Interspecies and gender differences in multifocal electroretinograms of cynomolgus and rhesus macaques

The purpose of this study is to ascertain whether inherent differences exist in the retinal function of two macaque species that are commonly used in experimental glaucoma investigations. We quantified and compared multifocal electroretinograms (mfERGs) from ocularly normal cynomolgus (n = 6) and rhesus (n = 8) monkeys. The stimulus array consisted of 103 equal-sized hexagonal elements, which subtended ±44° about the central visual axis. Mean luminance of the display was 100 cd/m². The first-order kernel (K1) and second-order (first slice) kernel (K2) of the mfERG were averaged into 4 rings radiating from the foveal element, and represented the central 56° of visual field. Fifteen and 30-element segments were used for K1 and K2 quadrant and hemiretinal response determinations, respectively. Response measures for the rings, quadrants, and hemiretinae included K1 amplitude and implicit time, and K1 and K2 oscillatory potentials (OPs) and response amplitude root mean square (RMS). Species, gender, and retinotopic differences were assessed with repeated measures analysis of variance (split plot design). K1 amplitudes of the N1 waves, K1 and K2 OPs and K2 amplitude RMS for the ring, quadrant, and hemiretinal mfERG waveforms were larger in rhesus than in cynomolgus monkeys. Rhesus males (as compared to rhesus females) and cynomolgus females (as compared to cynomolgus males) exhibited larger amplitudes and less delayed implicit times in the central retina. These results demonstrate that species-specific differences in retinal function are evident in cynomolgus and rhesus monkeys. There also were gender-associated differences that varied across species. Thus, investigators should exercise caution when data from species or gender are combined.     

正常食蟹猴不同适应时间视网膜电图的 变化

目的：研究明/暗适应时间对正常成年食蟹猴闪光视网膜电图（ERG）结果的影响。方法：实验研究。 选取3只成年食蟹猴,分别于暗适应20、40、60 min后用国际临床视觉电生理会标准参数刺激,常 规程序记录暗适应ERG,在暗适应40 min后,分别明适应1、5、10 min记录明适应ERG。采用单因 素方差分析比较各时间段振幅与潜伏期变化。结果：不同暗适应时间,a、b波和震荡电位OPs的潜 伏期差异均无统计学意义（F=0.052,P=0.949）,暗适应时间小于40 min时,a、b波和OPs的振幅随暗 适应时间增加而显著增大（F=50.800,P<0.001）;暗适应40 min时,振幅达到最大,且不再随暗适应 时间增加而增大（F=0.016,P=0.899）。明适应a、b波的潜伏期同样不受明适应时间的影响（F=0.980, P=0.381）,a、b波的振幅在明适应5 min后达到最大（F=4.789,P=0.036）且随时间延长趋于平稳 （F=0.135,P=0.717）。结论：在一定时间内,明/暗适应时间对食蟹猴闪光ERG结果影响较大,故对 食蟹猴暗适应ERG记录的时间不宜少于40 min,而明适应ERG在5 min后即可记录。     

Changes in the s-Wave of Multifocal Electroretinograms in Eyes with Primary Open-Angle Glaucoma

