Visual
fields, by Nancy Newman
Horizontal
respect
in retinal
ganglion cells, respect horizontal raphe, send bundles into optic nerve in that
fashion
If no
respect for vertical, have to be in front of the chiasm
Central
scotoma, within 20 degrees
Centrocecal,
central and blind spot
Paracentral,
outside of 20 degrees
Arcuate
Bjerrum
scotoma - glc, optic neuritis
altitudinal
defect - glc, ischemic neuropathy, branch artery occulision, hydroplastic nerve
central
scotomas - optic neuritis, maculopathy
centrocecaldefects
- toxic and deficiency neuropathies
nasal
defects - glc, chronic papilledema, drusen
altitudinal
- defects confined to the upper or lower half of the field
homonymous -
defects in the fields of both eeyes and on the same side of midline
congruous -
homonymous defects identical in the two eyes
retrochiasmal
lesions are homonymous
tract:
non-congruous if partial; optic atrophy
geniculate:
non-congruous;optic atrophy
temporal:
non-congrous, superior
parietal:
congruous, inferior
occipital:
congruous, may spare fixation, may be scotomatous; temporal crescent
the more
posterior, the more congruous
1 eye or 2?
does it
respect the vertical?
is it
homonomous? if not, likely at chiasm
parietal is
superior
temporal is
inferior
most central
portion of visual field is most posterior portion of occipital cortex
middle
cerebral supply to occipital lobe - feeds medial portion of that lobe
if infarct
PCA, can have macular sparing because it is supplied by MCA
occipital
lobe - temporal crescent, congruous homonymous scotomas, complete hemianopia
with sparing of fixation
lateral
geniculate - homonymous "innie" defect (posterior choroidal artery)
and "outie" (defect anterior
choroidal artery)
if no
respect for horizontal, can be RP, glc, or constricting papilledema (but should
have nasal step) - retinal degenerations
respects
horizontal and vertical, congruous, is occipital lobe infarct
temporal
crescent sparing - spare most anterior portion of calcuran cortex
if complete
congruous homonymous anopsia, cannot say more than behind chiasm on one side