Visual Fields and Lesions

Question 1

What is bitemporal heteronymous hemianopsia?

Answer 1

Tunnel vision
Blindness on nasal half of retina or the temporal half of the visual field

Question 2

What is bitemporal heteronymous hemianopsia caused by?

Answer 2

Midline lesions of the optic chiasm
Interrupting decussating fibers of both eyes

Question 3

What is ipsilateral nasal hemianopsia?

Answer 3

Nasal visual field is lost on one side
Interruption of non-decussating fibers

Question 4

What is ipsilateral nasal hemianopsia caused by?

Answer 4

Possibly due to an aneurysm to the internal carotid
Something just affecting the lateral part of the pathway

Question 5

What is contralateral homonymous hemianopsia?

Answer 5

Blindness in the visual field contralateral to the lesion
Complete interruption of the optic tract, lateral geniculate body, optic radiations or visual cortex on one side

Question 6

What is contralateral lower quadrantic anopsia?

Answer 6

Interruption of the pathways from the ipsilateral upper temporal quadrant of the retina and the contralateral upper nasal quadrant of the retina
Two lower visual field quadrants are blind

Question 7

What is contralateral lower quadrantic anopsia caused from?

Answer 7

Lesions in the cuneus

Question 8

What is cortical blindness?

Answer 8

Light reflexes still in tact but the visual information never reaches V1

Question 9

What can cause cortical blindness?

Answer 9

Stroke, trauma, or loss of oxygen and blood to the striate cortex

Question 10

What supplies blood to V1?

Answer 10

Posterior cerebral artery, but the middle cerebral artery overlaps a little bit

Question 11

What happens if the calcarine artery is occluded?

Answer 11

There is a safety valve through the middle cerebral artery