Visual dysfunction with basal skull tumours.

Early detection of visual loss caused by tumours of the base of the skull is accomplished by systematic tests of the pregeniculate optic pathway. Even when central acuity is relatively preserved, a relative afferent pupillary defect and reduced color perception yield evidence of impaired optic nerve conduction. Although confrontation tests of the visual fields are useful screening techniques, unexplained symptoms should be pursued with static and kinetic perimetry. Patterns of optic nerve and chiasmal field loss and atrophy of the dis or retinal nerve fibers are imprecise guides to the location of basal skull tumours. Regardless of the pattern of visual field defect, unexplained progressive loss of vision demands intensive neuroradiologic study of the basal cisterns and skull.