利用锥体细胞失功能大鼠和先天性静止性夜盲大鼠对视锥与视杆通路振荡电位的分离研究

背景 振荡电位(OPs)是评估视网膜缺血缺氧性疾病视网膜功能变化的重要工具,利用视网膜退行性病变动物模型对视锥、视杆通路起源的OPs特点进行研究非常重要. 目的 在两种自发性视网膜退行性病变模型大鼠中分离视锥、视杆通路,对比分析视杆、视锥通路起源的OPs波的特点. 方法 采用雄性SD大鼠、锥体细胞失功能(RCD)大鼠、先天性静止性夜盲(CSNB)大鼠各6只,以RETI-scan视觉生理记录系统分别在暗适应(12h)和明适应(10 min)条件下,用不同强度的刺激光(-35、-25、-15、-5、0、5 db)进行刺激,记录各组大鼠的闪光视网膜电图(FERG),通过Matlab 7.0的Butterworth滤波提取OPs,采用快速傅里叶变换(FFT)对所得OPs进行频谱分析.结果 暗适应条件下SD大鼠和RCD大鼠的ERG均可见a波和b波,但CSNB大鼠b波阙如;明适应条件下,SD大鼠和CSNB大鼠可见b波,但RCD大鼠各波阙如.暗适应较高刺激光强度下,SD大鼠和RCD大鼠均有低频(主频)和高频(次频)两个明显的频峰,分别为75 ～ 110 Hz、90～120 Hz和90～ 120 Hz、110 ～ 135 Hz;不同刺激光强度下,CSNB大鼠只有一个频峰,为70～100 Hz.而明适应不同刺激光强度下,SD大鼠和CSNB大鼠均只有一个频峰,分别为75～95 Hz和70～85 Hz.明适应条件下与SD大鼠比较,CSNB大鼠b波隐含时延长,b波振幅明显下降,差异均有统计学意义(P＜0.05);暗适应条件下,RCD大鼠b波隐含时和振幅与SD大鼠比较,差异无统计学意义(P＞0.05);与SD大鼠比较,RCD和CSNB大鼠OPs波振幅下降,隐含时延长,差异均有统计学意义(P＜0.05);明适应条件下不同刺激光强度下CSNB大鼠OPs波的隐含时明显长于SD大鼠,振幅明显低于SD大鼠,差异均有统计学意义(P＜0.05). 结论 视锥、视杆通路起源的OPs有不同特性,自发性视网膜退行性改变大鼠的视杆OPs有两个频峰,正常情况下,视杆通路对OPs的贡献比视锥通路大.     

植入电极记录豚鼠图形视觉诱发电位

目的探讨用植入电极方式记录豚鼠图形视觉诱发电位(pattern visual evoked potential,PVEP)的方法。方法豚鼠麻醉后,暴露颅骨表面,在前囟(Bregma)前6mm、后10mm及矢状缝正中处钻孔,均植入长5mm、直径为1.2mm的不锈钢螺钉,分别作为参考电极、记录电极和地极。3d后,将清醒状态下的豚鼠固定于自制多功能头身一体化固定台面上,银-氯化银电极连接于豚鼠体表的不锈钢螺钉上,采用RETI-port系统(Roland Consult,德国)分别记录不同空间频率和不同颜色下的图形视觉诱发电位。结果植入电极后,在无出血感染条件下,实验豚鼠生存时间与正常豚鼠没有明显区别。在其清醒状态下可以记录到豚鼠的PVEP波形,呈NPN形状。空间频率对PVEP波形有明显的影响:随着空间频率的增加,N1、P1波的潜伏期都有不同程度的延长,当空间频率大于0.5cpd时,潜伏期延长明显;随着空间频率的增加,振幅降低。在不同对比度(97%、60%、30%)下,P1波的振幅随着对比度的增加而提高,且任意两个对比度之间P波振幅的差异均有统计学意义(P<0.05)。在97%和60%的对比度下,潜伏期差异无统计学意...     

