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231 Cards in this Set
- Front
- Back
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Visuomotor mechanisms includes (5)
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1 saccade
2. pursuit 3. vestibular-controlled and optokinetic movement (VOR&OKN) 4. Vergence 5. Accommodation |
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Definition of saccade eye movement
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expand the visual field by shifting the eyes
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definition of smooth pursuit
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hold fixation on a moving object
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definition of vestibular-controlled and optokinetic movements
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stable fixation while the observer or visual field is moving
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definition of vergence
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allows the eyes to maintain alignment on objects at different viewing distances
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What does accommodation allow the eyes to do
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have sharp image on retina
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Approaches for infant eye movement research
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1. direct observation
2. corneal reflection trackers 3. electrooculogram (EOG) |
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what is the difference b/w direct observation to the other 2 methodology for infant eye movement research
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DO measure eye movement wrt to "HEAD POSITION"
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According to electrooculogram, what are the nature of charges of cornea and retina
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Cornea -positive
Retina-negative |
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Mechanism of corneal reflection tracter, what is the requirement
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-use IR to measure limbus and pupil margins
-child has to wear spectacle device |
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Fixation
-present at birth? -become accurate -clinical relevance |
-present at birth
-accurate by 6-9 wks -lack of fixation is a warning sign of visual impairment |
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If the child doesn't have accurate fixation by 6-9 weeks, what can it imply
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cortical visual impairment (permanent)
delayed visual maturation ( normal by age 1) |
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Eye alignment
-present at birth? -time of accuracy -chilical relevance |
-rudimentary binocular alignment (brief period up to 6 mos)
-6 months -pseudostrabismus, infantile ET |
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what is the possible explanation for the rudimentary binocular alignment from birth to 6 monthes
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attention state,
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what is the max onset of age to DX infantile ET
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6 months old
(if the infant is born with ET = congenital ET) |
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Saccade (adult)
-form -speed -latency -accuracy -fashion of movement |
-form: conjugate
-speed: rapid (800 deg/s) -latency: short (200 ms) -accuracy: 10% undershoot error in the first saccade -fashion of movement: ballistic (unchanged) |
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Saccade (infant)
-form -speed -latency -accuracy -fashion of movement |
-form: ?
-speed? -latency: 5x longer -accuracy: need multiple saccades -fashion of movement: catch up saccade |
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Smooth pursuit (adult)
-speed -latency |
-speed: as low as 0.08 deg/s
as fast as 40 deg/s -latency: 1/8 s (125ms) |
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T/F
In adult, pursuit has shorter latency than saccade |
True
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Smooth pursuit (infant)
-speed (constant velocity target vs pendular target) -latency |
Constant moving target = <15 deg (by 6 wk) ; >15 deg (by 12 wk)
Pendular target = can't follow, track w/ saccade (< 2m) ; true pursuit (by 2-3 m) |
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Smooth pursuit (infant)
-present at birth? -time of accuracy -clinical impact |
- possible present at birth with slow, large targe ; fast target: use saccade for tracking
-2~3 mon -nystagmus (acquired/congenital |
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Nystagmus
-OU or monocular impairment -onset -type (2) |
-OU "central" visual impairment
-b4 2 yr -Acquired (onset w/in 1 m of vision loss) -Congenital (onset w/in 2-3 mon of age) |
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T/F
Nystagmus is a sign that early vision loss occurred |
TRUE
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Congenital nystagmus
-onset -association |
-2~3 mon
- 3A's (amaurosis, albinism, achromatopsia) ; ON atrophy, hypoplasia, CSNB |
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what is " optokinetic eye movement" (OKN)
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involuntary following eye movements
(slow following, saccade back) |
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Purpose of OKN
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minimize motion of the moving environment up the retina
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OKN (infant)
-present at birth? -time of accuracy -clinical impact |
-present at birth, but < 3 mon, asymmety (poor N --> T)
-Symmetry ( > 5mon) ~stereopsis -asymmetry during first year caused by strabismus, cataract, amblyopia) |
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Symmetric OKN is reached by what age
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5 months
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which systemc is required to have nasalward OKN movement
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subcortical
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Signal to the nasal retinal project to which side of NOT and causes what eye movement
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nasal retina --> contralateral NOT --> nasal movement
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Vestbulo-ocular Reflex (VOR) is
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"Involuntary", "Conjugate" eye movement
-eye mv response to head acceleration -slow pursuit in opposite to head movement, interrupted by fast saccade. |