Purpose To determine whether the s-wave is present in the multifocal electroretinogram (mfERG) and whether it is altered in eyes with primary open-angle glaucoma (POAG).Methods A Visual Evoked Response Imaging System was used to record mfERGs from 15 eyes of 15 normal adults, as control eyes, and from 15 eyes of 15 patients with POAG. The stimulus consisted of 37 hexagonal stimulating elements with luminances of 200cd/m² (white), 66.6cd/m² (gray), and 4cd/m² (black). The white or black element was presented at five different base periods (bpds) from 13.3 to 213.3ms according to a binary m-sequence. In the intervals between the white and black (or white) elements, gray elements were inserted at 75Hz. The changes in the amplitude and implicit time of the s-wave of the all-trace waveform of the first-order kernel of the mfERG were compared with the mean deviation (MD) of retinal sensitivity in the whole visual field measured with a Humphrey Field Analyzer.Results The s-wave was present as a positive wavelet on the descending limb of the first-order kernel response of the mfERGs of all eyes with POAG. The s-wave amplitude increased with prolongation of the bpd, as occurs in normal eyes. The mean amplitudes of the s-waves at bpds of 53.3 and 106.7ms were significantly smaller in the eyes with POAG than in the control eyes. The correlation between the s-wave amplitude and the severity of disturbance in the entire visual field indicated by the MD was not significant in eyes with POAG.Conclusions The characteristics of the s-wave in glaucomatous eyes were the same as those in the control eyes, but the amplitude of the s-waves in POAG eyes was significantly lower than that in the control eyes. This suggests that ganglion cells may be involved in the development of the s-wave. When comparing the s-wave with static perimetry, more local responses of the s-wave and more local retinal sensitivity in the static perimetry will be appropriate. Jpn J Ophthalmol 2004;48:208–214 © Japanese Ophthalmological Society 2004     

Amplitude of the s-Wave of Multifocal Electroretinograms Can Indicate Local Retinal Sensitivity in Glaucomatous Eyes

Purpose To determine whether the amplitude of the s-wave on a multifocal electroretinogram (mfERG) is correlated with the degree of visual field depression in eyes with glaucoma.Methods Twenty patients (20 eyes) with glaucoma,ages 46 to 69 years, were studied. Twenty healthy volunteers (20 eyes) with normal intraocular pressure and with no eye diseases served as controls. The retinal sensitivities of the upper and lower visual fields of the glaucomatous eyes were determined with a Humphrey Field Analyzer. The severity of retinal sensitivity depression was rated as mild (Group A), intermediate (Group B), or severe (Group C). To record the s-wave, mfERGs were elicited by pseudorandom stimulation, with the stimulus alternating according to a binary m-sequence for base periods (bpds) of 13.3, 26.7, 53.3, 106.7, and 213.3ms. The mfERGwaves recorded from the upper and lower visual field were summed separately.Results In the control group, the s-wave in the summed mfERG was observed in all visual field halves at all bpds 53.3ms or longer. The s-wave amplitude at a bpd of 213.3ms was significantly larger than that at a bpd of 53.3ms (P < 0.05). The s-wave was also present in the glaucoma patients eyes, and the s-wave amplitude increased as the bpd increased. At bpds of 53.3, 106.7, and 213.3-ms, the mean s-wave amplitudes in Groups B and C were significantly smaller than those in the control group (P < 0.05, 0.01, and 0.05, respectively). At bpds of 53.3 and 106.7ms, the mean amplitude of the s-waves in Group C was significantly smaller than that in Group A (P < 0.05). At a bpd of 106.7ms, a significant correlation was observed between the retinal sensitivity and the s-wave amplitude (P < 0.05).Conclusions The significant correlation between the retinal sensitivity and the amplitude of the swave at a bpd of 106.7ms supports the suggestion that the s-wave originates from the retinal ganglion cells and their axons. The amplitude of the s-wave may serve as an objective indicator of the severity of retinal ganglion cell damage. Jpn J Ophthalmol 2004;48:215–221 © Japanese Ophthalmological Society 2004     

Exploration of Multifocal Rod Electroretinograms Recording in Human

Purpose:To est the feasibility of recording rod multifocal electroretinograms(ERG)in humans and observe appropriate recording conditions.Methods:Multifocal rod ERG were recorded using a stimulus array of 61 equalsized hexagons in two normal subjects after the dark adaptation.Flashes were blue(W47B). Blamk frames between two successive flashes of hexagons varied from 0 to 14.Length of the m-sequence,bandwidth,flash frequency,flash intensities and background intensities were changed to obtain appropriate recording conditions for the clinical use.Results:Multifocla rod ERG were celarly recordable and well formed.They had an early implicit time,very small negative wave and a late implicit time,large positive wave.The positive wave was bimodal,whose timing and waveform were similar to the full-field rodERG.The local response amplitudes can be suppressed with increase in flash frequency or background intensity,decrease in flash intensity or the size of stimulus elements.Conclusions:Multifocal rod ERG can be recorded in human and can provide topographical maps of retinal function that have clinical usage,2^12-1 m-sequence length 3F blank frames and 3-300Hz bandwidth were suggested to appropriate recording conditions.     

