Multifocal electroretinogram responses in Nepalese diabetic patients without retinopathy

Purpose

To determine neuroretinal function with multifocal electroretinogram (mfERG) in diabetic subjects without retinopathy.

Methods

Multifocal electroretinogram (mfERG) was performed in 18 eyes of 18 diabetic subjects without retinopathy and 17 eyes of 17 age and gender-matched healthy control participants. Among 18 diabetic subjects, two had type 1 and 16 had type 2 diabetes. MfERG responses were averaged by the retinal areas of six concentric rings and four quadrants, and 103 retinal locations; N1–P1 amplitude and P1-implicit time were analysed.

Results

Average mfERG N1–P1 amplitude (in nv/deg²) of 103 retinal locations was 56.3 ± 17.2 (mean ± SD) in type 1 diabetic subjects, 47.2 ± 9.3 in type 2 diabetic subjects and 71.5 ± 12.7 in controls. Average P1-implicit time (in ms) was 43.0 ± 1.3 in type 1 diabetic subjects, 43.9 ± 2.3 in type 2 diabetic subjects and 41.9 ± 2.1 in controls. There was significant reduction in average N1–P1 amplitude and delay in P1-implicit time in type 2 diabetic subjects in comparison to controls. mfERG amplitude did not show any significant correlation with diabetes duration and blood sugar level. However, implicit time showed a positive correlation with diabetes duration in type 2 diabetic subjects with diabetes duration ≥5 years.

Conclusions

This is the first study in a Nepalese population with diabetes using multifocal electroretinography. We present novel findings that mfERG N1–P1 amplitude is markedly reduced along with delay in P1-implicit time in type 2 diabetic subjects without retinopathy. These findings indicate that there might be significant dysfunction of inner retina before the development of diabetic retinopathy in the study population, which have higher prevalence of diabetes than the global estimate and uncontrolled blood sugar level.     

亚临床期糖尿病视网膜病变的多焦视网膜电流图

多焦视网膜电流图(multifocalelectroretinogram,mERG或mfERG)是一种新兴的眼科检查手段,通过使用特殊m-序列刺激手段短时间内提取局部ERG信号,客观、定量地反映视网膜功能。糖尿病引起的眼部并发症是糖尿病患者致盲的一个主要原因,能够在亚临床期早期诊断糖尿病视网膜疾病(diabeticretinopathy,DR),对于预防和治疗DR有着重要的意义。mERG能够客观地检测DR,应用于研究和临床,评估那些预防和治疗DR方法的效果。     

Multifocal electroretinogram delays predict sites of subsequent diabetic retinopathy

PURPOSE: To examine the potential of abnormal mfERGs to predict the development of diabetic retinopathy at corresponding retinal locations 1 year later. METHODS: One eye of 11 diabetic patients with nonproliferative diabetic retinopathy (NPDR) and 11 diabetic patients without retinopathy were retested 12 months after initial testing. At each time, mfERGs were recorded from 103 retinal locations, and fundus photographs were taken within 1 month of each recording. Local mfERG implicit times were measured and their z-scores were calculated based on results obtained from 20 age-matched control subjects. mfERG abnormalities were defined as z-scores of 2 or more for implicit time and z-scores of -2 or less for amplitude (P < or = 0.023). mfERG z-scores were mapped onto fundus photographs, and the relationship between baseline abnormal z-scores and new retinopathy at follow-up was examined. RESULTS: New retinopathy developed in 7 of the eyes with NPDR after 1 year. In these eyes, 70% of the mfERGs in areas of new retinopathy had abnormal implicit times at baseline. In contrast, only 24% of the responses in regions that remained retinopathy free were abnormal at baseline. Relative risk of development of new retinopathy over 1 year in the areas with abnormal baseline mfERG implicit times was approximately 21 times greater than that in the areas with normal baseline mfERGs (odds ratio = 31.4; P < 0.001). Eyes without initial retinopathy did not develop new retinopathy within the study period, although 4 of these 11 eyes had abnormal implicit times at baseline. mfERG implicit times tended to be more delayed at follow-up than at baseline in NPDR eyes, but not in eyes without retinopathy and control eyes. mfERG amplitudes had no predictive power. CONCLUSIONS: Localized functional abnormalities of the retina reflected by mfERG delays often precede the onset of new structural signs of diabetic retinopathy. Those functional abnormalities predict the local sites of new retinopathy observed 1 year later.     