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during head movement, how does the eyes move
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head moves --> eye slowly turn the OPPOSITE to the head mv (head turns right, eyes turn left) . the slow opposite mv is interrupted by VOR
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Purpose of VOR
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stablize retinal image
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Doll's head maneuver
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method to test VOR
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VOR
-present at birth -accuracy -Clinical impact |
-present at birth
- can't suppress VOR till 2 mon -inability to suppress VOR in blind infants |
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Vergence depends on (4) factors
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1. tonic innervation to EOM
2. accommodation 3. perceived distance 4. retinal disparity |
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Vergence (infant)
-present at birth? -time of accuracy -clinical impact |
-birth: ortho, poor, slow vergence
-adult like: 3 mon |
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Convergence
-target distance -time of adult like -fusion reflex response by -fusion vergence by -clinical impact |
-distance > 10 inch
-3 mon -fusion reflex: 6 mon -fusion vergence: 6 mon -small strabismus or amblyopia |
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Accommodation
-present at birth? -time of accuracy -adult level when - |
-present at birth, but not accurate
-by 3 month -adult level = 5 month |
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What factor contributes to the improvement of accommodative accuracy
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reduce depth of focus
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2 factors contribute to poor accommodative accuracy
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drowsiness
large depth of focus |
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Accommodation
-present at birth? -time of accuracy -adult level -clinical impact |
-yes, but not accurate
-3 month -adult level: 5 month -discrepancies in prevalence of RE for cycloplegic vs non-cycloplegic |
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Eye movement present from birth (7), may not act accurately
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fixation
VOR OKN rudimentary binocular alighment saccade pursuit |
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T/F
normal eye movements do NOT develop in visually imparied infants |
TRUE
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Assessment of visual function in fants
-qualitative |
face
complex patterns |
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Assessment of visual function in infants
-quantitative |
preferential looking
visual evoked potential optokinetic nystagmus |
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Earliest PL procedure for acuity assessment
- target -# of target -# different spatial freqnency -# of target presented each time -record of |
-grating w/ homogenous background
-10 pairs -5 frequency -twice each time -duration of looking and # of fixations of each stimulus |
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Result of earlier PL procedure
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infants prefer over the grating with homogenous field
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Limitations of early PL procedure
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1. it's a group data, can't determine the level of vision of an individual infant
2. subjective nature of observer's task |
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Forced choice PL procedure
-is a method of.............stimuli |
constant stimuli
(there ls " level expectation") starts off from 50% |
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Forced choice PL, VA is at what %
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75%
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Forced choice PL
-Strength |
little observer bias
individual VA estimate |
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Forced choise PL
-Weakness |
time consuming (15 min)
not useful in clinical setting |
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Operant FPL
-special feature |
Motivation for looking
(baby gets awards) |
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Acuity card procedure
-tests on (2) -# presentation |
quality and consistency of looking
-wide stripe (x2) -fine stripe (several times) |
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Acuity card procedure
-location of acuity card - |
50 cm
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Normative binocular PL acuity procedures include
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method of constant stimuli
staircase procedure acuity card procedure |
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Mean interocular acuity differences for normal infants tested with PL procedures
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IOD <1 octave (3 lines of log MAR)
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post natal =
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# month after birthdate
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post term =
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# month after being full term
(usually a smaller number than post-natal) |
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Premies show delayed acuity development if we plot VA by what age
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postnatal
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Clinical applications of acuity card procedure
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for delayed visual maturation infants
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Overall evaluation of PL testing
-strength -LIMITATION |
-S: non-invasive
easily performed inexpensive applicable to clinic populations (nystagmus pt) -L: accurate to only (+/- 3 lines in log MAR) test-retest variability observer bias grating acuity is not the same as Snellen acuity |
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Visual evoked potential
-electrical signal is measured on which cerebral lobe -test reflects activity of |
1. occipital lobe
2. post synaptic potential |
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Variables in stimuli that influence VEP waveform
(3) |
1. pattern vs luminance
2. presentation mode 3. temporal frequency (transient/steady-state) |
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Transient temporal frequency (cy/s)
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< 4 c/s
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Visual acuity by VEP is by looking at VEP's......?
