Flash electroretinography in standing horses using the DTL microfiber electrode (original) (raw)
Related papers
Vision Research, 2001
Different electrodes and stimulus protocols commonly used for electroretinography in rodent eyes were compared for convenience of use, degree of damage to corneal epithelium, and for magnitude of amplitude, reproducibility, left versus right eye accuracy, and reliability of recorded parameters of the flash electroretinogram (ERG). Adult C57BL/6 pigmented mice and albino Wistar rats were used to determine scotopic ERGs in response to Ganzfeld or strobe-light stimulation and light-adapted (photopic) ERGs recorded from both eyes at the same time. Test-retest data were used for statistical analyses to compare a monopolar gold-wire contact lens electrode (CLE), a cotton-wick silver-silver chloride electrode (CSCE), a DTL fiber electrode (DTLE), and a circular stainless steel wire electrode (SSE). Corneas were evaluated for abrasion after ERG recordings using fluorescein staining and also for the time taken, ease of insertion, and re-insertions required for the different electrodes. Compared to CSCE, DTLE, and SSE, the ERG potentials recorded by CLE had significantly larger scotopic amplitudes and oscillatory potentials under strobe or Ganzfeld stimulation and for light-adapted ERG b-wave amplitudes in both mice and rats. In analyzing test-retest data of scotopic ERG a-wave and b-wave amplitudes, the intraclass correlation coefficient showed the best agreement for the CLE (range 0.61-0.94) compared to the SSE (0.13-0.77), DTLE (0.02-0.69), and CSCE (0.12-0.51). In mice and rats, logistic regression analyses revealed significant correlations for amplitudes of most scotopic ERG parameters between contralateral eyes obtained with CLE and for some ERG components recorded by SSE. When comparing ERG amplitudes for stimulation by strobe or Ganzfeld, the difference was least with the CLE compared to DTLE, CSCE, or SSE. The time taken to insert the four different electrodes was greatest for the CLE in both mice and rats. The extent of corneal abrasion resulting from electrode use in mice was largest for the SSE followed by the CLE. However, in rats there was almost no corneal damage after ERG recordings with the CLE. Because of the stability of eye contact, the CLE allows ERGs to be determined over a longer recording session. Recording of scotopic and photopic (light-adapted) ERGs in rodents with monopolar gold-wire contact lens electrodes provides greater amplitudes and higher reproducibility when compared to other commonly used corneal electrodes. These electrodes are significantly better overall than others that were evaluated and should be considered for a standard protocol to monitor retinal function in rodent eyes.
Documenta ophthalmologica. Advances in ophthalmology, 1999
To compare corneal electrodes commonly used in rodent eyes for repeat and left versus right eye accuracy and variability to record the flash electroretinogram (ERG). Animals studied were eight C57BL/6 mice and eight rats of the Wistar strain. Scotopic ERGs were recorded from eyes of dark-adapted anesthetized rodents to compare a custom-made gold-wire contact lens electrode (CLE), a cotton-wick silver-silver chloride electrode (SCLE), and a coiled stainless steel wire electrode (SSE). Compared to SCLE and SSE. the potentials recorded by CLE are characterized by significantly larger ERG amplitudes and oscillatory potentials in both rats and mice (p <0.0001). In analyzing test-retest data comparing the three different electrodes the coefficient of variation was smaller (range, 10.3-15.5%) and the interclass correlation coefficient (0.77-0.93) showed a better agreement for the CLE. Recording scotopic ERGs with custom-made gold-wire contact lens electrodes records large amplitudes and...
Documenta Ophthalmologica, 2008
Objectives: To demonstrate the clinical feasibility of using surface electrodes for recording flash electroretinography (ERG), using the stimulation standards of the International Society for the Clinical Electrophysiology of Vision (ISCEV), without pupillary dilation. Methods: Eighteen physiologically normal volunteers were tested. Surface recording electrodes were placed over the middle third of the lower eyelid of each eye, and the reference electrode placed on the temple. The recording filters and method of stimulation for the standard flash cone, 30 Hz flicker, rod, standard combined and oscillatory responses were those recommended by the ISCEV. Four patients with a history of visual dysfunction were also examined. Results: The amplitudes of the responses were noted to have a high signal to noise ratio, allowing us to average only a few responses. The waveform configurations were almost identical to those published using other recording methods. Patients with retinitis pigmentosa and early onset retinal dystrophy had abnormal responses, whereas patients with Stargardt’s Syndrome and spasm of accommodation had responses within normal limits. Conclusions: This study has established the clinical feasibility of performing flash ERG using surface skin electrodes, with no pupillary dilation and using the stimulation standards of the ISCEV.
