Visual field defect seen in pituitary tumour is: March 2012

Ans: A i.e. Bitemporal hemianopia Visual field defects Bitemporal hemianopia is usually caused by tumours in the region of the sella turcica (tumours of the pituitary body are most common), pressure by a suprasellar aneurysm or by chronic archnoiditis; these presses upon chiasma, so that the fibres going to the nasal halves of each retina are destroyed Occipital lobe hemianopias are extremely congruous, having a homogenous density with sparing of the macula Binasal hemianopia (rare) may be due to distension of the third ventricle, causing the optic nerves to be pressed downwards & outwards against the internal carotids, or to atheroma of the carotids or posterior communicating aeries Homonymous quadrantanopia may be caused by coical or subcoical paial lesions of one occipital lobe, destruction of the pa above the calcrine fissure leading to loss of the lower quadrants & vice versa