Clinical application of the multifocal VEPs

Abstract

Purpose. To determine whether visual field defects can be detected by the multifocal VEP technique. Methods. Multifocal VEPs were elicited by a pseudorandom binary m-sequence stimulus (VERIS II). The stimulus was a dartboard-like pattern of 61 sectors, and the luminance of each sector alternated between white and black. The stimulus area subtended approximately 25 degrees. Each recording was divided into 8 equal segments, and the total recording time was about 4 min. Multifocal VEPs were recorded from 25 normal subjects and six patients with visual field loss. The responses summed within 4 quadrants were used in the analysis and were compared with the visual fields obtained by perimetry. Results. In six perimetrically-documented visual field defects, the responses summed over each quadrant of the field were reduced in the corresponding affected quadrants. In addition, recovery of the visual field loss following treatment was accompanied by a recovery of the responses. Conclusions. Multifocal VEPs summed within four quadrants can be used for an objective evaluation of the visual fields. The testing can be obtained in 4 min with no pain or discomfort to the patient.