Visual Fields Flashcards
What parts of the brain are involved in visual processing?
Posterior parietal: “where”
Inferior temporal: “what”
PFC
What are the neurons of the primary visual system?
Bipolar neurons (retina) -> RGC -> optic nerve to LGN -> geniculocalcarine tract to V1/area 17 calcarine fissure (lingula, cuneus)
What are the 3 coats of the eye?
Outer fibrous (sclera, cornea), middle vascular (iris, ciliary body, choroid), inner (retina pig epi and neural retina)
Where do the looping and non-looping fibers project?
Looping: lower bank of calcarine fissure (lingula)
Non: upper bank (cuneus)
Where is macular vision represented on the cortex?
Posterior ⅓ primary visual cortex
What is anopia? scotoma?
Large visual field deficit; small deficit
What is a homonymous visual field deficit? heteronymous?
Homo: same visual field deficit for each eye
Hetero: different visual field deficit for each eye
What is hemianopia? Quadrantanopia?
½ visual field deficit; ¼ field deficit
What would a lesion to R looping fibers cause?
Left superior homonymous quadrantanopia
How do deficits differ with lesions anterior to chiasm, at chiasm (crossing fibers), and posterior to chiasm?
Ant: ipsilateral eye only
At: bitemporal heteronymous deficit
Post: contralateral homonymous
What pathologies could cause bitemporal heteronymous hemianopia?
Pituitary tumor or anterior communicating artery aneurysm
What is the blood supply to the optic radiations? What visual deficit would appear with infarction?
MCA; contralateral homonymous deficits, may be partial sparing
What is the blood supply to primary visual cortex? What visual deficit would appear with infarction?
PCA; contralateral homonymous hemianopia
Which vessels does CN3 travel between?
PCA and superior cerebellar a
What two arteries place the optic chiasm at risk?
Internal carotid (side -> ipsilateral nasal deficit) and anterior communicating a from above (crossing fiber erosion -> bitemporal heteronymous hemianopia)