Improving reproducibility of VEP recording in rats: electrodes,stimulus source and peak analysis

The aims of this study were to evaluate and improve the reproducibility of visual evoked potential (VEP) measurement in rats and to develop a mini-Ganzfeld stimulator for rat VEP recording. VEPs of Sprague–Dawley rats were recorded on one randomly selected eye on three separate days within a week, and the recordings were repeated three times on the first day to evaluate the intrasession repeatability and intersession reproducibility. The VEPs were recorded with subdermal needle and implanted skull screw electrodes, respectively, to evaluate the effect of electrode configuration on VEP reproducibility. We also designed a mini-Ganzfeld stimulator for rats, which provided better eye isolation than the conventional visual stimuli such as flash strobes and large Ganzfeld systems. The VEP responses from mini-Ganzfeld were compared with PS33-PLUS photic strobe and single light-emitting diode (LED). The latencies of P1, N1, P2, N2, and P3 and the amplitude of each component were measured and analysed. Intrasession and intersession within-subject standard deviations (Sw), coefficient of variation, repeatability (R₉₅) and intraclass correlation coefficient (ICC) were calculated. The VEPs recorded using the implanted skull electrodes showed significantly larger amplitude and higher reproducibility compared to the needle electrodes (P < 0.05). The mini-Ganzfeld stimulator showed superior repeatability and reproducibility in VEP recording. The intra/intersession ICCs of latency were 0.85/0.70 for mini-Ganzfeld, 0.72/0.62 for PS33-PLUS and only 0.59/0.42 for single LED. The latencies of the early peaks (N1 and P2) demonstrated better reproducibility than the later waves. The mean intrasession and intersession ICCs were 0.96 and 0.86 for the early peaks. Using a combination of skull screw electrodes, mini-Ganzfeld stimulator and early peak analysis, we achieved a high reproducibility in the rat VEP measurement. The latencies of the early peaks of rat VEPs were more consistent, which may be due to their generation in the primary visual cortex via the retino-geniculate fibres.     

多焦视诱发电位地形图

目的阐明多焦视诱发电位成分是如何从多通道双极记录中得出和进行地形学分析的.并研究不同的视皮层记录位置对多焦视诱发电位的波形、潜伏期(ms)和振幅(mV)的影响.方法采用多通道罗兰电生理系统(Retiscan,Wiesbaden/Brandenburg,Germany)分别测量50位正常人双眼不同视野的多焦视诱发电位(visual evoked potential,VEP)(最大的离心率为30°).两眼分别给予刺激.伪随机改变的刺激由多通道罗兰系统产生.刺激图形由60个刺激扇形组成,每个扇形又含16个方格,8个白色方格(＞130 cd/m2)和8个黑色方格(＜2 cd/m2).各个刺激单元的刺激翻转由一个伪随机序列控制.电极放置参照双极枕叶电极放置法,同时从4个前-后矢状中线及4个水平连线(横贯枕叶视皮层)上的皮肤电极上记录视觉诱发电位波形.上述电极可以是正极或负极.结果在记录的枕叶皮层区,不同记录通道所记录的VEP显示了不同的平均峰潜伏期和振幅值.在矢状中线上记录到的mVEP,其最大振幅值小于水平线上的记录值.另外,刺激视网膜不同部位所诱发的电位在头皮的位置是不同的.结论双极枕叶电极在矢状中线上记录到的mVEP与视野地形图记录的有良好的相关性.双极记录位置负极在枕骨粗隆,而正极在枕骨粗隆矢状轴上2 cm或4cm或正极在枕骨粗隆水平左、右4 cm时,记录得到的VEP结果更具可比性.为了更准确地评估客观视野缺损,可进行上下1/2或者水平1/2的多焦VEP记录.     

