Bitemporal hemianopic field defect is characteristic of:

Ans. is 'c' i.e. Pituitary tumour Bitemporal hemianopia results due to central (sagittal) lesion of the optic chiasma, common causes of which are tumors of the pituitary gland, craniopharyngioma, suprasellar meningioma, glioma of third ventricle, chiasmal arachnoiditis, third ventricular dilatation.Sites of lesion of visual path and corresponding field defects. Site of lesionField defect1. Optic nerveIpsilateral blindness2. Proximal part of ONIpsilateral blindness with contralateral hemianopia or superior quadrantanopia3. Central lesion of chiasmaBitemporal hemianopia4. Optic tractHomonymous hemianopia5. Temporal lobeQuadrantic homonymous defect6. Optic radiationHomonymous hemianopia7. Anteriorly in occipital cortexContralateral temporal crescentic field defect8. Occipital lobeHomonymous hemianopia (usually sparing the macula)