眼底无可见视网膜病变的糖尿病患者多焦视网膜电图特征

目的 检测眼底无视网膜病变糖尿病患者的多焦视网膜电图(multifocol electmretinogram, mf-ERG),评价其在糖尿病患者早期视网膜功能改变中的作用.方法 应用mf-ERG检测30例(56只眼)正常对照组和32名(58只眼)无眼底镜下可查见的视网膜病变的糖尿病患者.对两组mf-ERG中a波和b波的潜伏期、振幅总和以及b波的振幅密度进行分析比较.结果 在糖尿病组,除0环和颞下象限之外.b波的潜伏期均明显延迟,而a波和b波振幅总和及b波的振幅密度减低主要集中在黄斑周围区域(0～1环)和颞上象限,差别有统计学意义(P<0.05).结论 mf-ERG能在DR出现之前客观定量地评定视网膜功能的变化程度和范围.     

Multifocal electroretinogram in diabetic subjects

PurposeTo identify local retinal abnormalities and evaluate the nature and extent of retinal dysfunction in diabetics using full field electroretinogram (ERG) and multifocal ERG (MF-ERG) and to determine the correlation between features of optical coherence tomography (OCT) and MF-ERG.MethodsTwenty-eight normal subjects (Control Group; 56 eyes) and 37 patients (72 eyes) with diabetes mellitus (DM Group) were evaluated. In the DM Group, 17 eyes had no retinopathy (grade 1), 18 eyes had early non proliferative diabetic retinopathy (NPDR) (grade 3), 16 eyes had late NPDR (grade 4), 21 eyes had proliferative diabetic retinopathy (PDR) (grade 5). Full field ERG and MF-ERG, were used to assess the effects of diabetic retinopathy on retinal function. OCT and fluorescein angiography were used to assess and compare morphological changes with functional changes in diabetes mellitus.ResultsIn diabetic patients without retinopathy (17 eyes), the amplitudes of the second order component of MF-ERG were reduced and implicit times were delayed, while only implicit times of first order component of MF-ERG were delayed but the amplitudes of first order component were normal. In diabetic patients with retinopathy (55 eyes), the overall amplitudes were reduced and peak implicit time increased in the first order component and second order component.OCT of the DM Group showed the fovea of eyes with edema were thicker than the Normal Group. The fovea of eyes with cystoid macular edema (CME) were significantly thicker than the fovea of eyes with diffuse swelling. The implicit times of MF-ERG were directly correlated with foveal thickness.ConclusionMF-ERG reveals local retinal dysfunction in diabetic patients. MF-ERG offers the advantage of topographic mapping of retinal dysfunction. The magnitude of delay of MF-ERG implicit time reflects the degree of local clinical abnormalities in eyes with retinopathy. Local response delays found in eyes without retinopathy detects subclinical local retinal dysfunction in diabetics. The combination of OCT and MF-ERG may provide objective criteria for evaluation and assessment of diabetic retinopathy.     

Multifocal electroretinogram delays reveal local retinal dysfunction in early diabetic retinopathy.

PURPOSE: To identify local retinal abnormalities in diabetic patients with and without retinopathy, by using the multifocal electroretinogram (M-ERG). METHODS: Electroretinograms were recorded at 103 discrete retinal locations in each eye of eight persons with nonproliferative diabetic retinopathy (NPDR) and eight diabetic persons without retinopathy, using VERIS (EDI, San Mateo, CA). The amplitude and implicit time of each local (first-order) retinal response were derived and compared with normal values obtained from 16 age-matched, nondiabetic subjects. Maps of local response amplitude and implicit time were compared with fundus photographs taken at the time of testing. RESULTS: In eyes with NPDR, the implicit times of responses from retinal sites manifesting clinical pathologic fundus lesions (e.g., microaneurysms and focal edema), were markedly delayed (e.g., up to 7 msec from normal). Responses from adjacent retinal sites that were more normal in clinical appearance were also delayed, but to a lesser extent (e.g., 2-5 msec). Smaller, yet significant local response delays were also found in eyes without retinopathy. By contrast, local response amplitudes bore no consistent relationship to fundus abnormalities in eyes with retinopathy, and amplitudes were typically normal in eyes without retinopathy. CONCLUSIONS: The M-ERG reveals local retinal dysfunction in diabetic eyes even before retinopathy. The magnitude of delay of local ERG implicit time reflects the degree of local clinical abnormality in eyes with retinopathy. Local response delays found in some eyes without retinopathy suggest that the M-ERG detects subclinical local retinal dysfunction in diabetes. Analysis of M-ERG implicit time, independent of amplitude, improves the sensitivity of detection of local retinal dysfunction in diabetes.     

多焦视网膜电图及彩色多普勒在糖尿病视网膜病变早期诊断中的应用比较

目的 比较多焦视网膜电图（mfERG）与彩色多普勒在糖尿病视网膜病变（DR）早期诊断中的应用.方法 采用横断面研究,运用mfERLG检测正常对照组22例（22眼）、糖尿病无DR组52例（52眼）及DR单纯期组32例（32眼）.在上述患者中运用彩色多普勒测量视网膜中央动脉（CRA）的血流.采用单因素方差分析方法以及S-N-K法进行统计学分析.结果 糖尿病患者中,无DR组mfERG环1至环3中P1波反应密度低于正常对照组（P＜0.05）;CRA的血流则无异常变化（P＞0.05）.在DR单纯期组,mfERG除上述指标异常以外,Pt波潜伏期也出现延长（P＜0.05）.CRA的流速比正常对照组及无DR组降低（P＜0.05）.结论 在DR的临床早期诊断中,mfERG比彩色多普勒检测CRA血流的方法更敏感.     