遗传性视网膜病变模式大鼠的氧诱导视网膜病变观察

目的:探索遗传性视网膜病变模式大鼠的氧诱导视网膜新生血管特点。方法:将新生(生后7d)的SD大鼠、CSNB大鼠和RCD大鼠各1窝每窝(即每组)6只暴露于800±20mL/L氧浓度环境中持续饲养5d,然后再回到正常氧环境条件饲养5d;对照组为以上3种品系同龄新生鼠各1窝,每窝(即每组)各6只置于正常氧环境中饲养17d作为对照。在第18d时将所有幼鼠行心脏墨汁灌注,取出两侧眼球,其中1眼用于视网膜铺片了解视网膜血管形态的改变,另1眼用于组织切片观察并统计突破视网膜内界膜的血管内皮细胞核的数目。结果:在正常饲养环境下,RCD大鼠视网膜血管网稀疏,SD大鼠CSNB大鼠视网膜血管未见明显异常。在氧诱导下,各实验组大鼠视网膜血管正常网络状结构受到破坏,结构稀疏,血管迂曲、收缩或扩张,部分血管出现闭塞,其中SD大鼠、CSNB大鼠视网膜有出血点,甚至片状出血。组织切片显示对照组的SD大鼠中偶见突破内界膜的内皮细胞核,其他两组均未见。实验组中SD大鼠、CSNB大鼠和RCD大鼠3种品系中均可见较多的突破内界膜内皮细胞核,计数结果分别为24.10±2.49,38.20±10.47,68.00±3.06,与同品系的对照组有显著性的差异(P<0.01);与不同品系的实验组比较也均有显著性差异(P<0.01)。结论:氧诱导的新生大鼠视网膜新生血管与品系有关,视网膜退行性病变大鼠仍可诱导出视网膜新生血管,且严重程度可能与感光细胞的功能有关。     

Prediction of visual evoked potentials at any surface location from a set of three recording electrodes

Purpose of this study was to introduce a mathematical model which allows the calculation of a source dipole as the origin of the evoked activity based on the data of three simultaneously recorded VEPs from different locations at the scalp surface to predict field potentials at any neighboring location and to validate this model by comparison with actual recordings. In 10 healthy subjects (25–38, mean 29 years) continuous VEPs were recorded via 96 channels. On the base of the recordings at the positions POz′, O1′ and O2′, a source dipole vector was calculated for each time point of the recordings and VEP responses were back projected for any of the 96 electrode positions. Differences between the calculated and the actually recorded responses were quantified by coefficients of variation (CV). The prediction precision and response size depended on the distance between the electrode of the predicted response and the recording electrodes. After compensating this relationship using a polynomial function, the CV of the mean difference between calculated and recorded responses of the 10 subjects was 2.8 ± 1.2%. In conclusion, the “Mini-Brainmapping" model can provide precise topographical information with minimal additional recording efforts with good reliability. The implementation of this method in a routine diagnostic setting as an “easy-to-do" procedure would allow to examine a large number of patients and normal subjects in a short time, and thus, a solid data base could be created to correlate well defined pathologies with topographical VEP changes.     

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。     

Implantation of stimulation electrodes in the subretinal space to demonstrate cortical responses in Yucatan minipig in the course of visual prosthesis development

PURPOSE: During the course of the development of visual prostheses, subretinal stimulation films were implanted in micropigs in order to prove the feasibility of subretinal electrical stimulation with subsequent cortical response. One aim was to demonstrate that epidural recording of visual evoked potentials is possible in the micropig. METHODS: Film-bound stimulation electrode arrays were placed in the subretinal space of micropigs. This enabled the retina to be stimulated subretinally. Since conventional visual evoked potential (VEP) measuring is virtually impossible in the pig from the neurosurgical point of view, epidural recording electrode arrays were positioned over the visual cortex as permanent electrodes. RESULTS: The feasibility of temporary implantation of film-bound stimulation electrode arrays was successfully demonstrated in the micropig model. On stimulation with monopolar voltage pulses (1000 to 3000 mV), reproducible epidural VEP measurements (5 to 10 micronV) were detected. CONCLUSIONS: The feasibility of subretinal stimulation of the retina was demonstrated in a retinal model that is similar to the human retina. This animal model therefore offers a suitable means of studying the tolerability of stimulation situations in the course of visual prosthesis development.     

