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PubMed1978

An improved electrode for electroretinography: design and standardization.

An electrode for electroretinography was developed that fits over the patient's lower lid. The electrode incorporates a platinum strip embedded in a piece of shaped plexiglass. The electrode was standardized for clinical use by comparing ERG recordings from this platinum lid electrode with those recorded from a Burian-Allen electrode. The a- and b-wave implicit times and amplitudes were measured in four subjects, using both electrodes under varying luminance conditions, to provide a measure of the validity of the platinum lid electrode. The same experimental procedure was repeated five times on two individuals to provide a measure of the reliability of both electrodes. Results indicate amplitudes approximately 65% of those recorded with a Burian-Allen electrode but which are otherwise in good agreement.

Electrodes↗

PubMedDate not supplied

Basic principles of clinical electroretinography.

Before applying the technique of electroretinography to the investigation of retinal disorders, it is imperative to understand the cells within the retina that generate its component waveforms and the manner in which various stimuli and background conditions modify their amplitude and isolate cone and rod contributions.

Dark Adaptation↗

PubMed2003

Multifocal electroretinography evaluation for early detection of retinal dysfunction in patients taking hydroxychloroquine.

PURPOSE: To evaluate macular function using multifocal electroretinography (mfERG) in a cohort of asymptomatic patients taking hydroxychloroquine and a patient with maculopathy secondary to hydroxychloroquine treatment. METHODS: mfERG recordings were obtained for both eyes of 11 patients taking hydroxychloroquine without clinical signs of toxicity and 1 patient with toxic maculopathy. Initially, the classic m-sequence paradigm for the first-order kernel (103 hexagons; 2.7 candela x seconds/m2 peak luminance) was recorded. After that, another special stimulation mode was applied, which emphasized second-order adaptational effects (modulated multifocal flashes with interleaved global flashes, MF0F0 paradigm). RESULTS: The patient with toxic maculopathy and one patient without toxicity had multiple areas of decreased retinal responses bilaterally (classic m-sequence). The patient with toxicity and another three patients without toxicity presented with multiple areas of decreased retinal function in both eyes with the second-order component of the MF0F0 paradigm. Repeated recordings of 1 patient 8 months after the initial recording demonstrated evidence for reproducibility of the second-order adaptive effects. CONCLUSION: Clinically asymptomatic patients receiving hydroxychloroquine treatment can have substantial local decreases in their retinal function, as reflected by the changes in mfERG recordings, possibly indicating a preclinical stage of drug-related toxicity.

Adult↗

PubMed2006

Multifocal electroretinography and fluorescein angiography in retinal vein occlusion.

PURPOSE: To interpret the responses of multifocal electroretinography (mfERG) of the central macula in retinal vein occlusion and correlate them with findings of fluorescein angiography, optical coherence tomography (OCT), and visual acuity. METHODS: In a prospective observational case series, 25 patients with branch or hemiretinal vein occlusion were examined by means of mfERG, fluorescein angiography, OCT, and visual acuity. RESULTS: In eyes with macular ischemia shown by fluorescein angiography, the implicit time was significantly longer than that in eyes without macular ischemia (P = 0.006; Mann-Whitney test). The amplitudes in the first-order kernel responses in the ischemic eyes were more reduced (P = 0.04; Mann-Whitney test), and the amplitudes in the central macula correlated well with visual acuity (P = 0.006; Pearson correlation). There was no significant correlation between the degree of retinal thickening as measured by OCT and the mfERG responses, although there was a trend toward reduced amplitudes in the maculae with central retinal thickening (P = 0.08; Pearson correlation). CONCLUSION: Macular ischemia as measured by fluorescein angiography correlates well with the prolonged implicit time on the first-order kernel response in mfERG, but no significant correlation was detected between the responses of mfERG and the OCT findings. Further investigations will demonstrate if this can be used as a prognostic instrument in the selection of patients, who will most likely benefit from future treatments.

Adult↗

PubMed2007

Retinal function after scleral buckling for recent onset rhegmatogenous retinal detachment: assessment with electroretinography and optical coherence tomography.

