[Nerve fibre bundle defects in a pre-chiasmal lesion].

Background: Prechiasmal lesions of the visual pathway are produced by visual field defects that either affect only one eye or, if both eyes are affected, they are clearly different. Typically, the defects respect the vertical meridian. This report of a case shows that the classical nerve fibre bundle defect must be taken into consideration for differential diagnosis.
Case Report: In a 67-year-old patient, a meningeoma of the sphenoid was diagnosed that had spread into the optic canal. Examination of the visual field showed an inferior altitudinal nerve fibre bundle defect.
Conclusions: Apparently the retinal pattern of nerve fibres remains intact even when approaching the optic chiasm. Nerve fibre bundle defects are therefore sometimes found in prechiasmal lesions and should be considered for differential diagnosis (e. g., in the case of a suspected low tension glaucoma).