正常闪光视网膜电图的频域分析

应用快速傅里叶转换技术对正常视网膜电图进行频域分析，发现其ａ、ｂ波的优势频及能量集中在５－７５Ｈｚ；与ＯＰＳ波的分离点为７７ＨＺ，从而提出单纯记录ａ、ｂ波及ＯＰＳ波各自的较理想的通频带。     

糖尿病性视网膜病变视网膜电图振荡电位的频域和时域分析

为分析早期和晚期ＤＲ患者ＥＲＧ的ＯＰｓ频域和时域参数，为ＤＲ的早期诊断和估计预后提供客观指标。测定和比较了１７只Ⅰ～Ⅱ期ＤＲ患眼、４５只Ⅳ～Ⅴ期ＤＲ患眼和４０只正常对照眼的ＯＰｓ频域和时域参数。结果：Ⅰ～Ⅱ期和Ⅳ～Ⅴ期ＤＲ患眼与正常对照眼比较，部分平均频谱的幅度、总功率、最大振幅和最大功率均有显著下降；ＯＰｓ四个子波的潜伏期均显著延长，振幅均显著下降，四个子波振幅总和显著下降；主频率只在Ⅳ～Ⅴ期组显著下降。Ⅳ～Ⅴ期与Ⅰ～Ⅱ期ＤＲ患眼比较，部分平均频谱的幅度、最大振幅和最大功率有显著下降；ＯＰｓ前两个子波的潜伏期有显著延长，四个子波振幅及其振幅总和均有显著下降。结论：ＯＰｓ的频域和时域参数可作为评价ＤＲ不同病程和估计预后的客观指标。     

正常大鼠视网膜电图振荡电位的频谱特性分析

背景暗适应视网膜电图（ERG）的振荡电位（OPs）在多种视网膜疾病的视功能评价中发挥重要作用,但其波形的确切起源尚未完全明确。OPs波的时域和频域分析及其影响因素的研究对进一步研究OPs的发生和起源具有重要意义。目的观察正常大鼠的暗适应ERGOPs与刺激光强度和动物年龄的关系。方法选择出生后21、25、32、35、37、46、60及90d的RCS—rdy^＋-P^＋大鼠各3只,采用RETI—scan记录系统进行闪光视网膜电图（F—ERG）OPs波记录,记录电极为环形角膜电极,参考电极为不锈钢针状电极,刺激强度分别为-20、-10、-5、0、5dB,通过Matlab提取OPs成分,分析其频谱特性。结果上述各种刺激强度下不同年龄组大鼠OPs的最大能量振幅值对应的频率值（即主频）范围为80～120Hz。随着刺激光强度的增加,开始出现高频（200—250Hz）成分,对应的振幅值随着刺激光强度的增加而增加;低频成分,即主频随着刺激光强度的增加其对应振幅值出现先升高后下降的趋势;当刺激光强度达到0dB时,低频成分出现双峰现象。25日龄大鼠OPs主频振幅最小,60日龄大鼠OPs主频振幅最大;25日龄大鼠OPs主频的带宽最窄,60日龄大鼠OPs主频的带宽最宽。结论大鼠ERG的OPs频域特性分析说明,刺激光强度对大鼠OPs振幅产生正向的影响,而大鼠的年龄主要影响OPs的主频分布。     

视网膜电图振荡电位波节个数分析

视网膜电图振荡电位波节个数分析解放军总医院眼科王红视网膜电图的振荡电位（ｅｌｅｃｔｒｏｒｅｔｉｎｏｇｒａｍｓ－ｏｓｃｉｌｌａｔｏｒｙＰｏｔｅｎｔｉａｌｓ，简称ＥＲＧ－ｏＰｓ），是一项视网膜生理功能的检查，它反映了视网膜的血液循环状态。ＯＰＳ是ＥＲＧ中...     

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。     

视网膜电图振荡电位及其在临床中的应用

视网膜电图的振荡电位 (oscillatory potentials,OPs)是叠加在 ERG b波上升枝的数个小而快的有节律的一串子波。6 0年代初期国外逐渐应用于眼科临床电生理检查中。较为公认的看法是 :振荡电位起源于内层视网膜 ,可能是代表从无长突细胞到双极细胞间的抑制性反馈回路。振荡电位对糖尿病视网膜病变的早期诊断 ,预测增殖性视网膜病变的危险性及提供激光治疗的适应证均具有重要意义。研究表明 ,振荡电位对中央静脉阻塞的早期诊断和分型是一种敏感而可靠的方法 ;振荡电位对静脉阻塞在判定病情及预后有着重要的意义 ;视网膜脱离患者患眼的振荡电位振幅降低甚或消失 ,峰时间延迟     

