Large pituitary tumour results in
(C) Bitemporal hemianopia # Visual field defects are caused by tumor compression on the optic nerve or chiasm leading to axonal damage.> Depending on the size and location of the tumor, as well as the anatomical relationship of the chiasm to the pituitary stalk, the severity and symmetry of the visual field defect may vary.> Monocular Visual Field Deficits: Asymmetric tumors may preferentially involve one side of the chiasm or an optic nerve, and most commonly presents as a supertemporal quadrantanopia. The incidence of pituitary adenomas presenting as monocular visual field defects was reported to be 9% (in a series of 1,000 patients). If the presenting symptom is sudden monocular visual loss, a pituitary adenoma may be acutely missed, as other more common etiologies are evaluated. Another consideration for sudden monocular visual loss is pituitary apoplexy, though visual field evaluation is often deferred due to the emergent nature of this condition. Monocular temporal hemianopia are not always indicative of a pituitary tumor. These defects, especially in the setting of no Relative afferent pupillary defect or optic atrophy, may suggest functional (non-organic) vision loss. Functional vision loss in the setting of a monocular temporal hemianopsia can be confirmed by the persistence of the temporal hemianopia on binocular visual field testing.> Chiasmal Field Deficits: Characteristically lesions at the level of the optic chiasm produce a bitemporal hemianopia. Pituitary adenomas, which grow upward from the pituitary stalk, compress the chiasm from below, which preferentially involves the inferior, nasal, and macular nerve fibers. This corresponds to superior, bitemporal, and central vision loss. While these field defects typically respect the vertical midline, pituitary adenomas large enough to cause compression tend to also reduce visual acuity and cause diffuse central depression on automated and Goldmann perimetry. In prefixed chiasms or tumors that preferentially grow posteriorly, selective compression of macular fibers may cause a bitemporal hemianopsia involving the central visual field while sparing the peripheral field.> Junctional Field Deficits:- Phenomenon of a central scotoma in one eye with temporal visual field loss in the other eye has been termed a junctional scotoma. Anatomical correlate to this visual field pattern has been suggested by some as compression to an anterior loop to the decus- sating nasal fibers within the posterior optic nerve.> This explanation, called "Wilbrand's knee," is debated within the literature; regardless of the cause, multiple studies nave proven that this visual field phenomenon localizes the lesion to the anterior chiasm and posterior optic nerve.> While junctional field defects have been the presenting sign of pituitary adenomas, it is more commonly seen in other etiologies (meningioma, aneurysm, inflammation).
Unilateral quadrantanopia
Increase in blind spot only
Bitemporal hemianopia
Binasal hemianopia
Miscellaneous