Visual pathway and physiological basis of visual field defects
7 min read
Definition
The visual pathway carries impulses from the retina through the optic nerve, chiasm, optic tract and lateral geniculate body (LGB) to the primary visual cortex (V1).
At the chiasm the two retinal halves behave differently:
Nasal fibers decussate to the opposite optic tract.
Temporal fibers stay uncrossed.
So each tract represents the contralateral visual field, the basis of the classic field defects.