lesions at the level of the optic chiasm
Last reviewed 01/2018
Lesions at the level of the optic chiasm result in a bitemporal hemianopia.
Tumours of the pituitary may initially present with a bitemporal upper quadrantic defect which progresses to a bitemporal hemianopia.
This is because they only interfere with the decussating fibres, which are those fibres from the nasal retina that sense images from the temporal visual field.