Abstract
Purpose: :
The pattern multifocal Visual Evoked Potential (mVEP) using black/white checks has been reported to detect glaucomatous visual field defects in moderate and advanced glaucoma with up to 100% sensitivity[1]. However, about 5% of cases with early glaucomatous field defect were missed by the mVEP technique. The aim of this study is to investigate sensitivity of a new Blue–on–Yellow mVEP (BonY mVEP) in the detection of early glaucomatous visual field defects.
Methods: :
A BonY mVEP using sparse presentations[2] of a pattern of blue checks on a bright yellow background was recorded monocularly in 28 glaucoma patients. 35 age–matched normal subjects were also recorded to calculate normative amplitude values, which were then used to construct amplitude and asymmetry deviation plots. Recording duration was only 5 min per eye. 58 segments of the visual field were tested. All patients also underwent SWAP visual fields
Results: :
35 glaucomatous eyes had abnormal Humphrey visual field (HVF) and 21 fellow eyes had normal fields. In the group of glaucomatous eyes BonY mVEP detected the scotoma in all cases (100%). Of the 21 fellow eyes with normal HVF, 4 eyes (19%) also demonstrated abnormalities on BonY mVEP. Further hemifield analysis of the glaucomatous fields demonstrated high topographic correspondence between HVF and BonY mVEP with only one HVF defect (nasal step) missed and 9 additional hemifields detected as abnormal by BonY mVEP. SWAP fields showed surprisingly less confirmed defects according to our definition of a scotoma (3 abnormal pts at least 2 non rim points depressed <0.5%).
Conclusions: :
Our preliminary findings suggest that Blue–on–Yellow mVEP is a viable method for fast objective detection of early glaucomatous visual field defects.
Keywords: electrophysiology: clinical • visual fields