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Disorders of the visual pathway

Last updated: July 13, 2020

Overview

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

Structure Characteristics Lesions Causes
Retina
  • 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.

References:[1][2]

Prechiasmal visual pathway damage

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!

Papilledema

Damage in the region of the optic chiasm

Retrochiasmal visual pathway damage

References

  1. Wallace DJ. Antimalarial Drugs in the Treatment of Rheumatic Disease. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/antimalarial-drugs-in-the-treatment-of-rheumatic-disease.Last updated: October 23, 2017. Accessed: November 8, 2018.
  2. Luco C, Hoppe A, Schweitzer M, Vicuña X, Fantin A. Visual field defects in vascular lesions of the lateral geniculate body. J Neurol Neurosurg Psychiatry. 1992; 55 (1): p.12-5.