Multifocal pattern VEP perimetry: analysis of sectoral waveforms

Purpose: The objective detection of local visual field defects using multi-focal pattern visual evoked potentials (VEP) has recently been described. The individual waveforms show variable polarity in different parts of the visual field due to underlying cortical convolutions. Normal trace arrays were examined to determine if certain areas of similar waveform could be grouped for analysis, while minimising cancellation of data. Method: The VEP was assessed using multi-focal pseudo-randomly alternated pattern stimuli which were cortically scaled in size. Bipolar occipital electrodes were used for recording. Waveforms were compared for different locations within the field up to 25° of eccentricity. Analysis of sectors showing similarly shaped waveforms was performed. Twelve normal subjects were studied. Result: Grouping waveforms by sectors of similar waveform increased the total calculated upper hemifield amplitude by 60%, compared with simple summations of responses for the whole hemifield. The inferior hemifield showed more consistent waveforms throughout, with the amplitude only increasing by 11% with sectoral summation. Intra-subject variability (10.6%) is less for sectors than for individual points (17.3%). Inter-subject amplitude differences are high, calculated at 56% for individual points and 45% for sectors. Conclusions: Due to differences in waveform as a result of underlying cortical anatomy, individual VEP responses from multifocal recordings should be grouped as sectors along the vertical meridian and above and below the horizontal, rather than by hemifields or quadrants. This finding is significant if one is considering within-field grouping strategies similar to the glaucoma hemifield test used in conventional perimetry, or reporting derived overall VEP amplitudes and latencies from a multifocal recording. Large amplitude variations between individuals and small signals from horizontal and upper field seen in single channel recording, still limit the application of this technique as a form of objective perimetry. This revised version was published online in July 2006 with corrections to the Cover Date.     

Implantation and testing of subretinal film electrodes in domestic pigs

By definition, an electronic subretinal visual prosthesis requires the implantation of stimulation electrodes in the subretinal space of the eye. Polyimide film electrodes with flat contacts were implanted subretinally and used for electrical stimulation in acute experiments in anaesthetised domestic pigs. In two pigs, the film electrode was inserted through a sclerostomy into the vitreous cavity and, subsequently, via a retinotomy into the subretinal space around the posterior pole (ab interno approach). In three other pigs the sclera and pigment epithelium were opened for combined ab interno and transscleral positioning of the subretinal electrode. In all cases, perfluorocarbon liquid (PFCL) was used to establish a close contact between the film electrode and the outer retina. After cranial preparations of three pigs for epidural recording of visual cortex responses, retinal stimulation was performed in one pig with a film electrode implanted ab interno and in two pigs with film electrodes implanted by the ab interno and transscleral procedure. The five subretinal implantations were carried out successfully and each polyimide film electrode tip was positioned beneath the outer retina of the posterior pole. The retina was attached to the stimulation electrode in all cases. Epidural cortical responses to light and electrical stimulation were recorded in three experiments. Initial cortical responses to Ganzfeld light and to electrical stimuli occurred about 40 and 20 ms, respectively, after stimulation onset. The stimulation threshold was approximately 100 microA and, like the cortical response amplitudes, depended both on the correspondence between retinal stimulation and cortical recording sites and on the number of stimulation electrodes used simultaneously. Our results in a domestic pig model demonstrate that polyimide film electrodes can be implanted subretinally and tested by recording cortical responses to electrical stimulation. These findings suggest that the domestic pig could be an appropriate animal model for basic testing of subretinal implants.     

