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VC Greenstein, X Zhang, P Thienprasiddhi, JM Liebmann, R Ritch, S Giannikakis, DC Hood; Comparing Visual Field Sensitivity and Multifocal VEP Responses to Structural Changes in the Optic Nerve Head . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2161.
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Purpose: To develop a method for comparing structural changes in the optic nerve head to multifocal visual evoked potential (mfVEP) responses and to behaviorally determined visual fields. Methods: Twelve patients with open-angle glaucoma were enrolled in the study. Humphrey 24-2 visual fields were obtained from each eye and optic disks were assessed with a confocal scanning laser ophthalmoscope (HRT). Monocular mfVEPs were obtained from each eye using a pattern-reversal dartboard array with 60 sectors; the entire display was 44.5 degrees in diameter. The four recording electrodes were placed at the inion (I) and I+4 cm, and at two lateral locations up 1 cm and over 4 cm. A root-mean-square (RMS) amplitude and a signal-to-noise-ratio (SNR) were obtained for each response from the 6 possible channels (three recorded and three derived) [1,2]. The best channel in terms of the SNR for each of the 60 sectors was analyzed. Optic disc damage for each eye was evaluated by calculating rim area ratios (rim area/total rim area) in 10-degree sectors. Interocular rim ratios, visual field ratios and mfVEP ratios were calculated for each patient. The topographic relationship of the optic disc measurements to mfVEP responses and visual field sensitivities was assessed by dividing the 36 sectors of the optic disc, the 24-2 Humphrey visual field and the 60 sectors of the mfVEP into 6 zones as defined by Garway-Heath et al . Results: Defects on the optic disc were topographically related to specific damaged visual field and mfVEP zones. In addition, four patients who showed mfVEP defects in zones with normal visual field results, had optic disc damage in the corresponding sectors. Conclusion: With this method, the mfVEP and visual field deficits can be quantitatively mapped to known structural defects in patients with glaucoma. 1. Hood et al (2000), IOVS 2. Zhang et al, (in press) Doc Oph 3. Garway-Heath et al., Ophthal 2000.
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