Slow-stimulated Multifocal ERG in High- and Normal-tension Glaucoma

Purpose: To study the ability and sensitivity of the slow stimulation multifocal ERG (mfERG) to detect glaucomatous damage. Methods: Right eyes of 20 patients with normal-tension glaucoma (NTG), 15 patients with high-tension glaucoma (HTG) and 15 healthy volunteers underwent testing with the mfERG (VERIS 4.1^TM). The central 50 degrees of the retina were stimulated by 103 hexagons (m-sequence: 2¹³-1, Lmax: 100 cd/m², Lmin: 1 cd/m², background: 50 cd/m²). Each m-sequence step was followed by 3 black frames (Lmax: < 1 cd/m²). Five response averages of the first order response component (KI) were analyzed: the central 7.5 degrees and the 4 adjoining quadrants. The amplitudes from the first minimum, N1, to the first maximum, P1, and from P1 to the second minimum, N2, were analyzed as well as the latencies of N1, P1, N2 and the latencies of 3 multifocal oscillatory potentials (mfOPs) with their maxima at about 73, 80 and 85 ms. Results: For each parameter the percentage of deviation from the mean of the control group was calculated. These values were then added for each individual to form a deviation index (DI). Seventeen patients (85.0%) with NTG and 3 patients (20.0%) with HTG showed a DI outside the normal range. The major changes were observed in the mfOPs of the NTG patients. MfOPs were then selectively filtered at 100–300 Hz and their scalar product was analyzed over an epoch of 68–105 ms. This confirmed that mfOPs differed significantly from the control in the central 7.5° and, for NTG, in the nasal field. With a logistic regression analysis the mfOPs had a sensitivity to differentiate 85% of the NTG patients and 73% of the HTG patients from normal. Conclusions: Under these conditions, the slow-stimulated mfERG can detect glaucomatous dysfunction in NTG (85.0%). The differences observed between NTG and HTG are in support of a different underlying pathomechanism.     

The outer and inner retinal function in patients with multiple evanescent white dot syndrome

Background:  To investigate the outer and inner retinal function in patients with multiple evanescent white dot syndrome (MEWDS).
Methods:  The retinal function of three subjects with MEWDS was investigated using one or a combination of full-field electroretinography (ERG), multifocal electroretinography (mfERG) or recording of multifocal oscillatory potentials (mfOP).
Results:  In case 1, the scotopic, maximal, photopic and flicker ERG responses of the two eyes were similar but the amplitudes of the dark- and light-adapted OPs were markedly reduced in the affected eye. In cases 2 and 3, the ERG responses were grossly reduced in amplitude and as expected the OPs were also diminished. However, using the mfERG a residual area of 'normal' retinal function in the affected eye was identified. The local OP, assessed by the mfOP, within the residual 'normal' retinal area was reduced as compared with the corresponding retinal area of the fellow unaffected eye. Subsequently, the mfERG responses of the 'normal' retinal area were also reduced.
Conclusion:  The OPs were reduced throughout the retina in patients with MEWDS, even in the area with a normal mfERG. The electrophysiological findings suggest that functional abnormality in MEWDS may occur initially in the inner retina and subsequently involves the outer retina.     

