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
The Medial Superior Temporal area (MST) is also known as?
V3
Development of contrast sensitivity, vernier acuity, and grating acuity takes place beginning around what age?
Over 32 months
Which of the extra striate cortices is for color and facial/object recognition?
V4
Which of the extra striate cortices is for binocular vision?
V2
Changes in a series of pictures are harder to see when they are presented side-by-side, but are easier to see when presented sequentially. Which retinal cell helps to spot the changes with sequential viewing?
Amacrine.
The Inferior Temporal area (IT) is also known as?
V4
Hemispatial neglect is usually caused by a lesion in which area of the brain, on which side?
Inferior parietal lobe, right side (so left visual field affected).
What is the average monocular VA at age 2 years?
20/60
Development of stereopsis, scotopic sensitivity, photopic/scotopic luminosity, and CFF takes place around what age?
2 months to around 6 months
Blindsight is when a patient is blind but can accurately point to the location of a visual stimulus or report the direction of motion. What is the classic explanation for the location of damage that causes blindsight? Where does the damage more likely occur?
Classic explanation is superior colliculus; reality is probably damage to V1 that leaves spared “islands”.
Dominance slabs and edge detectors are found in which areas?
V1 and V2
Name some of the causes of Balint Syndrome.
CJD, perinatal hypoxia, nitroglycerin, Alzheimer’s disease
True or false: the limits of contrast sensitivity before age 1 year is due to immaturities in the cortex.
False; the limitation is due to immaturities in the retina, not the cortex.
What is the average monocular VA at age 2.5 months?
20/280
Damage to which area is thought to cause apperceptive agnosia?
Right parietal lobe.
What is the average monocular VA at age 1 month?
20/640
What is the human peak of contrast sensitivity, both in cpd and Snellen equivalent? By what age is this peak present?
Peak is 4 cpd (20/150 Snellen). This peak is present by age 4 years.
Between apperceptive and associative agnosia, which is more severe?
Apperceptive.
Damage to which area is thought to cause associative agnosia?
Left temporal-occipital junction.
Cortical blindness is the loss of vision in V1 despite intact eyes, optic nerves, and optic radiations. What is the name of the condition if patients are unaware of their blindness? What are some causes of cortical blindness?
Anton Syndrome. Cortical blindness can be caused by birth defects, trauma, Creutzfeld-Jakob Disease, and epilepsy meds.
What is the average refractive error at age 1 year?
1.5
What is the average refractive error at age 3 years?
1
True or false: R/G color vision development starts around age 2 and may continue until adolescence.
True.
True or false: the diameter of the visual field changes little with age, but decreases dramatically with age with split attention.
True.
Forced preferential looking is a way to measure a child’s acuity using grating patterns. What percent of correct performance indicates the level of the child’s VA?
75%
What is the average monocular VA at age 1 year?
20/90
What is the average refractive error at age 4 years?
1.25
At what age is contrast sensitivity up to adult-like levels?
9 years
What is the average monocular VA at age 4 years?
20/20
