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Home / Equine Research Bank / BMC Vet Res / Variability, repeatability and test-retest reliability of eq...
BMC veterinary research2020; 16(1); 261; doi: 10.1186/s12917-020-02463-8

Variability, repeatability and test-retest reliability of equine flash visual evoked potentials (FVEPs).

Abstract: Visual evoked potentials (VEPs) are electrical potentials generated by neurons in the central nervous system in response to visual stimuli. A series of positive and negative wavelets in response to flash-stimuli (flash-VEP; FVEP) or reversing, iso-luminant patterns (pattern-VEP; PVEP) are recorded. Pathological conditions affecting the post-retinal pathways can alter overall waveform morphology, and also affect wavelet peak times and amplitudes. FVEPs have recently been described in horses, but more data on the variability within and between subjects is required, to adequately interpret results from clinical equine patients. Therefore, the purpose of this study was to describe the variability, repeatability and test-retest reliability of equine FVEPs in normal, adult horses. Results: Equine FVEPs were recorded from one randomly selected eye in 17 horses, from both eyes in eight of these horses, and also at two separate recording sessions in six horses. N1, P2, N2 and P4 wavelets were present in 100% of the recordings in all horses, while P1, N2a, P3 and P5 were only present in some recordings. Coefficients of variation (CVs) were low for P2, N2 and P4 peak times, but higher for all amplitudes. There were no statistically significant differences comparing peak times and amplitudes between eyes or between sessions. Coefficients of repeatability (CRs) are reported for P2, N2 and P4 peak times between eyes (P2; 5 ms, N2; 18 ms, P4; 18 ms) and also between sessions (P2; 5 ms, N2; 16 ms, P4; 39 ms). Intraclass correlation coefficients (ICCs), as an estimate of test-retest reliability, was assessed to be fair to excellent for most parameters. Conclusions: This study provides important data on variability, repeatability and test-retest reliability of FVEPs in normal, adult horses. We conclude that P2, N2 and P4 peak times should be included in the evaluation of equine FVEPs. The large inherent variability of FVEP amplitudes is likely to make them less suitable and useful for establishing a diagnosis on their own in most clinical patients, but they may occasionally provide support to a clinical diagnosis.
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Publication Date: 2020-07-29 PubMed ID: 32727477PubMed Central: PMC7389813DOI: 10.1186/s12917-020-02463-8Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research focuses on understanding the variability, repeatability, and reliability of Flash Visual Evoked Potentials (FVEPs) in horses. The researchers found that certain aspects of the FVEPs were consistent, while others had higher variability. This study establishes a foundation for future studies and clinical diagnoses using equine FVEPs.

Understanding Visual Evoked Potentials (VEPs) and Flash Visual Evoked Potentials (FVEPs)

  • Visual Evoked Potentials (VEPs) are electrical potentials that are produced by neurons within the central nervous system as they respond to visual stimuli.
  • These responses can be recorded as a series of wavelets (positive and negative) in reaction to flash-stimuli, which are referred to as Flash Visual Evoked Potentials (FVEPs). Another type of VEPs can be generated by using iso-luminant patterns, which are termed as Pattern VEPs (PVEPs).
  • Any pathological conditions impacting the pathways beyond the retina can result in changes to the wavelet’s peak times and amplitudes as well as their overall waveform morphology.
  • FVEPs are a recent development in equine clinical research, calling for more data aimed at understanding intra-individual and inter-individual differences.

Focus and Findings of the Study

  • The primary purpose of this research was to analyze the variability, repeatability, and test-retest reliability of equine FVEPs.
  • Experiments were performed on 17 horses, using one eye randomly selected in each case.
  • The analysis identified the presence of N1, P2, N2 and P4 wavelets in all the recorded FVEPs. Other wavelets like P1, N2a, P3 and P5, however, were found to be less frequent.
  • It was found that the variability (expressed as coefficients of variation or CVs) was low for peak times of P2, N2 and P4 wavelets, but significantly high for all amplitude values.

Repeatability and Reliability Assessment

  • No significant differences were found when comparing peak times and amplitudes between eyes or between different sessions.
  • Repeatability was determined by comparing the peak times of P2, N2 and P4 wavelets between the eyes and between different sessions. The study reported Coefficients of Repeatability (CRs) values for these wavelets.
  • The Intraclass correlation coefficients (ICCs), used as estimates for test-retest reliability, were found to display fair to excellent values for most of the parameters considered in the study.

Conclusions and Implications

  • This study enriches the knowledge around the variability, repeatability and reliability of equine FVEPs, setting a standard for future studies and clinical diagnoses using this method.
  • The researchers suggest that clinicians should consider evaluating P2, N2 and P4 peak times when interpreting equine FVEPs.
  • The researchers do caution that the high inherent variability in FVEP amplitudes may limit their utility for standalone diagnosis in clinical settings, but these measures could support clinical diagnoses in some cases.

Cite This Article

APA
Ström L, Bröjer J, Ekesten B. (2020). Variability, repeatability and test-retest reliability of equine flash visual evoked potentials (FVEPs). BMC Vet Res, 16(1), 261. https://doi.org/10.1186/s12917-020-02463-8

Publication

BMC veterinary research
ISSN: 1746-6148
NlmUniqueID: 101249759
Country: England
Language: English
Volume: 16
Issue: 1
Pages: 261
PII: 261

Researcher Affiliations

Ström, L
  • Department of Clinical Sciences, Swedish University of Agricultural Sciences, PO Box 7054, SE-750 07, Uppsala, Sweden. lena.strom@slu.se.
Bröjer, J
  • Department of Clinical Sciences, Swedish University of Agricultural Sciences, PO Box 7054, SE-750 07, Uppsala, Sweden.
Ekesten, B
  • Department of Clinical Sciences, Swedish University of Agricultural Sciences, PO Box 7054, SE-750 07, Uppsala, Sweden.

MeSH Terms

  • Animals
  • Evoked Potentials, Visual
  • Female
  • Horses / physiology
  • Male
  • Reproducibility of Results

Conflict of Interest Statement

The authors declare that they have no competing interests.

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Citations

This article has been cited 2 times.
  1. Itoh K, Kikumura N, Maeda T, Hirata S, Ringhofer M. Non-invasive scalp recording of electroencephalograms and evoked potentials in unanesthetized horses using a 12-channel active electrode array. Front Vet Sci 2024;11:1470039.
    doi: 10.3389/fvets.2024.1470039pubmed: 39687848google scholar: lookup
  2. Elsaid MAM, Soliman S, Hashem O. Changes in the Parameters of Visual Evoked Potentials in Media Opacities. Clin Ophthalmol 2023;17:3261-3270.
    doi: 10.2147/OPTH.S423526pubmed: 37927575google scholar: lookup
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