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S.L. Graham, A. Klistorner, C. Balachandran, I. Goldberg; Intrasubject Variability of Multifocal VEP in Normals and Glaucoma . Invest. Ophthalmol. Vis. Sci. 2003;44(13):45.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To examine the intrasubject variability of objective perimetry using the multifocal visual evoked potential (mVEP). Methods: In 22 normals and 22 glaucomas the mVEP was recorded on 2 separate occasions 4 weeks apart using the AccuMap system (ObjectiVision,Sydney Australia). The test recorded multichannel mVEP responses from 58 zones out to 32 degrees eccentricity. Four channels were recorded using a fixed electrode cross position applied over the inion. The cross was reapplied at the same site for the second test and verified by measuring the vertical distance from the cross to the nasal bridge. Humphrey visual fields (SITA 24-2) were also performed. Comparison of amplitudes between tests was then conducted by using log Test 2/Test1 for each of the 58 points of the trace array. Results: Average variability coefficient for the normals was 0.185 +/- 0.03, variability for the glaucoma group was 0.187+/- 0.03. The difference was not significant p=0.7. The variability was slightly increased with eccentricity in normals (0.175-0.195 inner to outer rings), but there was no change in the glaucoma groupConclusions: The variability is similar to that previously reported for normals with an earlier version of the AccuMap system (Goldberg et al, AJO 2002). In glaucomas we found similar test-retest variability. Further analysis of variability within scotomas needs to be performed to determine the utility of the test in detecting change.
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