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VEP amplitude determines the VA
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VEP shows
1. relationship w/ spatial frequency 2. adult-like by what age |
1. VEP decreases linearly with increase spatial frequency
2. 6 month |
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VEP amplitude: normal vs. amblyopic eye
Compared (VEP amplitudes to grating) and (VEP amplitude to luminance) b/w amblyopic and normal eyes |
Amblyopic eye:
Normal --> luminance Reduced --> grating |
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T/F
Retina is the locus for amblyopia? |
FALSE
cortical is the locus!! |
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Spatial frequency sweet Vep Procedure
-duration -# of different frequencies -acuity determined by |
-10 s / trial
-19 -linear extrapolation of VEP amplitude to zero microv |
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Spatial frequency sweep VEP
-Advantage |
-increased sampling can avoid overestimate and underestimate
-repeated meastures -clinical applicability |
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Normal acuity development according to Sweep VEP
-at birth -8 month |
birth: 4.5 c/d (20/130)
8 month: 20 c/d (20/30) |
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Clinical application of sweeP VEP
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amblyopia
media opacity cortical visual impairment |
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Does visual experience improves acuity? VEP measured in premature infants
post natal vs post-conceptual |
PL acuity in premature infants is predictable from "post-term(post-conceptual)
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which term infants show higher acuity during the first few months of life
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pr-term
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Definition of "Pre-term"
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born early by 1<x<3 weeks
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Definition of "Post-term"
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born late
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T/F
pre-term baby has higher VEP acuity than post-term baby, they reach the same level by 5 month |
TRUE
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Evaluation of VEP testing
-strength -limitation |
-S:fast test
no subjective bias applicable to many clinic populations mean test-retest variablity and IOD (<0.25 octave) high grating acuity norm -L: expense personnel expertise doesn't tell what pt sees hazards of converting |
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VEP vs PL
Advantage |
VEP: objective test
expect better acuity smaller IOD and standard dev PL: portability easy to use accessibility |
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VEP vs PL
Disadvantage |
VEP: expensive
requires technician grating acuity measure PL: requires cooperation observer bias limited durability of cards grating acuity measure |
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FPL vs VEP
-discrepancy comes from the difference in visual stimuli? |
Probably not
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Discrepancy FPL vs VEP comes from the difference in scoring techniques?
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PL critia: 75 % correct
VEP criteria: 0 uv Conclusion: does not account for all of the difference |
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T/F
VEP, PL, OKN yield different acuity b/c hey tap different visual mechanisms |
TRUE
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VEP tests what visual mechanism
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early cortical processing
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FPL tap what visual mechanisms
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later stages of visual processing
attention motion control |
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Types of visual acuity (5)
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detection
resolution isolated identification crowded identification hyperacuity (Vernier) |
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Resolution
-testing for -factors -minimal |
-minimal resolvable
-optical limitation of the eye photoreceptor spacing min: 0.5~1' apart |
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Detection
-testing for -minimal |
-minimal visible
-0.5' detail |
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Isolated identification
-testing for -minimal |
-minimum recognizable
-0.5' = 20/15 1.0' = 20/20 |
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Crowded identification
-test for -minimal |
-minimum recognizable with hirizontal contour interaction
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Hyperacuity (Vernier)
-testing for -minimal |
-minimum discriminable
-3~6' offsets |
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FPL Vernier acuity
-limitation based on age -at 10 wk -at 12 wk -conclusion |
-not reliably measurable b4 10 weeks
-10wk - 2000 sec -12 wk -1000 sec -conclusion: Vernier acuity develops rapidly, it has a different developmental time course than grating acuity |
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Grating acuity vs Vernier acuity
-adult level -which one develops faster |
-VEP= 6 mo