兔眼玻璃体视网膜界面结构与相关生理参数

目的:观测兔眼正常玻璃体视网膜界面(VRI)基本的结构及相关生理。方法:新西兰大白兔20只,应用皮肤及角膜接触镜电极作为记录电极,测定其视网膜电图(ERG),记录其b波振幅(bA)值,并对其中4只眼的VRI结构进行组织病理学检查。结果:正常的VRI包括紧密相邻的玻璃体后皮质(PVC)和视网膜内界膜(ILL),并有其各自的特点;两种记录电极得到的正常兔眼双侧ERG的bA值无统计学差异(P>0.05)。结论:正常兔眼VRI的基本结构由PVC与ILL组成;ERG的bA值能较好地反映视网膜的生理功能。     

先天性静止性夜盲大鼠视杆双极细胞L-钙通道电生理特征

目的研究先天性静止性夜盲（CSNB）大鼠视杆双极细胞（RBCs）L-钙通道的生理学特征,探讨其与视觉信号传导通路障碍的关系。方法选取4～8周龄SD大鼠20只（对照组）、CSNB大鼠23只（实验组）,深度麻醉后处死大鼠,制作视网膜切片,红外显微镜下寻找RBCs胞体,运用全细胞膜片钳模式记录L-钙通道电流,并记录程序刺激后细胞静息膜电容（restCm）的变化值（△Cm）,计算胞吐系数（EI）。结果对照组L-钙通道电流于-20～-30mV达到峰值（-33.2±2.5）pA,实验组电流于-15mV左右达峰值,为（12.2±2.3）pA;L-钙通道特异性阻断剂nifedipine（10μm）可以完全阻断所记录的钙电流。GABA受体阻断剂PTX（100μm）能够明显阻断实验组除极时诱发的外向电流。与对照组比较,实验组的△Cm和EI均明显降低（P〈0.01）。结论 CSNB大鼠双极细胞L-钙通道电生理特征的改变会严重影响其向下级神经元释放神经递质,这可能是导致CSNB发病的机制之一。     

A potential spontaneous rat model of X-linked congenital stationary night blindness

Purpose: To describe a possible spontaneous rat model of X-linked congenital stationary night blindness (CSNB). Methods: Experimental animals were generated by mating the affected animal to normal rats, and from interbreeding littermates. To define the inheritance pattern, full-field electroretinograms (ERGs) were recorded from all progeny. Results: During the course of other experiments, an affected male rat was identified by a reduced amplitude ERG b-wave. When this rat was mated to normal Sprague–Dawley rats, all of the F1 progeny had normal ERG waveforms. When F1 offspring were interbred, 51% of the male offspring had b-wave reductions while all female offspring had normal ERG waveforms. When F1 females were backcrossed to the original affected male, b-wave reductions were noted in both male and female offspring; overall, 46.8% of the backcross progeny exhibited a b-wave reduction. In affected animals, the b-wave was selectively affected as the a-wave appeared to retain normal amplitude and kinetics at 1–4 months old. Cone ERGs were significantly reduced in amplitude and somewhat delayed. Similar ERG results were also obtained under the same stimulus conditions from human patients with complete CSNB (CSNB1). Conclusions: The inheritance pattern is consistent with an X-linked recessive trait. The electrophysiological results suggest that this mutant rat line may provide another model for CSNB1.     

Psychophysical assessment of low visual function in patients with retinal degenerative diseases (RDDs) with the Diagnosys full-field stimulus threshold (D-FST)

Quantification of visual function is essential for the impact of disease models and their treatment. Recently, we introduced a chronic implant model to record visual evoked potentials (VEP) in awake Brown–Norway rats. Here, we investigated the hemispheric distribution of VEP after monocular stimulation, the chronic electrode implantation and the influence of commonly used anesthetics. Potentials were recorded by electrodes, implanted epidurally over the superior colliculus. The entire visual field of the rat was stimulated. Flicker stimuli were modulated in luminance with a modulation depth from 5 to 80% at 7.5 Hz and flashes with a modulation depth of >95% in a frequency range of 2.9–38 Hz. Recordings were constant over 9 days. When one eye was blinded, the potentials recorded from the contralateral side were not affected, while the potentials of the ipsilateral side were markedly reduced. Further, potentials of awake animals were compared with those receiving general anesthetics. For one group of rats (n = 8), we administered isoflurane by inhalation in five concentrations. Four different groups (n = 7–11) were given choralhydrate (200 and 400 mg/kg) and the combination of ketamine/xyaline (65/7 or 130/14 mg/kg, respectively) intraperitoneally. Isoflurane depressed the VEP in a concentration-dependent manner. Treatment with chloralhydrate and ketamine/xyaline increased the VEP at low concentrations and depressed it in high concentrations. The new VEP paradigm assesses distinct qualities of contrast vision in rats. All tested narcotics alter VEP amplitudes and can be avoided.     

