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Disorders of the visual pathway

Last updated: February 2, 2021

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The visual pathway transmits signals from the retina to the visual cortex. It consists of the retina, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiations, and visual cortex. Lesions of the visual pathway may lead to visual disturbances or visual loss, the pattern of which can assist in determining the exact location of the lesion. Unilateral visual field loss indicates a prechiasmal pathology, while bilateral visual field loss indicates a chiasmal or retrochiasmal pathology. Retinal diseases mostly cause central or paracentral scotomas. Prechiasmal damage to the visual pathway usually involves the optic nerve (e.g., optic neuritis, optic atrophy, AION, papilledema) and may manifest with anopia or a centrocecal scotoma. Damage in the region of the optic chiasm is most commonly due to compression by a pituitary adenoma or craniopharyngioma and manifests with bitemporal heteronymous hemianopsia (lesions of the crossing fibers) or binasal hemianopsia (lesions of noncrossing fibers). Retrochiasmal visual pathway damage occurs in the region of the optic tract, lateral geniculate nucleus, optic radiation, or visual cortex and is most commonly due to cerebral ischemia/hemorrhage, tumors, or trauma. It usually manifests with homonymous hemianopsia or homonymous quadrantanopsia.

The visual pathways transmit signals from the retina to the visual cortex (striate cortex, brodmann area 17).

Structure Characteristics Lesions Causes
  • Cones and rods transform light into visual signals, which are projected to the brain via the optic nerve.
Optic nerve
Optic chiasm
  • Middle lesions (crossing fibers) → bitemporal heteronymous hemianopsia
  • Bilateral lesions (non-crossing fibers) → binasal hemianopsia
Optic tract

Lateral geniculate nucleus (LGN)

Optic radiations
Visual cortex

Unilateral visual field loss → pathology mainly in front of the optic chiasm. Bilateral visual field loss → pathology mainly in or behind the optic chiasm

Remember that the Meyer Loop transmits the signal from the Lower retina, Looping around the inferior horn of the Lateral ventricle.


Prechiasmal damage to the visual pathway mainly involves the optic nerve.For retinal diseases see table above.

Optic nerve

Optic neuritis

Multiple sclerosis is the most common cause of optic neuritis!

Optic atrophy

Anterior ischemic optic neuropathy (AION)

Immediate high-dose glucocorticoid treatment is essential in AAION!


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