兔眼系列光视网膜电图振荡电位研究

用系列强度１３档刺激闪光记录３０例兔眼的视网膜电图和振荡电位，研究ＯＰｓ各子波的光强特性和参数特异性。结果表明，ＯＰｓ各子波振幅或峰时与刺激光强的函数关系为指数相关。其中，ＯＰ２峰时的相关性最高。不同对象间ＯＰｓ各子波振幅的变异系数较大，而峰时的变异系数较小。ＯＰｓ各子波的峰时改变比振幅发迹更为稳定，更具特异性。     

Electroretinographic Oscillatory Potentials in Different Aged Rats：an Analysis in the Domains of Time and Frequency

Objectives: Electroretinographic Oscillatory Potentials (Ops) are considered to be the optimal parameter to study the retinal circulation disturbances the present we compared parameters of OPs between different aged rats under dark adaptationMethods: the scotopic ERG were performed in anaesthetized rats aged 3, 12,24 months. According a window of collective power spectrum field of the OPs was isolated by using the FFT and IFFT of the spectrum analysis program. The parameters in the time and frequency domains were calculated.Results: Results showed that the amplitudes of wavelets and the summed amplitudes of OPs declined with the increase of age. A reduction of the total power and dominated power of OPs was also found after the FFT. But implicit time of each OP and dominant frequency did not change obviously.Conclusions: The present study indicated that change of OPs of rat might be related to senile degeneration of the retina and circulative deficiency in retina in elder rats. Eye Science 1998; 14-27 -2     

Analysis of Oscillatory Potentials of Flash Electroretinogram in Frequency Domain and Time Domain in Retinal Vein Occlusion

Purpose: To analyse the parameters of frequency domain and time domain of the OPs in branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). Methods : OPs from 9 eyes of BRVO, 9 eyes of CRVO and 40 normal control eyes were tested . The frequency spectra of the OPs were derived through Fast Fourier Transform (FFT) . The mean frequency spectra, the total power, the maximum magnitude, the maximum power and the dominant frequency in frequency domain of the OPs from the eyes of BRVO, CRVO and the normal control group were compared with each other. The OPs waveforms were reconstructed with the OPs frequency spectra data by counter-FFT. In time domain, the latencies, the amplitudes and the sum of the amplitudes of the four wavelets of OPs were measured and compared in the above subjects.Results: There were no statistically significant differences in the magnitudes of frequency spectra, the total power, the maximum magnitude and the maximum power in the frequency range from 110 to 250 Hz     

Electroretinographic evaluation in adult diabetics

In cross-sectional fashion, we recorded the maximal combined response and 30-Hz flicker responses in 178 adult diabetics and 40 normal controls according to the recommendations of the International Society of Clinical Electrophysiology of Vision. The oscillatory potentials were extracted from the maximal combined response by high-pass filtering. The clear media and attached retina were criteria for inclusion in this study. The data were statistically analyzed with the expectation that this procedure may provide a new feature that could have some clinical significance. Timing delays occurred more frequently than amplitude reductions in the maximal combined response and flicker responses, while amplitude reductions were more common in the first and second oscillatory potentials. The hypernormal b-wave amplitude was rare. The summed amplitude of the oscillatory potentials was highly correlated with the total power of the oscillatory potentials (the frequency domain). A reduction of the second oscillatory potential amplitude was more common than a reduction of the summed amplitude or total power. The electroretinographic component that demonstrates retinal dysfunction in the earlier stage may be a valuable indicator. In the early stage, a delay in the a-wave time and a reduction in the second oscillatory potential amplitude were the most frequent abnormalities: analysis of variance demonstrated that the summed amplitude of the oscillatory potentials and second oscillatory potential amplitude and time were the most sensitive measures of the diabetic retina. Hence, the second oscillatory potential amplitude may be the most sensitive and valuable indicator representing a quantitative measure of overall retinal dysfunction.     

Electroretinographic oscillatory potentials in diabetic retinopathy

The oscillatory potentials of the electroretinogram in dark and light adaptation were evaluated by Fourier transform in 87 diabetics and 74 age-matched controls. The study consisted of four groups: normal control, no observable diabetic retinopathy, background diabetic retinopathy and proliferative diabetic retinopathy. A reduction in the amplitude of each oscillatory potential, the summed amplitudes, the area and the total power of the oscillatory potentials as well as delayed implicit time of each oscillatory potential peak in dark and light adaptation could be found in patients with background diabetic retinopathy and proliferative diabetic retinopathy. The amplitude of oscillatory potential 4 in dark adaptation and the total power of the oscillatory potentials in light adaptation seemed to be affected in patients with no observable diabetic retinopathy. The implicit time of oscillatory potential 2 in dark adaptation was valuable to distinguish between patients with no observable diabetic retinopathy and background diabetic retinopathy.Abbreviations NC normal control - NDR no observable diabetic retinopathy - BDR background diabetic retinopathy - PDR proliferative diabetic retinopathy     

