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1.
Previous studies of early diabetic retinopathy have shown that oscillatory potential (OP) amplitudes are reduced in many diabetic patients. OP amplitude is believed to be a more sensitive indicator of the development of future retinopathy than b-wave amplitude of the scotopic electroretinogram (ERG). Because OPs measured to a bright white flash reflect both rod and cone system activity, it is important to compare OP amplitudes to photopic ERG measures as well as scotopic measures in early diabetic retinopathy. In this study, OPs and ERG responses were measured under photopic and scotopic conditions in a group of diabetic patients. Although OPs were reduced in amplitude in the diabetic group, several other parameters of the scotopic and photopic b-waves were impaired. The results indicate that b-wave activity may indicate retinal changes in early diabetic retinopathy in the same manner as the OPs.  相似文献   

2.
ERG findings in five sisters are reported. By pedigree analysis, four of the five must be obligate carriers for I-CSNB since their sons were affected (impaired night vision, reduced visual acuity, variable ametropia, congenital nystagmus and ERG with both scotopic and photopic b-wave reduced amplitude). The fifth was childless at the time of examination and her ERG analysis was normal. Three of the four obligate carriers showed significant reduction in the sum of the OPs amplitude as previously reported as being an electrophysiological signs in female carriers: two without alteration in other ERG components and the third with association with a flicker ERG amplitude significantly increased. The fourth female carrier showed a normal sum of the OPs amplitude whereas the other b-wave ERG or flicker amplitudes were significantly decreased. These last two ERG results suggest a possible modifications of synaptic transmission at a post-receptoral site (outer plexiform layer or involvement of the bipolar pathways) in these two carriers.  相似文献   

3.
The purpose of this study was to determine the ability of electroretinographic (ERG) measurements to document progression of the retinopathy in a rat glaucoma model. Thirty four rats with a chronic intraocular pressure (IOP) elevation induced in one eye by cautery of three episcleral/extra-orbital veins were studied in four separate groups. ERGs were recorded sequentially in Group A rats (n = 12) at baseline, and after approximately 20, 40 and 60 days of high IOP, and in three additional groups of rats (n = 6 or 10 per group) after approximately 58, 30 and 175 days of high IOP, respectively. Scotopic ERG parameters recorded simultaneously from both eyes in Group A rats were: a- and b-wave amplitudes, implicit times, oscillatory potential amplitudes (OPs) determined at three different light-flash intensities, and the light-adapted (photopic) ERG b-wave amplitude. In the other groups of rats, only scotopic ERG a-wave, b-wave and OP amplitudes were measured.In Group A rats that were followed sequentially, all the ERG parameters recorded with attenuated stimuli showed significant time-dependent changes in glaucomatous eyes relative to their contralateral normal eyes, with OPs showing the earliest significant difference after only 3 weeks of high IOP. When different groups of unilateral glaucomatous rats were compared beyond 8 weeks of elevated IOP only the OPs showed a continued decrease with time and good discrimination between glaucoma and normal eyes. Over a 25 week period of high IOP the scotopic OPs measured with attenuated light stimuli declined at the rate of approximately 1.5% per week and provided the best ERG measure to monitor progression of retinal pathophysiology in the vein-occlusion rat glaucoma model.  相似文献   

4.
PURPOSE: To assess the inter-ocular and inter-session reliability for a range of parameters derived from the photopic electroretinogram (ERG) in a group of normal non-human primates. METHODS: Inter-ocular differences for photopic ERGs were assessed in a group of normal anesthetized adult rhesus monkeys (Macaca mulatta, n=29); inter-session reliability was assessed for 23 eyes of 23 animals tested 3 months later. Signals were acquired using Burian-Allen contact lens electrodes, whereby the contralateral cornea served as a reference. Photopic ERGs were elicited using red Ganzfeld flashes (-0.5-0.67 log photopic cd.sm(-2)) on a rod suppressing blue-background (30 scotopic cdm(-2)). Measurement reliability was established for a-wave, b-wave, photopic negative response (PhNR) and oscillatory potential (OP) amplitudes, as well as for their implicit times, by calculation of the 95% limits-of-agreement (LOA) and the coefficient-of-variation (COV) for each parameter. RESULTS: OP and a-wave amplitudes increased with intensity up to 0.67 log photopic cd.sm(-2), following a typical saturating function, whereas b-wave and PhNR amplitudes both declined above 0.42 log photopic cd.sm(-2). Inter-session variability was greater than inter-ocular variability. The inter-session COVs for PhNR amplitude (10-20%) were similar to the other photopic ERG components (a-wave: 12-17%, b-wave: 12-17%, OPs: 13-19%). Inter-session LOAs were also similar across components, but on average, were smallest for responses to moderate intensities (0.0-0.42 log photopic cd.sm(-2)). CONCLUSION: In non-human primates, the 95% LOA for inter-session measurements of the photopic ERG a-wave, b-wave, OPs and PhNR are all similar. Inner-retinal damage may best be measured using the PhNR amplitude for moderately bright stimulus intensities. B-wave and PhNR amplitudes for brighter flashes are smaller and more variable. The ratio of PhNR:b-wave amplitudes manifests smaller variability and may therefore be useful for detection of selective PhNR loss.  相似文献   

5.
A patient with congenital stationary night blindness (CSNB) (Schubert-Bornschein type) transmitted as an autosomal recessive trait was studied with several tests of electrical function as well as a variety of psychophysical procedures. Comparison of the patient's present findings with those obtained 23 years earlier showed that while rod thresholds have remained the same, cone sensitivity has decreased. Subjective flicker thresholds obtained following a bleach were unchanged during the course of dark adaptation. The absence of rod-cone interaction, together with an absent scotopic b-wave, implies that the defect is in the mid-retinal layers. Further, the absence of oscillatory potentials in the photopic electroretinogram (ERG) suggests that the interplexiform cell may be implicated in some manner. The focal ERG of the CSNB patient showed normal amplitude and normal phase delays, supporting the idea that the focal ERG samples primarily cone photoreceptor activity.  相似文献   

