■ With multifocal visual evoked potentials (mfVEPs) the visual field can be sampled for response abnormalities. Thus, mfVEPs
open the possibility of an objective visual field test. The issue, however, is greatly complicated by the variability of the
responses across the visual field and between subjects.
■ Cortical morphology dictates the mfVEP shape and influences mfVEP magnitude; consequently it is one important cause of the
variability of mfVEPs. Thus for some visual field locations severe signal loss can occur, which mimics scotomata. The number
of these spurious scotomata can be reduced by recording from multiple electrodes. To account for the cortical magnification
of the visual field representation specifically scaled circular checkerboard patterns are used for stimulation.
■ While different strategies proved successful for the evaluation of mfVEP magnitude and latency, root-meansquare calculations
and correlations of the responses with reference traces have the advantage of being based on a number of points as opposed
to single peak values and yield reliable estimates of response magnitude and latency.
■ Estimates of mfVEP magnitude, latency, and cortical topography are valuable tools for the assessment of visual function.
Multifocal VEP magnitude is particularly valuable for an objective visual field assessment in glaucoma patients. Multifocal
VEP latency measures promise further insight into visual system abnormalities in patients with optic neuritis and multiple
sclerosis. Multifocal VEP topography can help to detail malformation of the optic chiasm, e.g., in albinism.