Effect of short-term hyperglycemia on multifocal electroretinogram in diabetic patients without retinopathy

PURPOSE: To investigate the effect of variations in blood glucose level on the multifocal electroretinogram (mfERG) in patients with type 1 diabetes without retinopathy. METHODS: Fourteen patients were clamped sequentially and in random order at 5 and 15 mM blood glucose for 75 minutes on the same day. MfERG was recorded in one eye at each level of blood glucose level. RESULTS: Compared to euglycemia (5 mM), hyperglycemia was associated with an overall decrease in the implicit times and an increase in the amplitudes of the multifocal ERG. The effect of hyperglycemia on implicit time reached statistical significance for the summed first positive (P1) and second negative component (N2) of the first-order kernel (P = 0.0020 and 0.0005, respectively) and all components of the second-order kernel (P = 0.014, 0.0037, and 0034, respectively). These changes in the mfERG demonstrated no significant variation in relation to retinal location or long-term blood glucose level. CONCLUSIONS: Steady-state hyperglycemia induced shorter first- and second-order kernel implicit times in patients with type 1 diabetes without retinopathy. The effects of hyperglycemia were not significant with retinal location. These results support the hypothesis that hyperglycemia accelerates retinal metabolism.     

无视网膜病变的糖尿病患者多焦视网膜电图的变化

目的通过采用多焦视网膜电图（mfERG）对正常对照组、尚未出现视网膜病变的糖尿病患者进行检测，了解mfERG发现糖尿病早期视功能变化的能力。方法采用mfERG进行视功能检测，所有受检者分为33例（33只眼）正常对照组以及63例（63只眼）糖尿病组，其中糖尿病组患者均无视网膜病变。对2组mfERG中N1波与P1波的反应密度与潜伏期进行比较。结果mfERG在糖尿病视网膜病变发生前已有异常，主要表现为环1、环2的P1波反应密度以及环1-环3与环5的N1波反应密度降低。结论mfERG能够在糖尿病视网膜病变出现之前，客观定量地发现早期视功能的变化程度与范围。     

The electroretinogram in diabetic retinopathy.

Electroretinography (ERG) is an objective method of evaluating retinal function. Since its introduction to clinical practice in the 1940s, it has become a useful and routine diagnostic clinical tool in ophthalmology. This review summarizes the role of ERG as a clinical technique for evaluating the progression of diabetic retinopathy and as a research tool for increasing our understanding of the pathophysiology of diabetic retinopathy. Most studies show unequivocally that the different types of ERG tests detect local abnormalities or widespread pathology, even in very early stages of the disease. It seems plausible that measurements from ERG recordings, particularly the oscillatory potentials, may be useful for predicting progression from nonproliferative to the more sight-threatening stages--preproliferative or proliferative--of diabetic retinopathy. Some recent work implies that the ERG can also be a useful diagnostic method for discriminating between eyes with diabetic retinopathy and those without the condition.     

黄斑病变患者多焦视网膜电图的变化

目的:观察黄斑病变多焦视网膜电图穴mERG雪特点,探讨mERG在黄斑功能测定中的有效性。方法:应用德国罗兰视觉诱发反应成像系统,对黄斑病变71 眼与正常人48眼进行mERG测定,记录103个视网膜部位的一阶反应(first orderkernel,FOK)比较分析视网膜后极部不同区域a波和b波的平均反应密度值和潜伏期,并观察其三维图的改变。结果:黄斑病变患者1～3环a、b波平均反应密度下降,与正常值比较有显著差异。5、6环平均反应密度下降,无显著差异。1～6环a、b波平均潜伏期较正常组明显延长,三维图形上主要特征为中心凹及黄斑振幅明显降低,严重者反应呈平坦。结论:mERG能客观地对黄斑病变局部视网膜功能进行定量定位测定,是评价黄斑病变的一种有效客观检测手段,为疾病诊断和治疗效果客观的测定提供了一种有效方法。     

The electroretinogram in minimal diabetic retinopathy.

The pattern and diffuse flash electroretinograms were measured in 20 normal subjects and 40 diabetic patients who had either normal fundi or microaneurysms only. The amplitudes of the pattern electroretinogram were found to be similar in both normals and diabetics. In the case of the flash electroretinogram the diabetic patients showed a division into two main groups. One group was not dissimilar to the group of normal subjects, while the second group showed hypernormal amplitudes. No explanation could be given, from the data collected, for this subdivision, though it is suggested it might reflect the degree of metabolic disturbance.     