Extraction and modeling of the Oscillatory Potential: signal conditioning to obtain minimally corrupted Oscillatory Potentials

A method of extracting a temporally bounded component of a composite signal has been developed which minimizes data corruption in signal processing. The composite signal is windowed in the time domain, padding signals are attached, and finally, the conditioned signal is filtered to extract the component of interest. The method has been utilized to extract the Oscillatory Potential (OP) from the Electroretinogram (ERG). ERGs can contain impulse like transients, including flash artifacts and a-b wave transition, which may not be related to the Oscillatory Potential. Such transients will stimulate a filter, yielding its natural (filter) response and thus distort the actual OP signal. To avoid this effect, time-domain windowing and signal conditioning is used to extract the OP from the ERG. The extraction and modeling approach is applied to ERGs obtained from patients with recent monocular central retinal vein occlusion (CRVO). Model parameters clearly differentiate affected from fellow eyes and show subtle differences between eyes with benign and complicated outcomes.     

Oscillatory potentials of the slow-sequence multifocal ERG in primates extracted using the Matching Pursuit method

This study used the Matching Pursuit (MP) method, a time-frequency analysis, to identify and characterize oscillatory potentials (OPs) in the primate electroretinogram (ERG). When the slow-sequence mfERG from the macular region of the retina was matched with Gabor functions, OPs were identified in two distinct bands: a high-frequency band peaking around 150 Hz that contributes to early OPs, and a low-frequency band peaking around 80 Hz that contributes to both early and late OPs. Pharmacological blockade and experimental glaucoma studies showed that the high-frequency OPs depend upon sodium-dependent spiking activity of retinal ganglion cells, whereas the low-frequency OPs depend primarily upon non-spiking activity of amacrine cells, and more distal retinal activity.     

Changes of Oscillatory Potentials and Photopic Negative Response in Patients with Early Diabetic Retinopathy

Purpose

To investigate the clinical significance of the oscillatory potentials (OPs) and photopic negative response (PhNR) of the electroretinogram (ERG) in patients with early diabetic retinopathy.

Methods

One hundred two diabetic patients with diabetic retinopathy at different stages were examined. Thirty-two age-matched normal controls were also studied. Full-field maximal and photopic cone ERGs were recorded. The amplitudes and implicit times of the OPs, cone b wave, and PhNR were compared at the different stages of diabetic retinopathy.

Results

The a and b wave amplitudes of the maximal scotopic ERGs remained unchanged despite advancing stages of retinopathy, but the OP amplitudes were significantly attenuated even at an early stage of diabetic retinopathy. The amplitudes of both the PhNR and cone b wave were reduced at an early stage of diabetic retinopathy. Analysis of the receiver operating characteristic curves demonstrated that the amplitudes and implicit times of the OPs were more sensitive and specific than those of the PhNR in detecting changes of retinal function in the early stages of diabetic retinopathy.

Conclusions

The amplitudes of the OPs and PhNR progressively decrease with the progression of diabetic retinopathy. The PhNR amplitudes were reduced along with the cone b wave, indicating that earlier change of the PhNR in diabetic patients reflects reduced input to the retinal ganglion cell from the distal retina. The amplitudes and implicit times of the OPs are better indicators than those of the PhNR in detecting functional decreases in patients with early diabetic retinopathy.?Jpn J Ophthalmol 2006;50:367–373 © Japanese Ophthalmological Society 2006     

将图像傅里叶频谱分析应用于汉字视标的选择

目的 以汉字图像各空间频率的频谱能量相似为原则,筛选汉字作为汉字视力表的备选视标.方法 从2500个常用汉字中选取两类笔画数的汉字:少笔画数汉字(2、3、4画,共172个)和中笔画数汉字(7、8.9画,共890个).将其中的每个汉字制作成BMP图片格式.然后,利用傅里叶频谱分析,获取每个汉字图像各空间频率成分的频谱分布.以此分别对所有的少笔画数和中笔画数汉字的各空间频率的频谱能量求均值,将其作为参照值,采用聚类分析将汉字图像进行聚类来选取汉字.结果 与少笔画数和中笔画数汉字各空间频率的频谱能量均值相似的汉字分别为50和40个.结论 通过汉字图像的傅里叶频谱分析,以汉字图像的各空间频率的频谱能量相似作为筛选视标的主要原则,符合了视觉系统具有的傅里叶频谱分析特性.此方法应用于汉字视标的筛选具有重要的意义.