FPL= ? VVA=? Conclusion: -VVA develops in parallel to resolution acuity b/w birth~6 mon; initially worse, then improves b/w 2~8 mon; -VVA takes longer > RA -VVA continues to develop up to age 20; not RA |
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Contrst sensitivity
-threshold -equation |
-lowest contrast detectable for a given size stimulus
-C= (Lmax-Lmin) / (Lmax+Lmin) -CS = 1/contrast threshold |
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Contrast sensitivity
-high frequency roll off due to |
optical blur
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Hyperacuity (Vernier)
-testing for -minimal |
-minimum discriminable
-3~6' offsets |
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FPL Vernier acuity
-limitation based on age -at 10 wk -at 12 wk -conclusion |
-not reliably measurable b4 10 weeks
-10wk - 2000 sec -12 wk -1000 sec -conclusion: Vernier acuity develops rapidly, it has a different developmental time course than grating acuity |
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Grating acuity vs Vernier acuity
-adult level -which one develops faster |
-VEP= 6 mo
FPL= ? VVA=? Conclusion: -VVA develops in parallel to resolution acuity b/w birth~6 mon; initially worse, then improves b/w 2~8 mon; -VVA takes longer > RA -VVA continues to develop up to age 20; not RA |
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Contrst sensitivity
-threshold -equation |
-lowest contrast detectable for a given size stimulus
-C= (Lmax-Lmin) / (Lmax+Lmin) -CS = 1/contrast threshold |
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Contrast sensitivity
-high frequency roll off due to |
optical blur
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Contrast sensitivity
-low frequency roll off |
lateral inhibition
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Importance of contrast sensitivity
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Low to Mid range spatial frequency are important for facial recognition, recognition of real world target, and mobility
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With age,PL contrast sensitivity and scale both improve, what does it mean
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improved sensitivity = visual system can process targets more efficiently
improved in scale= visual system is better at spatial filtering With age, we are better at detecingt contrast and we can detect higher frequency |
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before what age is the low frequency not observed in human infant
why is that |
<1 month
mechanism for lateral inhibition not mature |
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Infant Sweep VEP contrast sensitivity
-VA= |
7.6 cpd
increase the contrast will increase the VEP amplitude |
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CS development of improved sensitivity and higher frequency are due to factors of
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-sensitivity: photoreceptor maturation
-frequency: cone packing density, cones become thinner in fovea |
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CS reaches adult level by what age
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3 months
but continues to develop 6+ mon |
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Limitations of the infant eye on vision
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optics
pupil accommodation (altered by alertness) foveal cones |
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Clinical measures of spatial vision (2)
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visual acuity-see fine details
contrast sensitivity-see shades of grey |
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Visual acuity is the ability to see fine details
-very sensitive to (2) |
blur
visual degradation |
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Contrast sensitivity is the ability to see shades of gray
-not sensitive to |
visual degradation, or amblyogenic factors
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Contrast sensitivity test on infants(3)
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sweet VEP
Mr. Happy (15 cards) Hiding Heidi` |
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Temporal vision maturation (CFF)
-by 1 mon -by 3 month |
-1 mon = 40 Hz
-3 mon = 50 hz |
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T/F
Infants prefer flicker over steady light |
TRUE
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Which develops faster, temporal vision vs spatial vision?
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Temporal vision
(M matures earlier than P) |
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Amblyopia prevalence in US
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3%
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Amblyopia is the leading cause of what in 20-70 year olds
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monocular vision loss
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T/F
Amblyopia is always associated with a history of early sensory anomaly |
TRUE
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The assoicated factors with amblyopia (5)
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anisometropia
strabismus astigmastism high hyperopia form deprivation |
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The highest associated factor with amblyopia is..............