早期糖尿病视网膜病变的视网膜电图分析

目的 分析早期糖尿病视网膜病变(DR)的闪光视网膜电图(F—ERG)和视网膜电图震荡电位(OPs)各参数的变化特点，寻找反映早期DR的敏感指标。方法 对16例(32只眼)正常人进行OPs和F-ERG检测。对27例(53只眼)糖尿病病人进行眼底荧光血管造影(FFA)、OPs和F—ERG检测。结果 OPs中Os波幅、O4波幅、OPs总波幅及F-ERG中b波峰潜时较其他指标敏感，其中O4波幅和b波峰潜时为最敏感指标，但均不能反映早期DR的严重程度。结论 OPs的O4波幅和F—ERG的b波峰潜时可作为早期糖尿病视网膜病变诊断的敏感指标。     

糖尿病视网膜病变患者的多焦视网膜电图研究进展

糖尿病视网膜病变(diabetic retinopathy,DR)是糖尿病患者主要的眼部并发症,可以导致视力的严重损害.多焦视网膜电图是一项新的视觉电生理测量方法 ,能在相对较短的时间内测量整个测视野中许多细小部位的视网膜电图,可以反映局部视网膜的功能,对于DR的早期诊断具有极其重要的价值,并且能够定量地监测DR的进展情况,判断疗效和预后.     

白内障超声乳化吸出术后多焦视网膜电图变化

目的:采用多焦视网膜电图(multifocalelec-troretignroam,mfERG)评价年龄相关性白内障患者行超声乳化白内障吸出术后视网膜功能的改变。方法:应用法国Metrovision公司生产的VisionMonitor视觉诱发系统检测23例23眼年龄相关性白内障超声乳化术后及8例11眼同龄正常对照眼的mfERG,检测视野的水平视角±30°,垂直视角±23°,采用ERG-jet接触镜电极,于5min记录61个视网膜部位的反应。结果:与正常对照组比较,白内障术后组mfERG的N1波潜伏期在各视网膜半区、4个象限及第2～5环延长,差异有显著性意义;P1波潜伏期在视网膜上半区、颞侧区、颞上象限、颞下象限和第2～4环延长,差异有显著性意义;N2波潜伏期在视网膜下半区、颞下象限及第2～4环明显延长,差异亦有显著性意义。术后组N2波振幅密度在视网膜颞侧区、颞上和颞下象限降低,与对照组比较差异有显著性意义。结论:白内障术后眼mfERG的一阶kernal反应有明显改变,为进一步研究白内障患者视网膜的功能提供参考。     

糖尿病视网膜病变黄斑区视网膜厚度与mERG的观察研究

目的探讨糖尿病视网膜病变(DR)黄斑区视网膜厚度与多焦视网膜电图(mERG)的变化及相互关系。方法采用视网膜厚度分析仪(RTA)对34例(68眼)糖尿病患者及mERG对23例(45眼)糖尿病患者进行检测。结果从无视网膜病变的糖尿病(NDR)患者到Ⅰ期、Ⅲ期DR患者的黄斑区视网膜厚度呈增加趋势,Ⅲ期DR患者的黄斑区各部位视网膜厚度均较正常对照组增加,经统计学分析差异有显著性意义(P<0.01或0.05);且与视力呈显著负相关(P<0.05)。Ⅰ期DR患者的P1波及N2波反应密度较NDR患者减少(P<0.01或0.05),Ⅲ期DR患者的N1波、P1波、N2波潜伏期分别较NDR患者或Ⅰ期DR患者延长,各波反应密度分别较NDR或Ⅰ期DR患者减少(P<0.01或0.05)。中心凹区视网膜平均厚度与P1波潜伏期及反应密度呈显著相关(P<0.05);黄斑区及旁中心凹区的视网膜平均厚度与N2波反应密度及潜伏期呈显著相关(P<0.01或0.05)。结论当黄斑区视网膜厚度增加时,相应的视网膜功能出现损害,RTA结合mERG的检查,可更加全面地反映DR患者黄斑区视网膜的变化。     

增生型糖尿病视网膜病变多焦视网膜电图的观察分析

目的:观察增生型糖尿病视网膜病变(proliferative diabetic retinopathy,PDR)的多焦视网膜电图(multifocal electroretinogram,mf-ERG)的图像特征及临床意义.方法:对临床确诊的PDR患者40例44眼(PDR组)和正常对照组40例40眼进行mf-ERG检查,并对所得数据进行统计分析.结果:PDR患者组mf-ERG 1~5环的反应密度均低于正常对照组,且有显著性差异,N1波潜伏期在4环、P1波潜伏期在2~5环与正常对照组相比显著延长.结论:Mf-ERG可有效地评价PDR患者视网膜的功能.