实验性暗点对多焦视网膜电图的影响

目的：探讨多焦视网膜电图（multifocal electroretinogram,mfERG)的敏感性及有效性。方法：采用刺激屏幕多部位同时遮盖的方法,观察了黑纸及0．3、0．6两种对数单位中性滤光片遮盖后形成的实验性绝对及相对暗点对8例正常眼103个六边形刺激时相应各部位mfERG的影响,并对连续4次检查之间未遮盖部位的mfERG参数进行了分析。结果：六边形被1／2及完全遮盖时,对相应部位mfERG N1、P1波振幅有显著影响,随着透光度的降低,mfERG振幅也逐渐降低。1／3遮盖时,对mfERG各指标无影响。4次重复检查之间,未遮盖部位mfERG各参数无显著差异。结论：mfERG是一种敏感的视觉电生理检查方法,并具有较好的重复性。用103六边形刺激时,mfERG可以检测到大于1／3六边形的暗点。     

Effects of antibiotics on the in vitro ERG of the albino rabbit

This study describes the effects of penicillin G (PC-G) potassium, PC-G sodium, cloxacillin sodium (MCIPC), disodium sulbenicillin (SBPC), cefazolin sodium (CEZ) and cefsulodin sodium (CFS) on the in-vitro electroretinogram (ERG) of the albino rabbit.The b-wave and oscillatory potentials (OPs) were unchanged by 0.1 mM PC-G potassium or PC-G sodium. The OPs were slightly suppressed by 0.3 mM of either drug. While the a- and b-waves were not deteriorated, the OPs were greatly suppressed by 1.0 mM concentration. The effect of PC-G on the ERG was characterized by a selective suppression of the OPs. The b-wave and OPs were not suppressed by 0.03 mM MCIPC. They were slightly suppressed by 0.05 mM MCIPC. The a-wave, b-wave and OPs were not deteriorated by 1.0 mM SBPC. The b-wave and OPs were suppressed by 3.0 mM or 6.0 mM SBPC respectively. These changes appeared to be dose-dependent. Since the b-wave and OPs were concomitantly suppressed by both MCIPC and SBPC, these antibiotics, unlike PC-G, did not selectively suppress the OPs. The b-wave and OPs were unchanged by 0.1 mM CEZ or CFS. The OPs were slightly suppressed by 0.3mM CEZ or CFS. CEZ or CFS of 1.0 mM did not deteriorate the a- and b-waves, but selectively suppressed the OPs. The effects of CEZ and CFS on the ERG were characterized by a selective suppression of the OPs. The above-described changes in the ERG were reversible.     

Distribution of oscillatory components in the central retina

This study examines the characteristics and the naso-temporal asymmetries of the higher-order oscillatory components of the multifocal electroretinogram (mERG). The magnitude of the mERG asymmetry and the mechanisms which produce it have not been studied previously. We recorded the mERG from seven normal observers using slow multifocal flicker and response filtering of 10–300 Hz. This permitted, without additional filtering, examination of the dominant first order component and the oscillation-rich components in the first and second order kernels. The oscillatory components in the two kernels had multiple peaks separated by about 6.8 ms, similar to those of conventional oscillatory potentials. Naso-temporal asymmetry of the three response components was analyzed in three groups (concentric rings around the fovea) spanning 1.5–10 deg of retinal eccentricity. The oscillation-rich components were, on average, approximately 14% larger in amplitude in the temporal retina than in corresponding nasal locations (p < 0.05) while the dominant first order component was not asymmetrically distributed. We tested the hypothesis that the asymmetry could be modeled as a combination of a retinal component (RC) and an optic nerve head component (ONHC) which varies in latency as a function of distance from the optic disc. We found that both oscillatory components and the dominant first order response could be decomposed into RCs and ONHCs that are symmetrically distributed. Thus, it appears that the naso-temporal asymmetries of the oscillation-rich components are produced primarily by the relative alignment and enhancement of RC and ONHC wavelets in the temporal retina, and misalignment and partial cancellation in the nasal retina. This revised version was published online in July 2006 with corrections to the Cover Date.     

