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P. Thienprasiddhi, D.C. Hood, V.C. Greenstein, B.J. Winn, S. Zafar, J.M. Liebmann, R. Ritch; Can the Multifocal VEP Detect Early Field Abnormalities in Glaucoma Suspects? . Invest. Ophthalmol. Vis. Sci. 2003;44(13):31.
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Purpose: To determine whether the multifocal visual evoked potential (mfVEP) can detect field abnormalities in ocular hypertensive (OHT) and glaucoma suspect (GLS) patients with normal achromatic perimetry results. Methods: Thirty-two GLS patients with glaucomatous optic disc and 15 OHT patients were included in this study. The criteria for GLS included vertical cup-disc ratio>=0.6, and/or a disc asymmetry>=0.2, and /or parapapillary nerve fiber layer defect, and/or disc notching, and/or disc hemorrhage. The criteria for OHT were intraocular pressure>=22 mmHg and normal optic discs. All patients had normal achromatic perimetry, as defined by a PSD within 95% and a glaucoma hemifield test within 99% on the Humphrey visual field (HVF) 24-2 program. Monocular mfVEPs were obtained from each eye using a pattern-reversal dartboard array, 44.5 deg in diameter, and containing 60 sectors. Recording electrodes were placed at the inion (I) and I+4 cm, and also at two lateral locations up 1 cm and over 4 cm from I. Monocular and interocular analyses were performed [1,2]. For both HVF (pattern deviation plot) and mfVEP tests, a hemifield was defined as abnormal based on a cluster test [3,4], if 2 or more contiguous points had p<0.01, or 3 or more contiguous points had p<0.05 with at least one of these points with p<0.01. An eye was defined as abnormal if either or both hemifields had a cluster of abnormal points. Results: Of the 94 GLS and OHT eyes, 37 eyes (39%) had abnormal mfVEP and 16 (17%) eyes had abnormal HVF. Of the 188 hemifields, the mfVEP was abnormal in 56 (30%) hemifields and the HVF was abnormal in 17 (9%) hemifields. In the 17 hemifields with an abnormal HVF, 10 hemifields (59%) also had abnormal mfVEP clusters. The results for both GLS and OHT groups were similar. Conclusions: The mfVEP can detect field defects in GLS and OHT eyes that are not detected by achromatic automated perimetry. However, the reverse can be true as the mfVEP can be normal in eyes with abnormal HVFs. Ref: 1.Hood et al (2002) AO. 2.Hood and Greenstein (2003) Prog Ret Eye Res. 3.Chauhan et al (1998) Doc Ophth 4. Goldberg et al (2002) AJO.
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