PURPOSE: To investigate central and peripheral retinal function after scleral buckling surgery for recent onset rhegmatogenous retinal detachment (RD). METHODS: Fifteen phakic patients with rhegmatogenous RD for <1 week underwent scleral buckling surgery. Clinical investigation, optical coherence tomography (OCT), full-field electroretinography (ERG), and multifocal ERG (mfERG) with fundus illumination were performed preoperatively and 6 months postoperatively. RESULTS: Anatomical success was achieved in 14 patients. mfERG amplitudes were reduced preoperatively in detached retina, with significant improvement at follow-up (P = 0.002). Foveal amplitudes improved significantly (P = 0.027). There was no significant difference in postoperative mfERG amplitudes between areas that had been preoperatively detached or attached (P = 0.739). In the subgroup of eight patients in whom the detachment engaged the fovea preoperatively, rod function improved significantly as assessed with full-field ERG (P = 0.008). In these patients, the extent of detachment ranged between 4 clock hours and 6 clock hours, as compared with 2 clock hours and 5 clock hours in the remaining patients. OCT showed subretinal foveal fluid in four patients at follow-up. CONCLUSIONS: In recent onset rhegmatogenous RD, total rod and localized central retinal dysfunction in detached retina can improve significantly after reattachment. mfERG and OCT are suitable tools for further studies of functional outcomes in RD.

Adult↗

PubMedDate not supplied

Detection of cone dysfunction induced by digoxin in dogs by multicolor electroretinography.

It is difficult to detect discrete cone function with the present conventional electroretinography (ERG) examination. In this study, we developed contact electrodes with a built-in color (red (644 nm), green (525 nm), or blue (470 nm)) light source (color LED-electrode), and evaluated an experimental model of digoxin in the dog. First, 17 normal Beagle dogs were used to determine which electrode works well for color ERG measurement on dogs. Then, color ERG was performed on seven normal Beagle dogs at various points during a 14-day period of digoxin administration. A single daily dose of 0.0125 mg/kg/day, which is within the recommended oral maintenance dosage range for dogs, was administered orally for 2 weeks. Ophthalmic examination, measurement of plasma concentration of digoxin, and color ERG examination were performed. On first examination, amplitudes of all responses were significantly (P < 0.01) lower with the red, than with the blue and green electrodes during ERG recording. In ERG using the red electrode, the standard deviation was large. According to these preliminary results, the red electrode was not used in the experimental dog model with digoxin. In the digoxin administrated animals, no significant change was observed in the ophthalmic examination findings. The digoxin level increased steadily throughout the dosing period but was always within the therapeutic range for dogs. In rod ERG, no abnormalities were detected with any electrode. In standard combined ERG, decreased amplitude of the a-wave was detected with every electrode. In single flash cone ERG, prolongation of implicit time was detected by color ERG with the blue and green electrodes. In 30-Hz flicker ERG, decreased amplitude was detected only by color ERG with the blue electrode. The decreased amplitude and prolonged implicit time recovered after termination of digoxin administration. Cone dysfunction induced by digoxin in the dog was revealed by multicolor ERG using blue and green LED-electrodes. Multi-color ERG was useful for detecting cone type-specific dysfunction in the dog.

Administration, Oral↗

PubMed2005

Multifocal electroretinography in isolated arterially perfused bovine eye.

AIM: To develop an isolated arterially perfused bovine eye as an in vitro model for studying retinal electrophysiology using multifocal electroretinography (mfERG). METHODS: Fresh bovine eyes were cannulated through the ophthalmic artery and perfused with oxygenated Krebs' solution at 37 degrees C within 15 min postmortem. Multifocal ERG was recorded using the veris 1.0 (Visual Evoked Response Imaging System). RESULTS: The mfERG waveform of in vitro bovine eyes had a typical trough (negative wave, N1) and peak (positive wave, P1) similar to those of human mfERG. The implicit times (peak latencies) for N1 and P1 were 20 and 42 ms respectively, and the average response amplitude (N1P1) was 55 nV. The implicit times of N1 and P1 were maintained for more than 4 h. The mfERG responses were affected proportionately by the stimulus intensity. Without a neutral density filter, the mean response amplitude was about 55 nV, which was diminished to 26, 18 and 10 nV under neutral density filters of 0.4, 1.0 and 1.4, respectively. Partial occlusion of the pupil completely abolished mfERG responses from the corresponding part of the retina. CONCLUSIONS: Isolated arterially perfused bovine eye may be used as an experimental model to study retinal electrophysiology using mfERG. The in vitro eye may offer a convenient and easily obtainable alternative to live animals, particularly for drug screening and invasive studies.

Animals↗

PubMed1997

Electroretinography of central retinal vein occlusion under scotopic and photopic conditions: what to measure?