视网膜电图振荡电位的振幅测定方法的探讨

通过对正常人ERG的振荡电位(OPs)的几种不同的测定方法的对比,了解了各种测定方法的OPs总振幅和O_1振幅与a波振幅的相互关系,从而提出了一种简便且又受a波振幅影响最小的OPs总振幅测定方法,并建议在临床工作中采用之。     

累及黄斑的孔源性视网膜脱离手术前后黄斑区光学相干断层扫描与多焦视网膜电图的变化

目的：观察累及黄斑区的孔源性视网膜脱离( RRD)患眼手术前后黄斑区光学相干断层扫描(OCT)与多焦视网膜电图（mfERG）表现的变化。 方法：回顾性研究。选择2013年9月至2014年7月在河南省眼科研究所确诊为累及黄斑的RRD并行巩膜扣带术的患者52例（52眼）,以对侧正常眼作对照。RRD患眼均行巩膜扣带手术治疗。手术前及手术后1周,术后1、3、6个月,进行OCT及mfERG检查,观察RRD患眼黄斑区微结构,以及黄斑区反应振幅密度及潜伏期的变化。采用t检验对术前患眼与正常眼进行比较,采用重复测景方差分析对患眼手术前后黄斑中心凹厚度变化与中央1环的N1、P1波反应密度和潜伏期比较分析;采用Pearson积矩相关分析法分析术后各时问点最佳矫正视力(BCVA)与黄斑中心凹厚度、中央1环的N1、P1波反应密度和潜伏期的相关性。 结果：所有患眼术后均成功复位。术前患眼黄斑中心凹厚度较正常眼明显增厚,为(534+44) μm,差异有统计学意义（t=17.127,P<0.05）,术后1周、1个月、3个月、6个月患者黄斑中心凹厚度,较术前明显降低,差异有统计学意义(P<0.01)。与正常眼相比较,术前患者中央1环Nl波和P1波振幅密度降低（t_N1=17.372、t_p1=23.943,P< 0.05）,潜伏期延长（t_Nl=5.291、t_Pl=7.306,P< 0.05）,差异均有统计学意义,术后1周、术后1、3、6个月中央1环N1波及P1波振幅密度较术前均提高（P<0.01）,潜伏期与术前差异无统计学意义。患者BCVA在术后1、3、6个月与黄斑中心凹厚度呈负相关(r=-0.801、-0.695、-0.643,P<0.05),l与中央1环N1波及P1波振幅密度呈正相关(r_N1=0.702、0.695、0.632,r_p1=0.811、0.713、0.648;P< 0.05),与潜伏期无相关性。 结论：OCT与mfERG可以客观综合观察RRD患者术后黄斑区的形态和功能,评估视网膜脱离后的手术疗效。     

正常人闪光视网膜电图的特征

目的:探讨闪光视网膜电图(flash electroretinogram,F-ERG)在正常人的变化规律,以获得正常参考值.方法:应用法国Metrovision公司生产的Vision Monitor视觉诱发系统检测正常人53例73眼.F-ERG的5个标准反应,包括暗适应25dB弱光刺激时的反应(来自于视杆细胞)、暗适应odB强光刺激时的反应、振荡电位、明适应白色标准闪光刺激时的反应(来自于视锥细胞)和明适应快速重复闪烁光刺激的反应.按照10岁为一年龄组分成4组:20～29岁,20眼;30～39岁,22眼;40～49岁,19眼;50～60岁,12眼.比较4个年龄组振荡电位总振幅和a波、b波的振幅及潜伏期.结果:F-ERG暗适应25dB弱光刺激时a波无明显反应,b波潜伏期为1102±113ms,振幅为226.7±492μV;暗适应odB强光刺激时a波潜伏期为263±12ms,振幅为.205.4±40.1μV,b波潜伏期为49.3±2.3ms,振幅为481.2±81.2μV;明适应白色标准闪光刺激时a波潜伏期为23.0±1.6ms,振幅为-23.4±9.1μV,b波潜伏期为38.8±1.8ms,振幅为77.4±21.2μV;明适应快速重复闪烁光刺激b波的振幅为122.1±27.51μV;震荡电位总振幅为112.6±28.2μV.随着年龄的增加,振荡电位总振幅和其余4个标准反应的b波振幅逐渐降低,a波振幅与年龄的增加无明显相关性,50～60岁年龄组a、b波的潜伏期较其他组延长,但各年龄组两两比较无显著统计学差异(P＞0.05).结论:确定了正常人F-ERG的5个标准反应的正常值,并比较了振荡电位总振幅和a,b波振幅及潜伏期与年龄的关系,振荡电位总振幅和b波振幅随着年龄的增加逐渐降低,a波振幅与年龄的增加无明显相关性,50-60岁年龄组a,b波的潜伏期较其他组延长,但各年龄组两两比较无显著统计学差异(P＞0.05).     