6.
Scotopic and photopic electroretinograms (ERGs) were recorded in 12 healthy volunteers before and 90 and 180 min after administration of levodopa. After 90 min the drug significantly increased the scotopic ERG b-wave amplitude and implicit time. The dark-adapted oscillatory potentials (OPs) were selectively affected, while no changes were observed in the photopic ERG. Levodopa had no effect on the ERG after 180 min drug applications. As a control, the experimental procedure was repeated without drug administration, and no changes were observed.  相似文献   

7.
目的:评价视网膜脱离患者年龄、病程、视网膜脱离面积、黄斑脱离情况等因素对视网膜功能的影响。方法:将孔源性视网膜脱离(retinal detachment,RD)188例189眼的患者年龄、病程、视网膜脱离面积、黄斑脱离情况、视力与视网膜脱离眼的fERG和mfERG各指标进行相关分析。结果:影响RD眼fERG和mfERG的主要因素是脱离面积、黄斑脱离和视力。以|γ|>0.4,且P≤0.05判定为有相关性。脱离面积与明视和暗适应最大反应ERG a、b波幅值,30Hz闪烁光幅值,OPs波数和幅值负相关;与mfERG象限野P1波幅值密度、幅值负相关。相关系数最高者为fERG暗适应最大反应b波幅值(γ=-0.704)。黄斑脱离与明视和暗适应最大反应ERG b波幅值,30Hz闪烁光ERG幅值负相关;与mfERG环形野环1的P1波幅值密度、幅值负相关,与mfERG象限野P1波幅值密度负相关,相关系数最高者为mfERG环形野环1的P1波幅值(γ=-0.584)。视力与明视和暗适应最大反应a、b波幅值,30Hz闪烁光幅值,OPs子波数和幅值正相关;与mfERG环形野环1的P1波幅值密度、幅值正相关,相关系数最高者为30Hz闪烁光ERG幅值(γ=0.597)。RD眼的fERG异常率最高者为暗适应最大反应ERG b波幅值,异常率为71.3%,视网膜脱离象限野mfERG异常率最高者为P1波幅值,异常率为85.3%。结论:影响RD患者视网膜功能的重要因素是脱离面积和黄斑脱离情况。RD眼对视网膜功能异常反应的mfERG对视网膜功能异常反应的敏感性高于fERG。  相似文献   

8.

Purpose

We have monitored retinal function in patients treated for retinoblastoma (primarily, but not exclusively by intra-arterial chemotherapy infusion) by electroretinography (ERG) recordings for the past 7 years. We here present data from 599 ERG studies of 108 patients, in which a complete ERG protocol including both photopic and scotopic recordings was performed, in justification of our frequent practice of reporting primarily 30-Hz photopic flicker amplitude data.

Methods

Patients referred for treatment of retinoblastoma underwent ERG recordings during examination under anesthesia whenever possible: at baseline and following most treatment sessions. Correlations were calculated for the complete datasets between the four primary amplitude response parameters: photopic single flash b-wave, photopic 30-Hz flicker peak-to-trough, scotopic rod-isolating b-wave, and scotopic maximal flash b-wave.

Results

Using our adaptation of the International Society for Clinical Electrophysiology of Vision-recommended standard ERG protocol, ERG responses of eyes of patients with untreated retinoblastoma or following traditional or intra-arterial treatment for retinoblastoma show very high correlations between 30-Hz flicker amplitude responses and three other standard photopic and scotopic ERG response amplitudes. Reductions in ERG amplitudes seen in these eyes following treatment show no significant difference between retinal dysfunction estimated using rod- or cone-dominated responses.

Conclusion

These observations support the use of photopic response amplitudes (especially in response to 30-Hz flicker) as the primary ERG outcome measure in studies of treated and untreated eyes with retinoblastoma when more complete ERG protocols may be impractical.  相似文献   

9.
Electroretinogram in cone dystrophy.   总被引:1,自引:0,他引:1  
Electroretinograms (ERGs) in 10 cases of cone dystrophy were studied with special respect to log(bp/bs) that represents the log of photopic ERG amplitude divided by scotopic ERG amplitude. Photopic ERGs were either greatly diminished or nonrecordable, and scotopic ERGs showed either normal or reduced amplitudes. All cases had a low value of log(bp/bs), less than the lower normal limit, indicating significantly greater impairment in cone function than in rod function. These results have proved log(bp/bs) to be helpful in confirming the diagnosis of cone dystrophy especially in cases with recordable photopic ERG and reduced scotopic ERG. Among other ERG parameters, the photopic ERG b-wave implicit time that was determined with averaging and digital amplification of the responses in 4 cases showed prolongation in 3 cases while normal in one case. Oscillatory potentials were nonrecordable or barely recordable in all cases.  相似文献   

10.
Three patients with a bull's-eye macular lesion and other signs characteristic of cone dystrophy gave an unusual ERG finding. In response to a white flash of moderate intensity the scotopic b-wave amplitude was considerably larger than normal. One patient had elevated rod thresholds and nyctalopia, while the other 2 had normal rod sensitivity associated with the supernormal scotopic b-wave amplitude. In the latter 2 patients the abnormal ERG pattern was unchanged for 4 years and 7 years respectively. This atypical finding, of a supernormal scotopic b-wave amplitude in response to light of moderate intensity, appears to characterise a subgroup of patients with cone dystrophy, probably of autosomal recessive inheritance. The pathogenesis of the abnormal ERG remains uncertain.  相似文献   

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