INTRODUCTION: In the management of cases of central retinal vein occlusion it is important to identify those patients who will develop the complication of iris neovascularisation. Electroretinography is of proven use in this role but there is some confusion about which parameters to measure and at what stimulus intensities. METHODS: A variety of ERG parameters in scotopic and photopic conditions were tested by ROC analysis for the prediction of the development of this complication in 39 patients with CRVO. RESULTS: The results indicated that a single flash and measurement of the b/a ratio under photopic conditions is as effective in this aim as measuring multiple parameters. CONCLUSION: A simplified and shortened protocol could be used in the examination of this condition thereby making the application of ERG more practical in the clinical setting.

Adaptation, Ocular↗

PubMed2004

Multifocal electroretinography and optical coherence tomography in two patients with solar retinopathy.

PURPOSE: Clinical investigation of central retinal dysfunction in two cases of solar retinopathy. METHODS: Two patients were examined for best corrected visual acuity (VA), fundus inspection, visual fields, multifocal electroretinography (mfERG) with a stimulus pattern of 241 hexagons and, at follow-up, also with optical coherence tomography (OCT). RESULTS: At the initial examination, mfERG revealed central retinal dysfunction, which had improved by the time of follow-up. In Case 1, a foveal oedema regressed over time, although VA remained slightly reduced. In Case 2, OCT showed spots of increased reflectivity corresponding to the patient's symptoms. CONCLUSION: Central retinal dysfunction due to solar retinopathy may improve over time. However, structural and functional changes may persist. This report illustrates that mfERG and OCT are useful tools for objective documentation of the pathology in solar retinopathy.

Adult↗

PubMed2006

Retinal function following transpupillary thermotherapy for occult choroidal neovascularization in age-related macular degeneration: a short-term study by focal electroretinography.

PURPOSE: To assess short-term changes in macular function after transpupillary thermotherapy (TTT) in patients with occult subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD), using focal electroretinography (FERG). METHODS: Twenty-five patients with occult subfoveal CNV due to AMD were treated with TTT delivered using an infrared (810 nm) diode laser (spot size 3.0 mm, laser power 400-600 mW, duration 60 seconds). All patients were clinically evaluated before, 1 and 6 weeks after treatment. Snellen visual acuity (VA) was measured at each visit. Fluorescein angiography (FA) was performed at baseline and 6 weeks after TTT. Focal ERGs were recorded in all patients immediately before and 1 week after TTT in response to an 18-degree diameter, 41 Hz flickering spot (630 nm) centred on the fovea, presented on a steady background in Maxwellian view. A subgroup of 12 patients was also re-tested by FERG at 6-weeks post-TTT. RESULTS: No significant changes in mean FERG amplitude and phase were observed across the different recording sessions before and after TTT. One week after TTT, four patients had significant (> 2 SD from baseline variability) increases in FERG amplitude and/or phase advances, one had a decrease in amplitude and four had phase delays, compared to baseline. The remaining 15 patients had stable FERGs. Six weeks after TTT, four patients had significant increases in FERG amplitude and/or phase advances, four had decreases in amplitude and/or phase delays, and four had stable FERGs, compared to baseline. Improvement in FERG parameters after TTT was always associated with an improvement in VA and a decrease in exudation. Patients with post-TTT FERG deterioration had stable or deteriorated clinical pictures. At either 1 or 6 weeks post-TTT, the FERG amplitude increase was inversely correlated (p < 0.05) with the baseline FERG amplitude and VA. CONCLUSIONS: Three major conclusions can be drawn: in a short-term follow-up, TTT was not found to be associated with significant changes in macular function; FERG improvement was associated with VA improvement, and the increase in FERG amplitude was greatest in patients with the worst baseline acuity.

Aged↗

PubMed1980

Electroretinography by skin electrodes and signal averaging method.

In the investigation of suspected visual disorders, ERG is of considerable value. A simplified method for clinical electroretinography by non-corneal electrodes is presented. The latency and amplitude values were measured in 22 normal subjects. Using skin electrodes and signal averaging, we can record, without discomfort to the patient, an electroretinogram with a waveform and time relations similar to those obtained by corneal electrodes. Non-corneal ERG is useful for infants, children as well as sensitive adult patients, and is also applicable after recent eye surgery and in cases of infection or injury of the anterior segment. Since non-corneal electrodes do not obstruct the stimulus light or cause of refractive change, they are advantageous when ERG is recorded simultaneously with visually evoked cortical response (VER). When it is important to stimulate only one eye at a time in flash VER, the adequacy of the cover is verified by the absence of an ERG from the covered eye.

