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Prema Sriram, Alexander Klistorner, Hemamalini Arvind, Stuart L. Graham; Reproducibility of Latency Using Different Stimulus Presentations on Multifocal VEP. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6085.
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© ARVO (1962-2015); The Authors (2016-present)
To study the reproducibility of latency of multifocal visual evoked potential (mfVEP) with 3 ring stimulus geometry and different stimulus presentations, and to identify the peak with least variability.
Ten normal subjects, aged between 22 and 52 years (mean age 32 ± 8.37 yrs) participated in the study. All subjects underwent mfVEP testing with Pattern-reversal and Pattern-onset stimulus presentations on 3- ring stimulus geometry. The 3 ring geometry subtends 26 degrees from fixation and includes 24 segments. Only the vertical channel was recorded on all subjects. The tests were repeated after 1-2 weeks. Both the eyes were tested, but only the right eye of all subjects was included in the study. Segments with low signal to noise rations (SNR<1.5) were excluded from analysis. The latencies were analysed to confirm values from the same peak for the two tests. The latency values were then analysed for the start of the response, the 1st peak and the 2nd peak. The mean differences in latencies between the two sessions were calculated to assess the test retest variability.
The waveforms were reproducible throughout the field, with the exception of some superior rim points. These often had small amplitudes and were therefore excluded from analysis in some subjects. The test retest variability for the start of the response pattern-reversal and pattern-onset were 12.34 ± 4.03 ms and 9.18 ± 1.83 ms, 3.18 ± 1.22 ms and 4.52 ± 2.39 ms for the 1st peak and 4.31 ± 2.02 ms and 7.89 ± 3.16 ms for the 2nd peak respectively. The start of the response was highly variable on both pattern reversal and pattern onset stimulus presentations and therefore not a useful parameter. However, there was no significant difference between the 1st and the 2nd peak latencies on the pattern reversal presentation (p=0.708). There was a significant difference noted between the two peaks on the pattern onset presentation (p=0.008).
The latencies on vertical channel mfVEP were found to be more reproducible with pattern reversal stimulus presentations and the 1st peak showed the least variability. Latencies from multiple channel recordings require more detailed evaluation.
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