Multi-centre variability of ISCEV standard ERGs in two normal adults

Hamilton, Ruth; Abdlseaed, Abdlsaed Al; Healey, J.; Neveu, MM; Brown, Lawrence W.; Keating, David; McBain, Vikki A.; Sculfor, David; Thompson, Dorothy

doi:10.1007/s10633-014-9471-9

Cited by 14 publications

(10 citation statements)

References 23 publications

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“…The reduction found in peak-to-peak amplitudes recorded with skin electrodes in our study is consistent with previous reports of reductions of 75% and 80% (9) , 43%-73% (10) , 50%-70% (11) , 50% (12) , 23%-62% (13) , and 42%-57% (14) . Our data showed reductions between 46% and 62% on the peak-to-peak amplitudes.…”

Section: Discussionsupporting

confidence: 93%

Full-field electroretinogram recorded with skin electrodes in normal adults

Salomão¹,

Pereira²,

Berezovsky³

2016

Arquivos Brasileiros De Oftalmologia

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Approved by the following research ethics committee: Universidade Federal de São Paulo UNIFESP (#0174/04). ABSTRACT Purpose:Alternative recording methods have been tested to allow the electroretinogram (ERG) recording in uncooperative patients and/or patients with palpebral alterations, including recordings with skin electrodes. The purpose of this study was to compare ERG recorded with skin electrodes and well-established microfiber electrodes and to determine normative values of ERG parameters for recording with skin electrodes. Methods: Fifty healthy volunteers (17-26 years; mean 20.63 ± 2.01 years) participated in the study. A gold disk skin electrode was placed on the lower orbital rim of a randomly chosen eye. On the contralateral eye, a microfiber electrode was positioned in the lower conjunctival sac. Gold disc electrodes were positioned at the ipsilateral outer canthus of both eyes acting as reference electrodes for the creation of a potential difference. Two ground electrodes were placed on the lobe of each ear. ERGs were recorded according to the International Society of Clinical Electrophysiology Visual (ISCEV) protocol using the VERIS 5.1.9 system for data acquisition and analysis. Results: Both types of electrodes showed similar wave response morphologies. The implicit time of responses between the two electrodes was comparable. On peak-to-peak amplitude, skin electrode recordings showed an amplitude reduction of 61.4% for rod responses, 61.5% for maximal responses, 46.2% for oscillatory potentials, 57.4% for cone responses, and 54.4% for 30Hz-flicker responses, when compared with microfiber electrode recordings. Based on these findings, normative values for peak-to-peak amplitude and implicit time to be used as a reference for ERGs recorded with skin electrodes were determined. Conclusions: ERGs recorded with skin electrodes presented lower peak-to-peak amplitude compared with microfiber electrodes. However, using appropriate normative values, skin electrodes may be useful for specific target populations such as uncooperative infants and/or patients with ocular surface alterations.

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Section: Discussionsupporting

confidence: 93%

Full-field electroretinogram recorded with skin electrodes in normal adults

Salomão¹,

Pereira²,

Berezovsky³

2016

Arquivos Brasileiros De Oftalmologia

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“…Furthermore, the implicit times decrease with increasing stimulus strength. The absolute values of the scotopic a-and b-wave amplitudes measured with 3 cd·s m −2 flashes agree with those measured in humans at the same conditions (Hamilton et al, 2015). The implicit time of the a-wave at the same flash strength was also similar to those measured in human subjects.…”

Section: Feasibility Study 321 Ergssupporting

confidence: 86%

“…The implicit time of the a-wave at the same flash strength was also similar to those measured in human subjects. The latency of the b-wave was, however, shorter (35 ms) than those measured by Hamilton et al (2015) in human subjects (about 50 ms). In general, the responses to the different flash intensities are comparable to those measured in cynomolgus monkeys (Table 2).…”

