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85 Cards in this Set
- Front
- Back
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Which cells in the ocular dominance histogram are monocular?
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1 and 7
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Which eye does category 1 cells receive from?
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contralateral eye
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Which eye does category 7 cells receive input from?
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ipsilateral eye
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Which category is bincocular and receive equal input from both eyes?
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4
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Which categories are dominated by the contraleteral eye but also binocular?
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2 and 3
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which categories are dominated by the ipsilateral eye but also binocular?
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5 and 6
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The period wchi the visual system can be influenced by environmental manipulation
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critical or sensitive period
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What is the duration of the critical period?
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7 to 9 years of age w/ the first two being the most critical
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T/F ocular dominance columns are initially organized prior to and independent of visual experience
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True
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Congenitally blind individuals are better at localizing sounds than sighted people, why?
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increased cortical area devoted to auditory input
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reduction in vision secondary to monocular deprivation during the critical period
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amblyopia
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T/F amblyopia results from an abnormal eye
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False. it is due to abnormal cortical development
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What three factors diagnosis amblyopia?
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-monoc occlusion
-anisometropia -strabismus |
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What three factors can cause occlusion amblyopia?
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-monoc congenital cataract
-lid ptosis -patching b/c of a dz |
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conditon where the two eyes have unequal refractive errors
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anisometropia
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Anisometropic Amblyopia occurs most commonly with what 3 types of refractive errors?
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-conpound hyperopic anisometropia
-simple hyperopic anisometropia -antimetropia (myopic) |
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T/F the pt will have greatly reduced stereopsis with anisometropic amblyopia.
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True
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How could vision loss be helped in anisometropic amblyopic pts?
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-correction during the critical period
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anisometropia in which both eyes are myopic is referred to as ...
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compound myopic anisometropia
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T/F Amblyopia develops in constant unilateral deveiations more so than alternating or nonconstant deviations?
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True
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What is the predicted acuity and sterescopic vision in a person who has alternating amblyopia?
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-good vision
-little to no stereoscopic vision |
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what effect will strab pts not see?
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-the tilt aftereffect
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What is the tx for amblyopia?
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-patch the nonamblyopic eye
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T/F short periods of pathcing are as effective as longer periods for the tx of moderate amblyopia in children
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True, you would do this by use of a cycloplegic or patching
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occurs when a child progresses through the critical period with one visual meridian focused and the other out of focus
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-meridional amblyopia
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how much astigmatism do neonates usually manifest?
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0.75 to 2.00D
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Caucasian neonates are likely to show what type of astigmatism?
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ATR
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Chinese neonates are more likely to have type of astigmatism?
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WTR
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The amount of the astigmatism found in neonates generally decreases over what time?
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the first 5 to 6 years of life
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T/F It is generally not advisable to optically correct low to moderate amounts of astigmatism in infants
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True
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How much astigmatism should there be and what type before correcting it?
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At least 2.00 D and especially with ATR
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what common sx does ATR astig have?
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-Asthenopia (child will not want to read)
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T/F pts born with dense bilateral cataracts that are removed w/in the first 187 days of life appear to have permanently reduced ability to discriminate among similar faces, a task taht also apparently involves higher cortical areas
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True
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T/F Myopia parents are more liekly ot have myopic children
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True
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when do most growth of the eyeball occur?
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first 6 years of life
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suturing an animal's eyelid closed at birth or optically blurring the retinal image early in life leads to the development of axial myopia - this is evidence for what theory
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-environmental role in the development of myopia
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What type of refractive error are we born with?
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-slight amount of hyperopia (less than 2.50D) during the first year of life
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What is the resolution acuity of a 1 month old infant?
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20/600
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the optokinetic nystgmus response consist of which two movements?
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-slow following mvmt (smooth pursuits) folled by fast compensatory eye movement (saccade)
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OKN is useful in what type of pts?
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-infatns
-malingerers -hysterics -mentally retarded |
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T/F A pt could have impaired vision, yet show a normal OKN response
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True
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The behavrious whc infants prefer to view the patterned stimulus
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perferntial looking (PL)
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if the examiner is required to guess which side the pattern is on the procedure is called
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forced-choice preferential looking (FPL)
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what is the percentage correct that will elicit's the infant's grating acuity
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-75% correct
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T/F teller acuity cards have lower reliability
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true
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When are adult levels of 20/20 acuity reached?
