Exam 4 -- Extra-Striate Vision Flashcards
What is the average refractive error at age 2 years?
1.25
What age range is considered the critical period of visual development, during which time amblyopia can develop?
6 months to 2 years.
Which of the extra striate cortices is the end of the parvocellular stream?
V4
What is the average refractive error at age 6 months?
1.75
The Middle Temporal are (MT) is also known as?
V5
Balint Syndrome is a triad of findings. What three findings are they?
Simultagnosia, oculomotor ataxia, and oculomotor apraxia.
What are the three types of amblyopia? Which is most severe? Which is least severe?
Deprivational, strabismic, and refractive. Deprivational is most severe, refractive is least severe.
Which of the extra striate cortices is the end of the magnocellular stream?
V5
What is the average monocular VA at age 3 years?
20/30
What is the average refractive error at age 2.5 months?
2.5
List each of the stops that information from magno cells in the LGN passes through on its way to V5/MT.
- Layer 4C-alpha in V1
- Layer 4B in V1
- Thick dark stripes in V2
- V5/MT
How many categories of ocular dominance are there? Which category consists of ipsilateral-only input (in a binocularly normal patient)? Which consists of contralateral-only input?
7 categories. 7 is ipsilateral, 1 is contralateral.
True or false: a cortically-blind infant can have an optokinetic nystagmus.
True. The OKN is controlled by the cerebellum and the pretectum, not the cortex.
What would the cortical dominance histogram look like for a patient with alternating exotropia?
It would be skewed toward 1 and 7, with little to no input to the other columns (since there is never concurrent input by both eyes)
List each of the stops that information from parvo cells in the LGN passes through on its way to V4/IT.
- Layer 4C-beta in V1
- Blobs (for color), interblobs for detail (in V1)
- Blobs to thin dark stripes in V2; interblobs to pale stripes in V2
- V4/IT
What is the average monocular VA at age 6 months?
20/110
How would deprivational amblyopia affect the ocular dominance histogram?
The histogram would be skewed toward the eye without the deprivation (i.e., if a patient had a left congenital cataract, measuring the ocular dominance of the right striate would show skewing toward ipsilateral (7), while measuring the ocular dominance of the left striate would show skewing toward contralateral (1)).
Which of the extra striate cortices is for local motion (like pursuits)?
V3
Which of the extra striate cortices is for global motion (like saccades)?
V5