VISUAL EVOKED-POTENTIALS IN COMPRESSIVE LESIONS OF THE OPTIC CHIASM

VEP abnormalities, radiologic CT findings and visual field defects are presented in 33 patients with compressive lesions of the optic chiasm. VEP abnormalities indicated either only dysfunction of crossed fibres or dysfunction of both the crossed and uncrossed fibres. Temporal and nasal visual field defects were consistent with VEP abnormalities obtained by temporal and nasal half-field stimulation. CT findings showing extensive lesions were predominately associated with abnormal temporal and nasal half-field VEPs. This study shows that aside from visual acuity, visual field and CT scan examinations in patients with suspected chiasmal dysfunction, VEP is an important adjunct for assessing the function of the optic chiasm.