Adult↗

PubMed1995

Comparison of colour discrimination and electroretinography in evaluation of visual pathway dysfunction in aretinopathic IDDM patients.

The slow progression of diabetic retinopathy makes it difficult to assess the effects of intervention therapy. There is thus a need for surrogate markers of visual change in diabetes. Colour vision tests and electroretinography (ERG) may be useful in this regard; yet little is known of their relative performance in the assessment of visual dysfunction in diabetes. The aim of the present study was to compare colour discrimination (100 hue test) and ERG indices (oscillatory potentials (OP) and pattern ERG (PERG)) in the evaluation of aretinopathic IDDM patients. Colour discrimination was abnormal in 10 aretinopathic IDDM patients when compared with nine age matched controls; mean square root 100 hue error scores were 10.38 (SD 2.89) versus 4.77 (1.87) respectively, p < 0.01. OP implicit times of the ERG were also abnormal; for example, for right eye, mean OP1 implicit time for diabetics versus OP1 implicit time for controls was 20.1 (2.0) versus 18.6 (1.4) ms, p = 0.03. Comparison of the two techniques suggested that the 100 hue test was more sensitive and more specific than ERG OP implicit times in the detection of diabetic visual dysfunction in these patients.

Adult↗

PubMed1989

Pattern electroretinography in patients with delayed pattern visual evoked potentials due to distal anterior visual pathway dysfunction.

Between March 1983 and January 1988 delayed pattern visual evoked potentials (PVEP) were observed in 67 patients with distal visual pathway dysfunction. Many of these patients had been referred for neurophysiological examination because of possible optic nerve dysfunction. These patients also had pattern electroretinography (PERG) performed which in all cases showed an abnormality of the main positive P50 component. None of these patients had an abnormality confined to the negative N95 component, the type of abnormality usually found if the PERG is abnormal in optic nerve disease. It is suggested that PERG recording should now be a routine adjunct to the PVEP in the assessment of anterior visual pathway dysfunction.

Adolescent↗

PubMedDate not supplied

Multifocal electroretinography changes in the macula at high altitude: a report of three cases.

BACKGROUND: To evaluate the short- and long-term effects of high-altitude hypobaric hypoxia on macula morphology and function during ascents, acclimatizations, and descents between 500 m and 5,650 m, macula function was evaluated in three healthy climbers of a trekking expedition. METHODS: Macula physiology was tested with multifocal electroretinography (MF ERG), near and farvisual acuity, and Amsler grid tests. Macula morphology was tested with optical coherence tomography (OCT) and with stereoscopic fundoscopy obtained 1 week before ascent, as well as 1 week and 2 weeks after high-altitude exposure. The following physiological parameters indicative of acclimatization were compared daily during the expedition at altitudes between 500 m and 5,050 m: hemoglobin, oxygen saturation, resting heart rate, retinal findings, and the Lake Louise score of acclimatization. RESULTS: The central macula MF ERG responses were significantly reduced 1 week after high-altitude exposure, and had recovered by the follow-up examination performed during the following week. Near visual acuity and Amsler grid tests remained unaffected at both follow-up examinations. No significant changes were found in the follow-up OCT and daily fundoscopy examinations in all three well-acclimatized climbers. CONCLUSIONS: High-altitude hypobaric hypoxia affects the function of the highly sensitive macula region. This suggests that the exposure of persons with macula diseases such as age-related macula degeneration, tapetoretinal degeneration, or diabetic retinopathy to high altitudes may influence the disease progression. For this reason, this population should avoid prolonged and unnecessary high-altitude exposure without proper acclimatization.

Acclimatization↗

PubMed1989

Vitrectomy for diabetic eye disease. The prognostic value of pre-operative electroretinography and visual evoked cortical potentials.

An investigation was carried out into the prognostic value of standard flash electroretinography (ERG) and visual-evoked cortical potentials (VECP) recorded for 87 diabetic eyes prior to vitrectomy. 95% of the eyes with a recordable ERG b-wave achieved a post-operative visual acuity (VA) of 0.05 or better (positive predictive value), but only 35% of the eyes with a good post-operative VA had a recordable b-wave (sensitivity). The corresponding values for the ERG a-wave were 67 and 72%, and for the VECP 77 and 69%, respectively. A non-recordable b-wave in the ERG was associated with a poor visual outcome (VA less than 0.05) in 45% of cases (negative predictive value), and 97% of the eyes with a poor visual outcome had a nonrecordable b-wave (specificity). The corresponding values for the ERG a-wave were 42 and 37%, and for the VECP 53 and 63%, respectively. Consequently, the odds ratio for an unfavourable visual outcome (VA less than 0.05) was greater for a non-recordable b-wave (15.7) than for a nonrecordable VECP (3.8) or a non-recordable a-wave (1.5). Recordability of the b-wave gave the best prediction for attached macula. Extensive photocoagulation diminished all ERG and VECP amplitudes. Vitreous opacities had no significant effect on the ERG or VECP.

