Visual pathway or visual field deficits are defects in visual space determined by the location of a lesion in the neurological visual pathway from eye to brain cortex. Understanding of the visual system is paramount 1:
-
retina or optic nerve
- anopia or central scotoma (ipsilateral)
-
optic chiasm 2
- anterior (at the junction with one of the optic nerves)
- junctional scotoma (ipsilateral central scotoma with contralateral superotemporal/temporal field defect)
- middle
- bitemporal hemianopsia (central lesions involving crossing fibers; classic)
- binasal hemianopsia (bilateral lesions involving noncrossing fibers; rare 3)
- posterior (at the junction with one of the optic tracts)
- scotomatous bitemporal hemianopsia
- anterior (at the junction with one of the optic nerves)
-
optic tract
- homonymous hemianopsia
-
lateral geniculate nucleus
- homonymous sectoranopia or hemianopsia
-
temporal lobe
- homonymous upper quadrant defect ("pie in the sky" quadrantanopia)
-
parietal lobe
- homonymous defect, denser inferiorly (inferior quadrantanopia)
-
occipital lobe
- complete
- isolated homonymous defect (macular sparing)
- lower bank
- homonymous upper quadrantanopia with macular sparing
- upper bank
- homonymous lower quadrantanopia with macular sparing
- complete
Vison abnormalities other than visual field deficits can also help localize lesions 1:
- retina, optic nerve, optic chiasm, or contralateral optic tract
- relative afferent pupillary defect (Marcus-Gunn pupil)
- bilateral lesions
- occipital lobe
- Anton syndrome (cortical blindness)
- occipitoparietal
- occipitotemporal
- achromatopsia
- prosopagnosia
- occipital lobe
- left occipital lobe and angular gyrus
- alexia without agraphia
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