6th Sep 2012 by 
Upper Altitudinal Hemianopia
Altitudinal hemianopia comprises defective vision in the upper or lower horizontal half of the visual field. It may be unilateral or bilateral; unilateral field defect is prechiasmal.
Upper Altitudinal Hemianopia is caused as a result of destruction of bilateral destruction of lingual gyri.
Lower Altitudinal Hemianopia is caused as a result of destruction of bilateral destruction of cunei.
Lower Altitudinal Hemianopia
Causes
- Anemia-produces bilateral inferior altitudinal hemianopia
- Anterior ischemic optic neuropathy
- Bilateral branch retinal artery occlusion
- Fusiform aneurysms (arteriosclerotic or congenital)-may produce inferior altitudinal hemianopia by pressure against the lateral halves of the optic chiasm or nerve
- Herpes zoster
- Lesion that presses the chiasm upward against the superior margin of the optic foramen
- Occipital lobe lesions
- Olfactory groove meningioma extending posteroinferior to compress the intracranial portion of the optic nerve
- Optic-nerve lesion
- Sclerotic plaques of internal carotid artery or anterior cerebral arteries-pressure of plaques on optic nerve results in inferior altitudinal hemianopia
- Following pars plana vitrectomy
