The optic chiasm
χίασμα, "crossing", from the Greek χλαζειν 'to mark with an X', after the Greek letter 'Χ
) is the part of the brain
where the optic nerves
Specifically, in the optic chiasm, the nerves connected to the right eye that attend to the right temporal visual field (located in the right retina) cross to the left half of the brain, while the nerves from the left eye that attend to the left temporal visual field (located in the left retina) cross to the right half of the brain.
This allows for parts of both eyes that attend to the right visual field to be processed in the left visual system in the brain, and vice versa.
Optic chiasm in cats
In Siamese cats
with certain genotypes
of the albino
gene, this wiring is disrupted, with less of the nerve-crossing than is normal, as a number of scholars have reported. To compensate for lack of crossing in their brains, they cross their eyes (strabismus
This is also seen in albino tigers, as Guillery & Kaas report.