Abstract
Abstract: :
Purpose:It is widely accepted that blue/yellow subjective perimetry can detect glaucomatous abnormalities and their progression earlier than standard white on white perimetry.The aim of this study is to investigate sensitivity of blue/yellow multi–focal Visual Evoked Potentials (BYmVEP) in the detection of glaucomatous visual field defects. Methods: 20 glaucoma patients underwent subjective and objective perimetry testing. Subjective perimetry included the Humphrey visual fields (HVF) using Swedish Interactive Threshold Algorithm (SITA) and Short Wave Automated Perimetry (SWAP). Monocular mVEPs were also recorded using the AccuMap perimeter under two different stimulation conditions: black–white and blue–yellow. 41 age matched normal subjects were also recorded using BYmVEP protocol to calculate normative values. Results of the subjective and objective testing were compared. Results: 28 glaucomatous eyes had abnormal HVF and 12 fellow eyes had normal fields despite suspicious discs. In the group of glaucomatous eyes, 3 eyes with early defects (MD<6) were classified as normal by SWAP with 25 eyes classified as abnormal. However all the eyes were detected as abnormal by both BW and BYmVEPs. In many cases, the extent of the visual field defect was greatest on BYmVEP, Of the 12 fellow eyes with normal HVF, 1 eye demonstrated abnormalities on all three additional tests. A further 4 cases resulted in abnormal bw and bymVEPs, whilst an additional 4 were detected as abnormal on bymVEP alone. Further hemifield analysis of the 28 glaucomatous fields demonstrated sensitivity of three methods as follow: 83% SWAP, 97.6% BWmVEP and 100% BYmVEP, while an.additional 2 hemifields were detected as abnormal using SWAP, 6 with bw–mVEPS and 11 with by–mVEPs. Conclusions: Our findings suggest that blue–yellow mVEP is a viable method for detecting early glaucomatous visual field defects.
Keywords: perimetry • visual fields • electrophysiology: clinical