Test–retest reliability of scotopic full-field electroretinograms in rabbits
Documenta Ophthalmologica, 2017
Purpose To explore test-retest reliability of standard scotopic full-field ERG measurements in New Zealand White rabbits. The ERG is widely used for testing of retinal integrity after any ocular treatment. We here present detailed stimulus-response dependencies for single healthy and untreated animals, concentrating on test-retest reproducibility. Materials and methods Five New Zealand White rabbits (aged 8-10 weeks, weight about 2.0-2.5 kg) underwent binocular ERG measurements after intramuscular anesthesia and pharmaceutical pupillary dilatation at a baseline day and 10 days later. Eleven scotopic flash strengths (0.0001-10 cd s/m 2) were presented. Variability was quantified via the 95% limits of agreement (LOA). Results The a-waves displayed the typical monotonic sigmoid amplitude increase with flash strength, and the b-waves peaked at 0.01 cd s/m 2 , followed by a marked dip at 0.1-0.3 cd s/m 2. LOA of both waves went through a maximum in the dip region. LOA divided by mean amplitudes (relative LOA) was fairly flat over flash strength, around 20% beyond the dip. Intraindividual interocular variability was markedly lower, around 10%. Conclusions Scotopic ERG responses in rabbits display a region of high variability at 0.1-0.3 cd s/ m 2 ; beyond that region the amplitude-LOA is 20%, the interocular LOA being half that value. The use of intraindividual control eyes for testing any toxicity of ocular agents thus appears markedly more sensitive. As a rule of thumb, we found the relative 95% LOA as 33% between individuals, 20% across sessions and 10% between eyes.
Steady-state electroretinograms and pattern electroretinograms in pigs
Graefes Archive for Clinical and Experimental Ophthalmology, 2001
Background: Electroretinograms (ERG) or pattern-electroretinograms (PERG) could be valuable for the quantification of potential damage to the pig retina by experimental erbium:YAG laser treatment. We therefore performed a normative study of ERGs and PERGs in pigs. Methods: We recorded ERGs and PERGs under general anaesthesia in two experiments. In experiment 1 we examined eight eyes from six pigs of 20–25 kg body weight; in experiment 2 we examined four eyes from four pigs of 40–45 kg body weight. We used flash and checkerboard stimuli. In experiment 1, the stimulus parameters were mean luminance 48.3 cd/m2 for checkerboard stimuli, 96.6 cd/m2 for ERG, check sizes of 4°, 8°, and 16°, temporal frequencies were 16 Hz for ERG and 8 rev/s for PERG. Three measurements were repeated after two weeks. Stimulus parameters for experiment 2 were luminance 175 (350) cd/m2, check sizes 1.6°, 3.2°, 6.7°, and 16°, temporal frequencies 6.3 Hz for ERG and 8 rev/s for PERG. Recordings were subjected to Fourier analysis. Results: In experiment 1 the mean ERG amplitude was 1.02±0.89 µV with a coefficient of variation of 42% for repeat sessions. The mean PERG amplitudes were 0.53±0.25 µV for 16° checks, 0.36±0.21 µV for 8°, and 0.25±0.17 µV for 4°. The mean coefficient of variation between two measurements was 103% for 16° checks, 24% for 8°, and 116% for 4°. In experiment 2 the mean ERG amplitude was 9.72±3.96 µV. The mean PERG amplitudes were 0.77±0.50 µV for 16° checks, 0.09±0.16 µV for 6.7°, 0.07±0.13 µV for 3.2°, and 0.08±0.09 µV for 1.6°. Conclusions: It was possible to record ERGs and PERGs in pigs. However, the ERG amplitudes were small; PERG amplitudes were even smaller in both groups and cannot be reliably recorded. A problem for both ERG and PERG was the high intra-individual and interindividual variability. Therefore, only very extensive damage to the retina by vitrectomy or Er:YAG laser treatment might lead to a significant change in the ERG or PERG amplitudes.