what % |
50% of amblyopia is caused by anisometropia
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% of amblyopia is assicoated with strabismus AND aniso
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27%
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% of amblyopia is assicoated with strabismus alone
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15 %
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% of amblyopia is assicoated with visual deprivation
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4%
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What is the VA in the weaker eye compared to the non-amblyopic eye
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20/40 worse (2 lines different)
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Amblyopic VA must be measured by what design
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"recognition" task
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VA performance in amblyopia(5)
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-wide range of acuity errors: miss some large one and read some smaller ones
-missed letters are not similar in shapes -read letters out of order -read better with end-of-row letters -abnormal head position |
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T/F
Amblyopic vision is indistinct |
true
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T/F
Amblyopic vision can be improved by pinhole |
FALSE
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Crowding effect is more pronounced in which type of amblyopia
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strabismus amblyopia
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patching the preferred eye is more bothersome in which type of amblyopia
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strabismus amblyopia
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Characteristics of amblyopic eye (3)
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spatial uncertainty
spatial distortion VA worse by at least 2 lines |
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Spatial uncertainty is more pronounced in which type of amblyopia
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strabismus amblyopia
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Anisometropic amblyopia shows only what
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spatial uncertainty (lesser degree)
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Strabismus amblyopia shows
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spatial uncertainty AND distortion
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S-chart: range of VA testing
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20/9~20/277
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Snellen vs Grating Acuity vs Vernier in amblyopia
-Aniso -Strabismus |
Aniso: all thress are linearly related
Strabismus: Snellen and Vernier are linearly related (1:4) ; Snellen worse than grating |
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Development of Vernier and grating acuity in normal eye
-by 6 m -by 4 y -adult |
-6 mon: 2:1
-4 y: 4:1 -adult: 10:1 |
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Does strabismus amblyopia ever develop the normal b/w Vernier and grating acuity?
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NEVER
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CSF in amblyopia
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CSF function distribution shape similar in both amblyopic and normal eyes
Entire function is shifted down in amblyopia |
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Visograms
-purpose -flatter visogram means |
- tell how big the discrepancy is b/w the normal and amblyopic eyes
-higher acuity = flatter |
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Based on Visograms, what is the CS level between (aniso+stra) vs (strab) vs (aniso)
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VA is better:
(aniso+stra) > strabismus > aniso |
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Reduced CS is more pronounce at what spatial frequency
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high
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Magnitude of loss CS at low sf depends on
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size of the stimulus filled
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Reduced CSF reflects a neural loss in
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foveal function
(p/w from retina to brain) |
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Fixational eye movements in amblyopia (amplitude&frequency)
-micro tremor -drift -saccade |
-micro tremor: normal both
-drift: normal amplitude but more nasal drift; often no on fovea -saccades: normal in velocity&frequency, amplitude not normal (larger with worse VA) |
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Accommodation in amblyopia
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reduced acc response in amblyopic eye
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Abnormal ocular motility in amblyopia (4)
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fixation
saccade&pursuit OKN accommodation |
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Amblyopic visual system resembles the immature visual system in (3) terms
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1. normal in low spatial frequency
2. reduced spatial vision (lower CS,Vernier) 3. reduced ocular motility (acc, fix, sac, pur, OKN) |
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Abnormal visual development in abmlyopia due to (2)
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arrest
extinction |
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What does arrest mean in amblylopia
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sensory obstacle "arrests" the development of acuity, it "freezes" the development at that point
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What does "extinction" mean in amblyopia
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suppression extincts amblyopia
(patching can rid extinction, but VA stays in arrest level) |
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Amblyopia can be caused by form deprivation such as
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congenital cataract
"unilateral" ptosis corneal opacity tumors occlusion |
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T/F
Unilateral form deprivation is worse than bilateral |
TRUE
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Intervention of uni/bi lateral congenital cataract
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surgery + good patching
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Depth of amblyopia in Unilateral cataract depends on
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1. age of begin
2. length of present time **** 3. age of removal 4. time b/w aphakia and optical correction 5. presence of strabismus The earlier, the longer the unilateral cataract exists, the worse! |
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Classification of strabismus based on (5)
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direction
magnitude laterality (uni vs alternating) frequency comitance |
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Infantile ET
-onset -prevalence -large deviation -laterality -prognosis |
-onset: <6 m (not at birth)
-2% (account for 50% of all ET*****) -large deviation (30~120pd) -alternating ET (40% leads to amblyopia) -poor if Tx after 2y |
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Microtropia
-definition |
microstrabismus
monofixation syndrome |
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Microtropia
-magnitude -mechanism -signs -prognosis |
