Visual field defect in pituitary tumour with supracellular extension is: March 2011

Ans. A: Bitemporal hemianopia Bitemporal hemianopia is usually caused by tumours in the region of the sella turcica, pressure by suprasellar aneurysm or by chronic arachnoiditis; these press upon the chiasma, so that the fibres from the nasal halves of each retina are destroyed Bitemporal hemianopsia/ Bitemporal hemianopia It is a type of paial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary gland Causes In bitemporal hemianopsia vision is missing in the outer (temporal or lateral) half of both the right and left visual fields. Information from the temporal visual field falls on the nasal (medial) retina. The nasal retina is responsible for carrying the information along the optic nerve, and crosses to the other side at the optic chiasm. When there is compression at optic chiasm the visual impulse from both nasal retina are affected, leading to inability to view the temporal, or peripheral, vision. This phenomenon is known as bitemporal hemianopsia. Bitemporal hemianopsia most commonly occurs as a result of tumors located at the mid-optic chiasm. Since the adjacent structure is the pituitary gland, some common tumors causing compression are pituitary adenomas, and craniopharyngiomas. Also another relatively common neoplastic etiology is meningiomas. An etiology of vascular origin is an aneurysm of the anterior communicating aery which arise superior to the chiasm, enlarge, and compress it from above.