Effects of Adenosine Agonists on Intraocular Pressure and Aqueous Humor Dynamics in Cynomolgus Monkeys

The effects of single or multiple topical doses of the relatively selective A₁adenosine receptor agonists (R)-phenylisopropyladenosine (R-PIA) and N⁶-cyclohexyladenosine (CHA) on intraocular pressure (IOP), aqueous humor flow (AHF) and outflow facility were investigated in ocular normotensive cynomolgus monkeys. IOP and AHF were determined, under ketamine anesthesia, by Goldmann applanation tonometry and fluorophotometry, respectively. Total outflow facility was determined by anterior chamber perfusion under pentobarbital anesthesia. A single unilateral topical application of R-PIA (20–250 μg) or CHA (20–500 μg) produced ocular hypertension (maximum rise=4.9 or 3.5 mmHg) within 30 min, followed by ocular hypotension (maximum fall=2.1 or 3.6 mmHg) from 2–6 hr. The relatively selective adenosine A₂antagonist 3,7-dimethyl-1-propargylxanthine (DMPX, 320 μg) inhibited the early hypertension, without influencing the hypotension. Neither 100 μg R-PIA nor 500 μg CHA clearly altered AHF. Total outflow facility was increased by 71% 3 hr after 100 μg R-PIA. In conclusion, the early ocular hypertension produced by topical adenosine agonists in cynomolgus monkeys is associated with the activation of adenosine A₂receptors, while the subsequent hypotension appears to be mediated by adenosine A₁receptors and results primarily from increased outflow facility.     

Microelectrode depth study of the electroretinographic oscillatory potentials in the frog retina

The depth profile of the electroretinographic oscillatory potentials was studied in the isolated frog retina. The intraretinal electrode was introduced from the receptor side, and the reference electrode was placed on the vitreal side. The electroretinogram, recorded either transretinally or with the electrode tip in the receptor layer, showed 4 to 10 oscillatory potential wavelets. As the electrode was advanced proximally, the wavelets disappeared as a function of retinal depth. The wavelets with longer peak latencies disappeared earlier, and only the first one or two wavelets could be identified when the electrode was in the inner plexiform layer. These findings indicate that the oscillatory potentials are generated between the inner and outer plexiform layers and that the earlier wavelets originate in the more proximal retina. The results are consistent with the notion that the oscillatory potentials are generated by synaptic feedback circuits.     

The effect of iodoacetic acid on the electroretinogram and oscillatory potentials in rabbits

It has been shown that a single injection of iodoacetic acid selectively (but temporarily) abolishes the b-wave of the electroretinogram. We examined whether such use of this chemical further substantiate our claim that the b-wave of the electroretinogram is a composite potential resulting from the summation (or integration) of faster retinal potentials, usually referred to as the oscillatory potentials. Full-field electroretinograms were recorded from adult New Zealand rabbits before and after a single, bolus injection of 15mg/kg of buffered iodoacetic acid. Both the 1–1000 Hz electroretinogram and the 100–1000 Hz oscillatory potentials were recorded simultaneously. The oscillatory potentials considered in this study were those normally seen on the rising phase of the b-wave. Following the intravenous injection of iodoacetic acid, there was a progressive decrease in the amplitude and peak time of the b-wave. This observation also was reflected in the oscillatory potential recordings, in which the long-latency oscillatory potentials (3 and 4) progressively disappeared while oscillatory potential 2 remained. We believe that these findings further support our contention that the oscillatory potentials are major components of the b-wave.     