-1~9 pd
-often post-surgical ET/VT residual tropl aniso w/ ET -shallow amblyopic, poor stereopsis, central suppression, peripheral fusion -poor for bifoveal fixation, stable end-stage condition |
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Eficacy of tx for strabismic amblyopia
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If the onset for infantile ET is <3 mon, better tx early
If the onset of ET happens > 2 y age, tx outcome is good even if it's delayed tx for adult (age 18-22), workable, but need to be aggressive |
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Concern for tx for amblyopia
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etiology
depth age accommpanying RE accompanying disorders |
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Fail to tx amblyopia and strabismus can lead to
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IRREVERSIBLE visual deficit
permanent amblyopia loss of depth perception loss of binocularity cosmetic defects educational/occupational restrictions |
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Requirement of good corresponding binocular vision (4)
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-good VA, OU
-good ocular motility -good stereopsis -good connection b/w sensory and motor systems |
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Is depth perception innate or learned
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not born with
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Limitation of visual cliff experiment to influence the outcome can be
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no eye exam first
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Monocular depth cues (10)
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perspective
relative size/height distance fog texture gradient depth from focus occlusion color vision shadow motion paralax |
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Binocular depth cues
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-developed later
-convergence, stereopsis |
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most precise cue to depth depends on
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retinal disparity
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crossed disparity for object closer/further from the fixation point
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closer
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Development of stereopsis measured by PL
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developed suddenly ~4m
reach adult level (1 minarc) w/in few wks crossed disparity develops first near cells mature first |
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Clinical tests for stereopsis
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1. colored filter (TNO)
2. polaroid filters ( stereosmile, randot, titmus) 3. real depth separation (frisby) 4. prism separation (lang) |
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Pros of polaroid filter stereopsis test
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stereopsis must rely on binocular cues, monocular cues don't work.
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If a child has good stereopsis, what does it mean
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child has good VA, OU and rule out constant strabismus
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FPL and VEP agree on the development of stereopsis
-age of onset |
3.5 mon~6 mon
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T/F
Pt don't need accurate vergence control in order to have good stereopsis |
TRUE
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Misalignment of infant's eyes proceed to 6 mons, but infants don't see diplopia, why?
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1. panum's fusional area (15minarc of adult, infant's is larger)
2. fovea immaturity |
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T/F
VA is not the primary limiting factor in the rapid onset of stereopsis |
true
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If VA is not the limiting factor of stereopsis, what is
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segregation of ocular dominance columns
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segregation of ocular dominance columns occur at what cortical layer
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layer IV
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Post-stereoptic periods
-VA -Pupil size |
1. VA better in OU
2. Smaller pupil in OU |
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Pre-stereoptic vs Post-steropotic periods
-VA -Pupil size |
Pre-stereopsis:
VA and pupil sizes appear no difference either in OU or monocular. |
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Before stereopsis, infants prefer which type of pattern
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the one shows rivalry or fusion
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T/F
Avoidance of rivalry in post-stereopic infants |
TRUE
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Age of binocular vision development
1. binocular fusion 2. disparity detection 3. stereopsis |
1. BF: 3 mon
2. DD: 3 mon 3. Stereopsis: 4 mon (60s)-VEP&FPL 6 mon (< 1 minarc) |
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Clinical impact of lack of stereopsis
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possible amblyopia / strabismus
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is surgery necessary for intermittent infantile ET before 3 months of age?
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no, it tends to go away
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Stereopsis in infantile ET
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- w/o intervention, disappear p 4 mon.
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Stereoacuity > 400s
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= has peripheral binocularity
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Stereoacuity 80~200
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macular binocularity
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Stereoacuity <60 s
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foveal binocularity
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Logical order for BV development
-at birth |
1. poor grating acuity
2. ortho or tiny misalignment (more E) 3.some binocular corrdination |
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Logical order for BV development
-birth~3 mon |
1. grating acuity improves
2. OU fixation together 3. segregation of near.far cells in cortical layer IV. |
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Logical order for BV development
-3~6 months |
1. dramatic alternations in visual cortex
2. rapid increase in stereoscopic acuity 3. full convergenceEM, orthoT 4. binocular summation and rivalry |
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Logical order for BV development
6+ month |
1. grating acuity improves
2. stereoscopic acuity reaches 1 minarc |
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Symmary of Stereopsis development
-present at birth? -onset -limiting factor |
- not at birth,
-rapid onset at 3~5 months, crossed disparity develops faster - cortical development |
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Vision disorder that compromise stereopsis
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monocular VA loss = amblyopia
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How does absolute thresholds measured in infant
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Forced choice PL in dark adapted infants. Large stimuli <1s duration presented to L/R. Observer reports the finding.