Influence of Recording Electrode Type and Reference Electrode Position on the Canine Electroretinogram

Electroretinography is commonly used to assess the functional integrity of the retina. There are many external variables that can influence the electroretinographic waveforms recorded, and it is important to be aware of these so as not to misinterpret their effects as abnormalities in retinal function. In this study we examined the effect of three different recording electrodes on the ERGs recorded from normal dogs. A bipolar Burian–Allen lens, a monopolar Dawson Trick Litzkow (DTL) fiber electrode, and a monopolar ERG-Jet lens electrode were compared. The effect of altering the distance of the reference electrode from the eye was also examined; using the ERG-Jet lens electrode, the ERG was recorded with the reference electrode placed over the zygomatic arch at 1, 3 and 5 cm caudal to the lateral canthus. The ERGs recorded with the bipolar Burian–Allen lens had significantly lower amplitudes, higher a-wave thresholds and a shallower initial a-wave slope, than those recorded by the two monopolar electrodes. Positioning the reference electrode further from the eye resulted in significantly higher amplitudes. Naka-Rushton fitting and calculation of retinal sensitivity (K) gave significantly different results between the Burian–Allen lens and ERG-Jet lens electrode with the reference electrode 5 cm from the lateral canthus. These results demonstrate that recording electrode type and distance of the reference electrode from the eye significantly affect the ERG tracings of the dog, and may alter the assessment of retinal function that can therefore be derived. Results obtained using these three different types of electrodes cannot be directly compared.     

人工泪液对大鼠视网膜电图的影响

目的 观察人工泪液对大鼠视网膜电图（ERG）的影响.方法 动物实验研究.SD大鼠充分暗适应后,记录单眼ERG.ERG记录采用自制银丝电极和不锈钢针状电极,其中银丝电极为记录电极,置于角巩膜缘,各组ERG记录眼人工泪液用量不同：第1组为未滴人工泪液组;第2组为适量组,滴少量人工泪液,使电极与角巩膜缘接触良好;第3组为过量组,滴入大量人工泪液,使之充满整个结膜囊.ERG a、b波幅值和峰时采用单因素方差分析比较组间差异,两两间差异采用LSDt法进行比较.结果 使用人工泪液的两组动物ERG基线平滑,干扰波不明显;然而人工泪液使用过量组a、b波振幅均明显降低,与其他两组相比差异均有统计学意义（t=4.112,P＜0.01;t=3.018,P＜0.05）.结论 视觉电生理实验室经屏蔽和有效接地后,动物ERG记录中使用人工泪液可以进一步降低干扰,但人工泪液使用过量会影响ERG振幅大小.     

Is Optic Nerve Fibre Mis-Routing a Feature of Congenital Stationary Night Blindness?

