The symptoms of lesions producing pressure on the optic chiasm are extremely variable. While various bitemporal hemianopic defects are the most frequent and most characteristic type of changes found in the perimetric fields, asymmetrical or incongruous altitudinal anopsias and homonymous hemianopias are frequently encountered. Unilateral or bilateral complete amaurosis is ascribed usually to a lesion of the optic nerve proper, and in the absence of an ophthalmoscopically visible explanation for its presence it is usually interpreted as evidence of a lesion in the chiasm or in the optic nerve anterior to the chiasm.
In association with choked disks, defects in the perimetric fields suggesting pressure on the prechiasmal portions of the optic nerves or on the optic chiasm itself are interpreted usually as evidence of basofrontal tumor, suprasellar tumor of the Rathke pouch type or tumor of the third ventricle. Ordinarily these diagnoses will be correct. Occasionally, however, evidence
WAGENER HP, CUSICK PL. CHIASMAL SYNDROMES PRODUCED BY LESIONS IN THE POSTERIOR FOSSA. Arch Ophthalmol. 1937;18(6):887–891. doi:10.1001/archopht.1937.00850120021001