acuity.     

Methods of visual acuity determination with the spatial frequency sweep visual evoked potential

Purpose The spatial frequency sweep visual evoked potential (sVEP) is used to rapidly determine visual acuity in children or non-responsive patients. Two techniques have been used to separate signal from noise: (1) the 95% confidence interval for the signal amplitude (95% CI) or (2) the amplitude of a Fourier frequency adjacent to 2×the signal frequency (DFT). The purpose of this study is to determine if there is a significant difference in acuity estimates with these techniques.Methods Ten normal subjects (approximately 0.00logMAR acuity) and 11 patients with decreased visual acuity took part in this project. Stimulus production and data analysis were done with an Enfant 4010 (Neuroscientific Corp). Standard VEP recording techniques were employed. The stimulus was a horizontal-oriented, sine wave grating that swept up the spatial frequency spectrum (contrast 80%, temporal reversal rate 7.5Hz). Sweeps were repeated until the confidence intervals for the data were no longer decreasing. The Bailey LovielogMAR chart was used to determine visual acuity. A line was fit to the high spatial frequency data using either the 95% CI or the DFT as the noise estimate. By using these linear equations, acuity estimates were obtained at 0, 1, and 2V signal amplitudes.Results The average logMAR acuity for the subjects with normal acuity was –0.06±0.070 (SD). The sVEP acuity estimates were 0.08±0.098, 0.18±0.092, and 0.33±0.195 (0, 1, and 2V extrapolations) with the 95% CI used as noise and 0.07±0.100, 0.18±0.103, and 0.33±0.202 (0, 1, and 2V extrapolations) with the DFT used as noise. By using the average noise from the Fourier frequency as the extrapolation level, the acuity was 0.10±0.098logMAR. The averagelogMAR acuity for the subjects with decreased visual acuity was 0.67±0.306 (SD). The sVEP acuity estimates were 0.53±0.175, 0.66±0.171, and 0.88±0.295 (0, 1, and 2V extrapolations) with the 95% CI used as noise and 0.53±0.179, 0.65±0.176, and 0.86±0.268 (0, 1, and 2V extrapolations) with the DFT used as noise. By using the average noise from the Fourier frequency as the extrapolation level, the acuity was 0.57±0.186logMAR. No significant difference was found between the two acuity estimate techniques for all of the subjects (repeated measures ANOVA, p=0.16, F₂₀=2.131). The sVEP estimates of acuity to the 0V and noise levels were not significantly different from the logMAR acuity (paired t-test, all p values >0.05).Conclusions The results indicate that the sVEP acuity does not depend on the noise estimation technique. In agreement with prior studies, the sVEP acuity underestimates the logMAR acuity in normally sighted individuals by about an octave.     

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.     

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     

Cone-rod dysfunction in patients with unexplained reduction in visual acuity

Electrophysiologic tests were performed in 233 patients who complained of reduced visual acuity with no satisfactory clinical explanation. The functional integrity of the retina was assessed from the light-and dark-adapted electroretinogram., Macular function and conduction in the optic nerves were estimated from the flash visual evoked potentials. Of the 233 patients 78 were grouped together on the basis of the electrophysiologic and clinical findings. They were characterized by subnormal electroretinogram responses with the cone system more affected than the rod system. The flash visual evoked potential responses were of abnormal waveform and prolonged implicit times. Most of these patients exhibited normal fundi. The reduction in visual acuity, the degree of electroretinogram deficits and the pattern of the visual evoked potential responses were similar in both eyes of each, patient, indicating a symmetric disorder. Slight deterioration of visual acuity and electrophysiologic variables were observed in 37 of the patients who were followed up over a period of up to 8 years. The electrophysiologic findings indicate that about 20% of patients complaining of unexplained reduction in visual acuity were suffering from a diffuse retinal disorder affecting the peripheral retina as well as the macular region. On the basis of electrophysiologic findings and clinical symptoms, we suggest grouping these patients under a new entity: cone-rod dysfunction.     

闪光视诱发电位检查对白内障患者术后视力的预测

目的:评价术前闪光视诱发电位(flash visual evoked potential,FVEP)检查对白内障术后视力的预测价值.方法:试验组白内障患者95例130眼于术前1～3 d常规行FVEP检查,术后1wk复查FVEP,1mo复查最佳矫正视力(best corrected visual acuity,BCVA).对照组38例62眼.分析FVEP-P2波的振幅及潜伏期,并注重波型完整性的分析.结果:术前FVEP正常者78眼,术后视力改善者75眼(96.2%),无改善者3眼(3.8%).术前FVEP异常者52眼,术后视力改善者40眼(76.9%),无改善者12眼(23.1%).FVEP对白内障患者术后视力预测的假阳性率28.5%,假阴性率3.9%,预测可靠性66.9%(BCVA=0.3).各级晶状体混浊者FVEP的潜伏期和振幅差异无显著性,白内障术前与术后FVEP的潜伏期和振幅差异无显著性.FVEP的振幅与术后BCVA相关性较好.结论:白内障术前FVEP正常者高度提示术后视力预后良好,但术前FVEP异常者术后仍有76.9%视力提高.因此,在临床工作中对于术前FVEP异常的白内障患者,不应轻易放弃手术治疗.