视觉电生理技术在青光眼早期诊断中的意义

青光眼是一组威胁和损害视神经及其视觉通路,最终导致视觉功能损害的疾病。青光眼视神经损害以视网膜神经节细胞( retinal ganglion cells,RGCs)及其轴突数目进行性丢失、视盘凹陷、视野缺损为特征。静态自动视野计检查是评估青光眼病程进展的金标准,但其结果往往受到患者主观因素的限制。近年来视觉电生理技术飞速发展,虽还不能代替传统的视野检查,但作为补充,其能在青光眼视野缺损前即出现振幅及潜伏期的改变,为早期青光眼的诊断提供了新的参考思路。本文主要对三种特殊类型的视网膜电图以及多焦视觉诱发电位在青光眼早期诊断中的意义进行综述。     

The action of peptides on the mudpuppy electroretinogram (ERG)

Two neuropeptide substances were applied to the mudpuppy retina while the electroretinogram (ERG) was recorded. A low concentration of somatostatin (10(-9)M) was found to be a potent agent in increasing the amplitudes of all the oscillatory potentials (OPs) of the ERG. There was no appreciable change of the threshold sensitivity or the stimulus response curve of the b-wave. The highest concentration tested (10(-6)M) reduced the first OP to about the same amplitude as at the start of the experiment and attenuated the later OPs. A decrease of the suprathreshold b-wave was induced by the highest concentrations (10(-7), 10(-6)M) of somatostatin. A low concentration of substance P (10(-11)M) selectively and differentially decreased the earlier OPs (O1O2). Higher concentrations (10(-10), 10(-9)M) diminished the earlier OPs further, reduced the later OPs and decreased the supra-threshold a- and b-waves. The results support previous suggestions that the OPs reflect activities in feedback circuits initiated by the amacrines and indicate that somatostatin and substance P through separate mechanisms seem to interact with the inhibitory neuronal circuits which have been suggested to give rise to the OPs. Secondly, in agreement with previous work, the OPs appear to have a different origin from the b-wave. Thirdly, two separate classes of amacrines, each with a different transmitter, seem to be associated with different physiological roles.     

Effects of refractive blur on the multifocal electroretinogram

A significant difference in the response density of the MF-ERG response has been suggested for every 2 diopter change of refraction. The influence of refractive blur on the MF-ERG was studied in 8 healthy volunteers using either the VERIS™ system (Group A: n=5) or Retiscan™ (Group B: n=3). For each eye recordings were obtained with a corrective lens of −3 dpt, 0 dpt, +3 dpt and +6 dpt placed in front of the contact lens electrode. The viewing distance was adjusted to compensate for the induced changes in the retinal image size. When the changes in retinal image size due to the refractive lens were compensated for, no influence due to refraction was observed in either latencies or amplitudes of (KI (P>0.05). This held true for the central response average (four degrees) as well as for the outer 6–25 degrees. In KII.1 only the peripheral amplitudes of Group B showed an influence due to refraction (P≤0.05). This may be due to adaptation as the recordings of group B were obtained in succession. As expected, significant differences were observed when the recordings obtained with the different systems were compared (P≤0.05). This revised version was published online in July 2006 with corrections to the Cover Date.     

高血糖对实验性糖尿病大鼠视网膜电图的影响

目的观察糖尿病大鼠ERG和OPs的变化情况,探讨糖尿病对大鼠FERG和OPs的影响。方法将100只大鼠分为正常组10只和糖尿病组90只。糖尿病组用STZ造模,6个月后将符合条件的大鼠纳入观察组。检测6、9个月时大鼠ERG和OPs的表现。结果糖尿病大鼠视网膜电图a波、b波、OPs振幅有下降趋势,峰潜时延长,与对照组大鼠相比有差异(P<0.01);9个月时糖尿病大鼠a波、b波、OPs振幅降低,峰潜时延迟,与6个月时比较有显著差异(P<0.01或0.05)。结论高血糖可使糖尿病大鼠ERG和OPs振幅下降,峰潜时延长;且随病程的延长其影响逐渐增强。