Highlighted content chapter 11 Flashcards
Highlighted and underlined content
A tumor on the what part of the brain can press on the optic chiasm?
Pituitary
A tumor on the pituitary can press on the optic chiasm and cause what kind of field defects?
Bilateral temporal (aka bitemporal hemianopia)
How would you describe the orientation of the image on the retina?
Inverted and reversed
Information from the lower visual field is projected on the ___________ retina
upper
Why are images reversed on the retina?
The right visual field projects onto the left retina (and vice versa) of each eye
Why are images inverted on the retina?
Information from the upper visual field is projected onto the lower retina, and vice versa
The central fixation point for each eye is what?
The fovea
Where do fibers that carry visual information cross?
Optic chiasm
True or false: There is a total crossing of fibers in the optic chiasm
False; it’s a partial crossing of fibers
Lesions anterior to the [optic] chiasm produce what kind of visual field defects?
monocular
Lesions of the optic chiasm produce what kind of visual field defects?
bilateral lateral
The medial (nasal) fibers from both eyes do what in the optic chiasm?
Cross over
The optic tract wraps around the midbrain, then to where?
The lateral geniculate nuclei (LGN) of the thalamus
Where does the optic tract go after the optic chiasm?
The LGN of the thalamus
What can result in bitemporal hemianopia from compression of the optic chiasm?
Pituitary adenomas
Why do pituitary adenomas cause the visual effect they do?
They press on the optic chiasm, compressing the medial fibers, which convey the outer half of vision for both eyes
What is the superior colliculus important in?
Directing visual attention and eye movements towards visual stimuli
1) The superior colliculus and pretectal areas project where for visual attention?
2) How?
1) To the brainstem and association cortex
2) Via relays in other thalamic nuclei
What are the functions of the other thalamic nuclei that project the superior colliculus to the brainstem?
Visual attention/orientation/discrimination/perception (i.e. help us direct our attention to something seen or heard)
What do the neurons of the LGN do?
Participate in motion, spatial awareness, and color vision.
What fans out over a wide area to form the optic radiations?
The superior colliculi
What pathway is likely defective if color vision isn’t working?
The LGN
Central __________________ occlusion can cause infarction of the entire retina
retinal artery
Define Amaurosis Fugax
Transient occlusion of the retinal artery
1) What causes Amaurosis Fugax?
2) What is a common cause of that?
1) Emboli [occluding the retinal artery]
2) Ipsilateral carotid artery stenosis
If a patient describes having the visual of a window shade going up or down in one eye, what might they be having?
Amaurosis Fugax
What are the two main symptoms of Amaurosis Fugax?
1) A “window shade going up or down” on ONE eye
2) Loss of vision in one eye for roughly 10 min.
What can Amaurosis Fugax be a signal of?
Impending retinal or cerebral infarct.
1) What is optic neuritis?
2) What does it cause?
1) A demyelinating disorder of the optic nerve related to MS
2) Eye pain with movement (among other things) of one eye
_____ or more of patients with a clinically isolated episode of optic neuritis will eventually develop MS
50%
If a patient complains of pain in one eye that’s worse with movement, what may they have?
Optic neuritis