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Result of FPL in absolute thresholds in infant
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threshold decreases rapidly w/ age ( lower the threshold, more sensitive)
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Compare absolute threshold in infant vs adult
-4 w -10 w -18 w -6 mo |
-4 w: 1.5 log unit higher
-10 w: 1 log unit higher -18 w: 2/3 log unit higher -6 mon: adult level |
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Def of absolute threshold
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constant over a large range of stimulus areas.
when infant reaches their threshold, the critical area is LARGER than adults |
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Spatial summation areas
-small stmuli meets what law |
Ricco's law
= for small stimuli, threshold is inversely proportional to stimulus area |
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Spatial summation areas
-larger stimuli |
Ricco's law NOT hold.
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Increment threshold functions is rod/cone mediated?
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ROD
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T/F
Both increment threshold functions and intensity functions of infant are similar in "shape" to adults |
True
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Increment threshold functions in infant
-highest threshold occur at ?age -with age? |
-highest threshold at 4 wks
-threshold decreases with age |
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Weber fraction delta L/L =
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slope =1
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Infant reaches Weber's law by what age
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2-4 mons
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Indication of shallow Weber's slope
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rod-cone interactions are immature or absence
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T/F
Weber fraction decreases at the same rate as absolute threshold (by 6 mon) |
True
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Absolute thresholds
-age of adult level |
6 m
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is spatial summation area the same in infant as in adult?
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NO,
infant of (4-11wk) has larger area |
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Increment threshold functions
-adult level -obey weber's law |
-2~4 mon
-yes by 2-4 m |
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Color vision development test
-procedure |
-FPL
-present each color test simulus at different luminances -if infant looks at the colored one of equal luminance background, infant has color vision |
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Color vision development
-Dichromatic (tritanopic) by age |
10 wk
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Tritan means
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Failed in zone centered in Y/G + mid purples
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protanopia and deuteranopia
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R/G blindness
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T/F
Trichomat hasn't developed by 10 wks of age |
TRUE
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Developmental age by VEP and FPL
1. functional MWS&LWS cones and post-receptor circuits 2. functional SWS cones |
1. TWO wk (VEP) vs 10 wk (FPL)
2. Five weeks (VEP) vs 3 mon (FPL) * rods and at least one cone type are functional by 1 m (FPL) |
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Prevalence of X-linked R/G color defect
-male -female |
-male = 10%
-female = 0.5% |
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Prevalence of autosomal dominant tritan
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0.0015 ~ 0.007%
( 10~70 / 1 million) |
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Prevalence of achomatopsia
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0.003%
(30/ 1 million) |
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T/F
CVD father can't make kids have CVD, but will make his daughter carriers |
TRUE
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T/F
All color vision defects come from the father side? |
FALSE!
Mother's side!!! |
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Time frame for development of various visual attributes
2~4 mons 30~60 month 60~128 month |
1. luminous efficiency, dark adaptation, absolute threshold, peak of contrast sensitivity
2. grating acuity 3. Vernier acuity |
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T/F
CVD children report difficulty in seeing traffic lights at night time more often than in day time |
FALSE
day time is more difficult (decreased contrast) |
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Infant color vision development
-absolute threshold |
6 mon
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Infant color vision development
-spatial summation areas |
larger in (4~11 wk) infant
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Infant color vision development
-Increment threshold functions -adult like? -Weber's law? |
Similar to adults
obey Weber's law by 4 mon |
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Infant color vision development
-color vision: *Rod + 1 cone *Dichromatic(tritanopic) *trichromatic |
1 mon
2 mon 3 mon |
