Multifocal Blue-on-Yellow Visual Evoked Potentials in Early Glaucoma

Abstract

Objective: To determine the sensitivity and specificity of blue-on-yellow multifocal visual evoked potentials (mfVEPs) in early glaucoma. Design: Cross-sectional study. Participants: Fifty patients with a confirmed diagnosis of early glaucoma and 60 normal participants. Methods: Black-and-white mfVEPs and blue-on-yellow mfVEPs were recorded using the Accumap version 2.0 (ObjectiVision Pty. Ltd., Sydney, Australia). All patients also underwent achromatic standard automated perimetry (SAP). Main Outcome Measures: Multifocal VEP amplitude and latency values in glaucoma patients were analyzed and compared with those of the normal controls. Results: Based on the definition of visual field defect, in the group of glaucomatous eyes with SAP defects, amplitude of blue-on-yellow mfVEP was abnormal in all 64 cases (100% sensitivity), whereas black-and-white mfVEP missed 5 cases (92.2% sensitivity). Generally, larger scotomata were noted on blue-on-yellow mfVEP compared with black-and-white mfVEP for the same eyes. There was high topographic correspondence between SAP and amplitude of blue-on-yellow mfVEP and significant (P<0.0001) correlation between them (correlation coefficient, 0.73). Abnormal amplitude was detected in 3 of 60 eyes of control subjects (95% specificity). There was, however, no correlation between visual field defect and latency delay in glaucoma patients. Although there was a significant difference between averaged latency of control and glaucoma eyes, values considerably overlapped. Conclusions: The blue-on-yellow mfVEP is a sensitive and specific tool for detecting early glaucoma based on amplitude analysis. Show more