Receiver-operating characteristic analysis of multifocal VEPs to diagnose and quantify glaucomatous functional damage

To test whether multifocal visual evoked potential (mfVEP) recording using two perpendicularly placed channels, as previously reported, to measure the degree of signal-to-noise ratio (SNR) distribution overlap between a signal window and a noise window would efficiently detect and quantify glaucomatous damage. Humphrey visual field (HVF) and mfVEP were recorded from 56 patients with primary open-angle glaucoma and mean deviation less than -15 dB and 62 age-matched ophthalmologically normal individuals. Areas under the receiver-operating characteristic curve (SNR-AUC) were calculated based on the proportion of mfVEP responses that exceeded a specific SNR criterion for both windows. Abnormal sectors with an SNR deviated from the previously established norm with P<5% and 1% were counted. Diagnostic accuracy of the SNR-AUC was similar to that of the average total deviation (TD) of the HVF. The hemifield agreement to detect a defect in mfVEP and HVF was 77.1-87.3%, which was similar to previous reports using multiple channels. Correlation coefficients between SNR-AUC and average TD (0.74 in the upper hemifield and 0.65 in the lower) were significantly higher than those between the sums of abnormal locations on the mfVEP and HVF probability plots (0.27 and 0.33, respectively). Two perpendicular channels can detect and quantify functional damage due to glaucoma. The SNR-AUC may be used as a global index to quantify diffuse glaucomatous functional loss.