Adolescent↗

PubMed1978

Possible indication of dopaminergic blockade in man by electroretinography.

In view of the finding that dopamine is the principle neurotransmitter in the retina, an attempt was made to demonstrate dopaminergic receptor blockade by means of electroretinography. In an open experimental setting, the effect of 50 mg thioridazine was compared with that of placebo in 2 groups of 10 normal volunteers. In the placebo group, the post-drug scotopic electroretinogram (ERG) was not significantly different from the pre-drug ERG, while in the thioridazine group, the post-drug scotopic ERG showed prolongation of 'a' wave latency time, prolongation of 'b' wave evolution time, and diminution of 'b' wave amplitude.

Action Potentials↗

PubMed2003

Cone selective adaptation influences L- and M-cone driven signals in electroretinography and psychophysics.

To assess the influence of selective adaptation of long (L) and middle (M) wavelength sensitive cones with electroretinography (ERG) and psychophysics, a novel adaptation procedure was developed, which comprises a selective and quantifiable change in the state of adaptation in the different cone types. One adaptation condition was used as a reference. In four additional conditions, the M-cones or the L-cones were selectively adapted, so that they absorbed either more or less photons. At each of these five states of adaptation, the ERG response amplitudes to 30Hz L- and to M-cone selective stimuli were measured. Furthermore, the psychophysical sensitivities to L- and M-cone selective stimuli were measured at different temporal frequencies. In subjects with normal color vision, adaptation can have a strong influence on the L- and M-cone driven response amplitudes in the ERG and on both the L- and the M-cone sensitivities in the psychophysical luminance channel. As a result, the L- to M-cone ERG and psychophysical ratios can change dramatically at the different states of adaptation. The cone sensitivity thresholds and the L- to M-cone sensitivity ratio in the psychophysical chromatic channel are about unity at all states of adaptation, suggesting the presence of a compensatory mechanism. In dichromats, the responses and sensitivities to stimulation of the absent cone type were generally small at all states of adaptation. But, with reddish backgrounds residual ERG responses and residual psychophysical sensitivities were observed, indicating the presence of either a robust rod driven signal or an additional adaptation mechanisms that are not cone driven and that have not been described before.

Adaptation, Ocular↗

PubMed2004

Electroretinography as a screening method for mutations causing retinal dysfunction in mice.

PURPOSE: To detect mice with hereditary retinal impairment, a high-throughput electroretinography (ERG) screening system was established. METHOD: Mice from eight different strains without known retinal disorders (102, 129/SvJ, AKR, C57BL/6J, C57BL/6JIco, CBA/CaJ, and DBA/2NCrlBR) and one control strain with retinal degeneration (C3HeB/FeJ) were fixed on a specially constructed sled, ERG electrodes were placed on the cornea, and mice were moved into a Ganzfeld stimulator. From a luminance range of 0.0125 to 500 cd-s/m(2) in a pretest series two levels (5 and 125 cd-s/m(2)) were chosen to shorten examination times. The root mean square (RMS) of the ERG-recording was analyzed to detect animals with abnormal retinal function. ERG responses of the left and right eyes were compared in amplitudes and implicit times of the a- and b-waves. Statistical analysis of the latter parameters was performed in all wild-type animals. Histology was performed on selected mice. RESULTS: ERG recordings of individual animals for the left and right eye revealed good agreement in amplitudes and implicit times of the a- and b-waves (P < 0.05). Comparison of these parameters among the wild-type strains showed several differences. Evaluation of the RMS revealed, in addition to the C3HeB/FeJ mice, a subgroup of mice within the 129/SvJ strain with abnormal retinal function. Molecular analysis of these mice demonstrated the presence of the same retroviral insertion in the Pde6b gene, which is causative of the Pde6b(rd1) allele carried in C3HeB/FeJ mice. Histologic analysis demonstrated good correlation between retinal electrophysiology and morphology. CONCLUSIONS: The present results demonstrate the feasibility of ERG for screening a large number of mice to detect animals with functional retinal impairment.

3',5'-Cyclic-GMP Phosphodiesterases↗