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3 to 5 years of age
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what accounts for the porr acuity of infants?
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-immaturities in the retina, particularly the foveal cones
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FPL suggests that adults levels of resolution acuity are reached by what age?
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between 3 and 5
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VEP suggests that adult lvls of resolution acuity are reached by what age?
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6 to 8 months
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What is the difference in outcome of the FPL and VEP due to?
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-the greater cognitive demans associated wtih FPL
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CSF for 1 month old infants does not have a band-pass form. What does this suggest?
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-the lateral interconnections w/in the retina, which are responsible for lateral inhibition have not fully developed
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CSF is adult-like at what age
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-9 YO
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When does vernier acuity mature
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-matures rapidaly during the first year or so
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When does vernier acuity become adult like?
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6-8 years old
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Why does vernier acuity develop later in life?
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-slow maturation of the cortex
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When does stereoacuity mature?
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-6 mo. (1 min of arc)
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the retinal and cortical immaturities that slow the development of graing and vernier acuity have little effect on the (blank)
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-maturation of temporal resolution
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What is the critical flicker fusion frequency of a 1 mo. old
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40 Hz
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when is the scotopic sensitivity function adult like?
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1 mo. of age
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When does the scotopic sensitivty function b/c adult like at an early age?
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-it is det by the absorption characteristics of rhodopsin and does not depend on postreceptoral processing
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when tdoes the absolute sensitivty of the scoptopic system for a stimulus of 507nm develop?
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6 mo. of age
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Preferential viewing has been used to examin what color discrimination?
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-red-green and blue-yel
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when does rudimentary red-green discrimination arise?
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2nd mo of life
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T/F blue-yel discrimination has not been well understood
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True
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When are infants able to discriminate b/w two monkey faces?
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6 mo.
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CFF and the forms of the scoptopic and photopic sensitivy function show adult-liek characteristics w/in (blank)
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the first 6 months
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Grating and vernier acuity improve rapidly during the (blank), but then slowly mature until the child is (blank) and (blank)
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-first year
-3 to 5 -6 to 8 |
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T/F the critical period for the development of stereopsis may terminate at a younger age than the critical period for the development of vernier acuity
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True
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What tests can be use to examine the vision of children earlier on in life?
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-retinoscopy
-the cover and Hirshberg tests -opthalmoscopy |
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how does contrast sensitivy change as we age?
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remains constant until 65 YO and declines rapidly after that
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What contributes to reduced contrast senstivity?
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-nuclear sclerosis
-senile miosis -aging neural elements |
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What is the size of a pupil of a typical 20 YO?
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5.3 mm
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What is the typical size of a pupil in a 60 YO?
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3.2 mm
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how much light reaches the eye of a 60 YO?
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-one third of the retinal illumination of a 20 YO
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what is an adv of a sm pupil?
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increase depth of field
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yellowing of the crystalline lens is called a ...
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-nuclear sclerosis
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How does resolution acuity change as a person ages?
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-it is maintained till 65 to 70 YO
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T/F visual acuity measured under conditions of reduced contrast, reduced illumination, or added glare shows marked reductions in the elderly, especially in the very old
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True
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The tine it takes for visual acuity to recover following exposure to a birhgt light (disability glare recovery) also increase with age
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True
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Does the weber fraction change in the elderly?
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-no, b/c the senile miosis and nuclear sclerosis reduce the retinal illumination produced by the increment and background by the same amount
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How does standard visual field and UFV change as a person ages?
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-standard visual field does change
-UFV decreases, particularly beyond the age of 50 years |
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what color discrimination b/c increasing more difficult as an individual ages?
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blue-yel
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T/F sensitivity to temporal modulation decreases in the aging eye at all temporal frequencies
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True
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How does steropsis change in the elderly?
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b/c increasingly elevated beyond the age of 50 YO
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How does astimatism change in the elderly?
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increases in dioptric power in teh horizontal meridian relative to the vertical meridian .... shifts from WTR to ATR
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