Section: Feasibility Study 321 Ergscontrasting

confidence: 56%

Feasibility of intravitreal injections and ophthalmic safety assessment in marmoset (Callithrix jacchus) monkeys

et al. 2017

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Abstract. To safeguard patients, regulatory authorities require that new drugs that are to be given by the intravitreal (IVT) route are assessed for their safety in a laboratory species using the same route of administration. Due to the high similarity of ocular morphology and physiology between humans and nonhuman primates (NHPs) and due to the species specificity of many biotherapeutics, the monkey is often the only appropriate model. To this end, intravitreal administration and assessment of ocular toxicity are well established in cynomolgus monkeys (Macaca fascicularis). In contrast, the common marmoset monkey (Callithrix jacchus) is not a standard model for ocular toxicity studies due to its general sensitivity to laboratory investigations and small eye size. It was the purpose of the present work to study whether the marmoset is a useful alternative to the cynomolgus monkey for use in intravitreal toxicological studies. Six marmoset monkeys received repeated (every 2 weeks for a total of four doses) intravitreal injections of 10 or 20 µL of a placebo. The animals were assessed for measurements of intraocular pressure (IOP), standard ophthalmological investigations and electroretinography (ERG). At the end of the dosing period, the animals were sacrificed and the eyes were evaluated histologically. ERG revealed similar results when comparing predose to end-of-study data, and there was no difference between the two dose volumes. A transient increase in the IOP was seen immediately after dosing, which was more pronounced after dosing of 20 µL compared to 10 µL. Ophthalmologic and microscopic observations did not show any significant changes. Therefore, it can be concluded that 10 µL as well as 20 µL intravitreal injections of a placebo are well tolerated in the marmoset. These results demonstrate that the common marmoset is an alternative to the cynomolgus monkey for intravitreal toxicity testing.

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“…Estimates of heritability tended to be higher for response amplitudes than for implicit times, with almost all amplitudes having a lower limit of the 95% confidence interval for heritability that exceeded 50%. This is intriguing because implicit times tend to show less intersession and interlaboratory variability than response amplitudes, 23 suggesting that measurement error would be greater in amplitude quantification rather than implicit time. Measurement errors act as individual (i.e., unique) environmental factors in twin studies, and so would reduce estimates of heritability.…”

Section: Discussionmentioning

confidence: 99%

Relative Genetic and Environmental Contributions to Variations in Human Retinal Electrical Responses Quantified in a Twin Study

et al. 2017

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PurposeTo estimate heritability of parameters of human retinal electrophysiology and to explore which parameters change with age.DesignProspective, classic twin study.ParticipantsAdult monozygotic and dizygotic twin pairs recruited from the TwinsUK cohort.MethodsElectroretinogram responses were recorded using conductive fiber electrodes in response to stimuli incorporating standards set by the International Society for the Clinical Electrophysiology of Vision. These parameters were extracted; in addition, photopic negative-response (PhNR; originating from retinal ganglion cells) and i-wave components were extracted from responses to the photopic single flash. Parameter values were averaged from both eyes.Main Outcome MeasuresMean values were calculated for the cohort. Correlation coefficients with age were calculated (averaging parameters from both twins from each pair). Coefficients of intrapair correlation were calculated for monozygotic and dizygotic twins. Age-adjusted heritability estimates were derived using standard maximum likelihood structural equation twin modeling.ResultsResponses were recorded from 210 participants in total (59 monozygotic and 46 dizygotic twin pairs). Ninety-three percent were women. Mean age for the cohort was 62.4 years (standard deviation, 11.4 years). In general, response amplitudes correlated negatively, and implicit times positively, with age. Correlations were statistically significant (P < 0.05) and moderate or strong (coefficient, >0.35) for the following parameters: scotopic standard and bright-flash a-wave implicit times, photopic 30-Hz flicker and single-flash b-wave implicit times, and PhNR and i-wave implicit times. Intrapair correlations were higher for monozygotic than dizygotic twins, suggesting important genetic influences. Age-adjusted estimates of heritability were significant for all parameters (except scotopic dim-flash b-wave implicit time), ranging from 0.34 to 0.85. Highest estimates were for photopic single-flash a-wave and b-wave amplitudes (0.84 and 0.85, respectively).ConclusionsThis study explored heritability of retinal electrophysiologic parameters and included measurements reflecting ganglion cell function. Most parameters showed significant heritability, indicating that genetic factors are important, determining up to 85% of the variance in some cone system response parameters. Scotopic responses tended to show lower heritability (possibly relating to greater rod system susceptibility to environmental factors). Future studies can explore the identity of these genetic factors, improving our understanding of how they shape retinal function.

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Multi-centre variability of ISCEV standard ERGs in two normal adults

Cited by 14 publications

References 23 publications

Full-field electroretinogram recorded with skin electrodes in normal adults

Full-field electroretinogram recorded with skin electrodes in normal adults

Feasibility of intravitreal injections and ophthalmic safety assessment in marmoset (Callithrix jacchus) monkeys

Relative Genetic and Environmental Contributions to Variations in Human Retinal Electrical Responses Quantified in a Twin Study

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