Documenta Ophthalmologica, 2012
To refine methods of electroretinographical (ERG) recording for the analysis of low retinal potentials under scotopic conditions in advanced retinal degenerative diseases. Standard Ganzfeld ERG equipment (Diagnosys LLC, Cambridge, UK) was used in 27 healthy volunteers (mean age 28 ± SD 8.5 years) to define the stimulation protocol. The protocol was then applied in clinical routine and 992 recordings were obtained from patients (mean age 40.6 ± 18.3 years) over a period of 5 years. A blue stimulus with a flicker frequency of 9 Hz was specified under scotopic conditions to preferentially record roddriven responses. A range of stimulus strengths (0.0000012-6.32 scot. cd s/m 2 and 6-14 ms flash duration) was tested for maximal amplitudes and interference between rods and cones. Analysis of results was done by standard Fourier Transformation and assessment of signal-to-noise ratio. Optimized stimulus parameters were found to be a timeintegrated luminance of 0.012 scot. cd s/m 2 using a blue (470 nm) flash of 10 ms duration at a repetition frequency of 9 Hz. Characteristic stimulus strength versus amplitude curves and tests with stimuli of red or green wavelength suggest a predominant rod-system response. The 9 Hz response was found statistically distinguishable from noise in 38% of patients with otherwise non-recordable rod responses according to International Society for Clinical Electrophysiology of Vision standards. Thus, we believe this protocol can be used to record ERG potentials in patients with advanced retinal diseases and in the evaluation of potential treatments for these patients. The ease of implementation in clinical routine and of statistical evaluation providing an observer-independent evaluation may further facilitate its employment.
Clinical electrophysiology in veterinary ophthalmology-the past, present & future.
The aim of this review is to introduce the reader to the world of clinical veterinary electroretinography. An important indication for ERG recordings in the dog is the early diagnosis of progressive retinal atrophy, an inherited form of photoreceptor degeneration, analogous to retinitis pigmentosa in humans. In most of the 20 canine breeds in which the disease has been studied electrophysiologically, changes in the ERG appear long before the appearance of clinical signs. This early diagnosis is a vital tool in efforts to eradicate the disease through preventive breeding. Pre-operative screening of canine cataract patients is another common indication for electroretinography in the dog. The ERG is also used to diagnose inherited and nutritional photoreceptor degenerations in the cat, and retinal disorders in a number of other animal species. The abundance of animal species (and breeds) seen by the veterinary ophthalmologist lends additional importance to the problem of a harmonized ERG recording protocol. The European College of Veterinary Ophthalmologists has set up a special committee to formulate guidelines for such a protocol. International meetings and wetlabs are also being organized as part of an effort to improve the quality of electrophysiological diagnosis that veterinary ophthalmologists provide their patients.
The multifocal electroretinogram (mfERG) in the pig
Acta Ophthalmologica Scandinavica, 2007
Purpose: To establish a method allowing multifocal electroretinography (mfERG) recording with simultaneous fundus monitoring on anaesthetized pigs. In addition we characterize the peaks of the porcine mfERG trace, and compare the visual streak area with the optic nerve head, a known nonresponse area. Finally we illustrate the feasibility of the method by performing mfERG after an induced laser burn in the visual streak. Methods: Fifteen pigs underwent mfERG recordings at baseline, and after 1 and 6 weeks of observation. One pig was evaluated before and after retinal diode laser treatment in the visual streak. Results: The porcine mfERG trace appears similar to the human mfERG trace, and can be described by three peaks named N1, P1 and N2. Significantly faster implicit time was found in the visual streak regarding N1 (P < 0.001) than in areas outside the visual streak. Amplitudes of all three peaks were increased in the visual streak (P < 0.005). The laser-treated area was characterized by a response similar to what is found at the location of the optic nerve head. Conclusion: Porcine mfERG is similar in appearance to the human response and can be described by the same three peaks. Significantly higher amplitudes of all three peaks are found in the visual streak when compared to the optic nerve head and inferior retina. We have detected the functional deficit caused by a laser burn at the size of 3 · 3 mm.
Clinical electrophysiology in veterinary ophthalmology--the past, present and future
Documenta ophthalmologica. Advances in ophthalmology, 2002
The aim of this review is to introduce the reader to the world of clinical veterinary electroretinography. An important indication for ERG recordings in the dog is the early diagnosis of progressive retinal atrophy, an inherited form of photoreceptor degeneration, analogous to retinitis pigmentosa in humans. In most of the 20 canine breeds in which the disease has been studied electrophysiologically, changes in the ERG appear long before the appearance of clinical signs. This early diagnosis is a vital tool in efforts to eradicate the disease through preventive breeding. Pre-operative screening of canine cataract patients is another common indication for electroretinography in the dog. The ERG is also used to diagnose inherited and nutritional photoreceptor degenerations in the cat, and retinal disorders in a number of other animal species. The abundance of animal species (and breeds) seen by the veterinary ophthalmologist lends additional importance to the problem of a harmonized E...