You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Bitemporal hemianopia is caused by lesions at and explain in detail?
(Central lesion of the Chiasma) (290-Khurana 4rd) (35-P)LESIONS OF THE VISUAL PATHWAY1. Lesions of the optic nerve - Marked loss of vision or complete blindless on the affected side associated with abolition of the direct light reflex on the ipsilateral side and consensual on the contralateral side.Common causes - Optic atrophy, Traumatic avulsion of the optic nerve, Indirect optic neuropathy and acute optic neuritis2. Lesions through proximal part of the optic nerve - Ipsilateral blindness, contralateral hemianopia and abolition of direct light reflex on the affected side and consensual on the contralateral side, Near reflex is intact.3. Sagittal (Cental) lesions of the Chiasma - Bitemporal hemianopia and bitemporal hemianopic paralysis of the pupillary reflexes.Common causes - Suprasellar aneurysm, tumours of the pituitary glands*, Craniopharyngioma, suprasellar Meningioma, glioma of third ventricle, third ventricular dilatation due to obstructive hydrocephalus and chronic chiasmal arachnoiditis.4. Lateral chiasmal lesions - Binasal hemianopia associated with binasal hemianopic paralysis of the pupillary reflexes.Common causes are - Distension of third ventricles causing pressure on each side of the chiasma, and atheroma of the carotids or posterior communicating arteries.5. Lesions of the optic tract - in congruous homonymous, hemianopia associated with contralateral hemianopic pupillary reactions {Wernicke's reaction)Common causes are - syphilitic meningitis or gumma, TB and tumours of optic thalamus and aneurysms of superior cerebellar or posterior cerebral arteries.6. Lesion of the lateral geniculate body - homonymous hemianopia with sparing of pupillary reflexes and may end in partial optic atrophy7. Lesions of optic radiation(I) Inferior quadrantic hemianopia {Pie on the floor) - lesions of parietal lobe(II) Superior quadrantic hemianopia {Pie in the sky) lesions of the temporal lobes