Multifocal Blue-on-Yellow Visual Evoked Potentials in Early Glaucoma
Received 27 June 2006; received in revised form 23 November 2006; accepted 28 November 2006.
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.
1Department of Ophthalmology, Save Sight Institute, University of Sydney, Sydney, Australia.
2Research School of Biological Sciences and ARC Centre of Excellence in Vision Science, Australia National University, Canberra, Australia.
Correspondence to Alexander Klistorner, PhD, P.O. Box 4337, Sydney, 2001, NSW, Australia.
Manuscript no. 2006-701.
Supported by ORIA and Sydney Medical Foundation, Sydney, Australia (research fellowship [AK]).
1 Drs Klistorner and Graham have a financial interest in the Accumap, being coinventors of the machine and acting as consultants to ObjectiVision. They are both involved in the ongoing research and development of this product.
2 Dr James is a nominated coinventor of patents for the sparse stimulation technique.
ABSTRACT