Exploring the methods of data analysis in multifocal visual evoked potentials
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The multifocal visual evoked potential (mfVEP) provides a topographical assessment of visual function, which has already shown potential for use in patients with glaucoma and multiple sclerosis. However, the variability in mfVEP measurements has limited its broader application. The purpose of this study was to compare several methods of data analysis to decrease mfVEP variability.
Twenty-three normal subjects underwent mfVEP testing. Monocular and interocular asymmetry data were analyzed. Coefficients of variability in amplitude were examined using peak-to-peak, root mean square (RMS), signal-to-noise ratio (SNR) and logSNR techniques. Coefficients of variability in latency were examined using second peak and cross-correlation methods.
LogSNR and peak-to-peak methods had significantly lower intra-subject variability when compared with RMS and SNR methods. LogSNR had the lowest inter-subject amplitude variability when compared with peak-to-peak, RMS and SNR. Average latency asymmetry values for the cross-correlation analysis were 1.7 ms (CI 95 % 1.2–2.3 ms) and for the second peak analysis 2.5 ms (CI 95 % 1.7–3.3 ms). A significant difference was found between cross-correlation and second peak analysis for both intra-subject variability (p < 0.001) and inter-subject variability (p < 0.001).
For a comparison of amplitude data between groups of patients, the logSNR or SNR methods are preferred because of the smaller inter-subject variability. LogSNR or peak-to-peak methods have lower intra-subject variability, so are recommended for comparing an individual mfVEP to previous published normative data. This study establishes that the choice of mfVEP data analysis method can be used to decrease variability of the mfVEP results.
KeywordsMultifocal visual evoked potentials Inter-subject variability Intra-subject variability Coefficient of variability Data analysis
This research was partially supported by Værn om Synet, Synoptik-Fonden, Kleinsmed Svend Helge Arvid Schröder og Hustrus Fond and by the Spanish government Grant: TEC2011-26066.
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Conflict of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership or other equity interest; and expert testimony or patent-licensing arrangements) or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.
This research was partially supported by Værn om Synet, Synoptik-Fonden, Kleinsmed Svend Helge Arvid Schröder og Hustrus Fond and by the Spanish government Grant: TEC2011-26066 in the form of Ph.D. salary. The sponsors had no role in the design or conduct of this research.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
Statement of human rights
The study was performed in accordance with Universal Declaration of Human Rights.
Statement on the welfare of animals
This article does not contain any studies with animals.
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