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M. Gabriele, G. Wollstein, H. Ishikawa, A.A. Bonfioli, W.D. Dilworth, Z. Burgansky, R.J. Noecker, J.S. Schuman; Reproducibility of Multifocal Visual Evoked Potential Recordings . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2488.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To evaluate the intervisit and intravisit reproducibility of four–electrode multifocal visual evoked potential (mfVEP) recordings (AccuMap, ObjectiVision, Sydney, Australia; Version 2.1.1). Methods:Five healthy subjects (10 eyes) were tested with AccuMap over two sessions. Inclusion criteria were a best corrected visual acuity of 20/30 or better and refractive error below 6D or 3D cylinder. Four electrodes placed over the inion were used to detect electrical potentials generated by occipital cortex cells during visual stimulation, and an array of traces from each of 58 stimulated segments was generated for each eye and trace amplitudes were compared with normative data to identify localized areas of defect. The first session involved two consecutive recordings without altering electrode position, randomizing which eye was tested first. Subjects returned on a separate day for the second session of two more consecutive recordings, with the order of testing reversed from session one. There were a total of four recordings for each eye. A reliable test had a total noise level ≤30%. Intravisit and intervisit variability were computed using standard deviation (SD) and coefficient of variance (CV) of the AccuMap Severity Index (ASI). Subjective assessment of agreement was based on the location and number of scotomas (3 adjacent points on the amplitude deviation trace map with p<0.05), and number of abnormal points (p<0.05) in each scotoma. Results: Mean subject age was 36 ± 10 years, and the average time between sessions was 3.2 ± 5 days. Overall intravisit ASI SD was 11.9 with a CV of 0.869, higher than the overall intervisit ASI SD of 6.0 and CV of 0.690. Although all participants had normal standard achromatic perimetry (SAP) tests, subjective assessment of the amplitude deviation trace map identified defects in 4 of the 10 eyes. Within those 4 eyes, the overall mean difference in the number of defects between the first and second sessions was 0.5. The mean number of abnormal points in the first session was 10.3 and 10.0 in the second (p=0.88), and the mean difference in defect size was 4.1 abnormal points. Conclusions:AccuMap showed poor reproducibility of visual field measurements in this healthy group. The detection of defects that were not detected by SAP might indicate earlier detection or false positive results by this modality.
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