Purpose: To determine whether patients with congenital stationary night blindness (CSNB) have electrophysiological evidence of optic nerve fibre mis-routing similar to that found in patients with ocular albinism (OA). Method: We recorded the Pattern Onset VEP using a protocol optimised to detect mis-routing of optic nerve fibres in older children and adults. We tested 20 patients (age 15–69 yrs) with X-linked or autosomal recessive CSNB, 14 patients (age 9–56 yrs) with OA and 13 normally pigmented volunteers (age 21–66 yrs). We measured the amplitude and latency of the CI component at the occipital midline and over left and right occipital hemispheres. We also assessed the computed inter-hemispheric “difference” signal. Subjects with CSNB were classified as having the “complete” or “incomplete” phenotype on the basis of their ERG characteristics. Members of X-linked CSNB pedigrees underwent mutation screening of the NYX and CACNA1F genes. Results: CI was significantly smaller over the ipsilateral hemisphere and more prominent over the contralateral hemisphere in OA patients compared with both controls and CSNB patients. In CSNB patients CI response amplitudes were not significantly different from controls but peak latency was prolonged at all three electrodes compared with controls. The inter-hemispheric “difference” signal was abnormal for the OA group but not for the CSNB group. Contralateral dominance of CI could be identified in the majority of OA patients and the “difference” signal was opposite in polarity for left compared with right eye stimulation in every patient in this group. Only 3 of 20 patients with CSNB showed significant inter-hemispheric asymmetry similar to that seen in the OA patients. All 3 CSNB patients with evidence for optic nerve fibre mis-routing had X-linked pedigrees: 2 had an identified mutation in the NYX gene but no mutation in either the NYX or CACNA1F genes was identified in the third. VEP evidence of optic nerve fibre mis-routing was present in 3 of the 11 subjects with “complete” phenotype and none of the 9 patients with “incomplete” phenotype CSNB. Conclusion: Mis-routing of optic nerve fibres does occur in CSNB but we found evidence of it in only 15% of our patients.     

A technique for recording the electroretinogram (ERG) from chronically implanted electrodes in animals

A technique is described for recording the electroretinogram in monkeys from electrodes surgically implanted in the supraorbital bone. Recordings from these electrodes evidenced response wave-forms which had a high correlation with those recorded simultaneously from a corneal-wick electrode. The technique described should prove to be more convenient than the corneal wick for prolonged recording sessions or repeated measurements from the same animal and also permits recordings to be obtained in an unanesthetized preparation.     

不同记录电极位置对多焦视诱发电位检查结果的影响

目的 比较不同记录电极位置对多焦视诱发电位(mf-VEP)检查结果的影响。 方法 应用RETIscan多焦视诱发电位记录系统3.20对10例正常人进行检查。记录电极位置包括两组垂直通道和两组水平通道。垂直通道作用电极和参考电极分别置于枕骨隆凸上、下方各2.0 cm（Ch1）或枕骨隆凸上方3.0 cm、下方4.5cm (Ch2)；水平通道作用电极和参考电极分别置于枕骨隆凸右、左侧各2.0 cm（Ch3）或4.0 cm (Ch4)。分别比较各通道记录的上半视野及下半视野mf-VEP的振幅之和有无显著性差异。 结果 各通道记录的上半视野及下半视野mf-VEP振幅之和的差异均有显著性的意义（F=20.273, P=0.000）；且Ch2与Ch1、Ch3、Ch4两两之间的差异也有显著性的意义（P分别为0.000 、0.000、0.001）。对于沿水平中线分布的位点，Ch2记录的mf-VEP中振幅很小的各位点的振幅之和，与Ch3、Ch4记录的mf-VEP中相应位点的振幅之和的差异有显著性的意义（F=11.304,P=0.000）；且Ch4与Ch2、Ch3两两之间的差异也有显著性的意义（P均<0.05）。 结论 与Ch1、Ch3和Ch4相比, Ch2可记录到更佳的mf-VEP。水平通道可改善垂直通道对部分位点，尤其是沿水平中线分布位点的mf-VEP的引导，其中Ch4对Ch2的改善作用较Ch3更为明显。 （中华眼底病杂志，2004，20：346-348）     

Safety and efficacy evaluation of a new ERG electrode (the LVP electrode); Part II. Flash ERG pilot study

A new disposable, non-contact electrode (LVP electrode) was evaluated for use in recording flash ERG. A comparison of DTL and LVP electrodes showed reproducible waveforms for all components analysed. There was a good correlation obtained between the DTL and LVP electrodes. The LVP electrode is safe, less expensive and has less movement of the fiber due to its rigidity.