Optic tract. Chiasm, optic tract, retrogeniculate pathways

The visual syndromes of chiasm lesions, of the optic tract and geniculate nucleus and the optic radiations until the occipital visual areas and their main etiologies are reviewed. Bitemporal hemianopsia and junction syndrome are the chiasmatic syndrome manifestations, commonly caused by hypophyseal compression lesions. Optic tract and geniculate ganglion lesions are rare and cause hemianopsias that may be very incongruent. In unilateral lesion on the retrochiasmal level, the visual defects only affect one hemifield without visual acuity deficit. Total or partial hemianopsia due to optic radiation lesion constitute the most frequent campimetric deficit in neurology, caused by vascular lesions and less frequently by expansive hemispheric lesions. Macular sparing in a hemianopsia is characteristic of the posterior cerebral artery infarction. Pursuit eye movement abnormalities and consequent asymmetry of the optokinetic nystag-mus accompany the hemianopsias due to temporo-parietal lesions. Parieto-temporo-occipital lesions cause agnostic manifestations that accompany campimetric defects.