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39 Cards in this Set
- Front
- Back
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Visual acuity is a
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Measure of sensitivity of spatial discrimination
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Acuity increases by about
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1 cycle per degree per month until 20 months of age
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The critical period for normal visual development is
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Before 6-8 months of age
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The limitation to early acuity is the
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Nervous system’s ability to process the image
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VA obtained with VEP is similar to adults by
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6-8 months of age
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Loss of sensitivity at low spatial frequencies indicates
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The working of lateral inhibition (noticed at 2 mo)
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The high frequency cut off changes from
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2cpd at 2mo to 20cpd at 10mo
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The lowest sensitivity to low spatial frequency is seen
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Between ages 8-15
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Avg refractive error in premature infants is
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+0.50D SD 2.80D
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Ave refractive error in full-term infants is
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+2.00D SD 2.00D
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1yr old RE =
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+1.00 SD 1.1D
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3yr old RE =
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+0.95 SD 1.00
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By 5 mo of age infants develop an
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Adult sensitivity curve to different wavelengths of light
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Brunescence of the lens causes the absorbance of
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Short (blue) wavelengths of light
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Accommodation if well developed by
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4 mo of age
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Lid closure in response to bright light is seen at
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30 weeks gestation
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The blink response to visual threat is seen at
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2-5 mo of age
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Infants have 1 min of stereopsis (60sec) by
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21 weeks (~5 mo)
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Saccades are present at birth and fully developed by
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4-5 mo of age (step saccades present before 4 mo)
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Infants use smooth pursuits for low velocities by
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2 mo of age
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OKN is seen at birth
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At 5-6 wks of age tracking is completed by
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Saccadic movements, not pursuits
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OKN is
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- smooth pursuit with a saccadic refixation in the opposite direction
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Monocular OKN is observed at
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3 months of age
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An asymmetric OKN is seen with
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Temporal to nasal mvnts of a stimulus (seen under 3 mo)
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The vestibular sense isn’t fully developed until
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4-5 years of age (child uses vision to stand upright)
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Conjugate horizontal gaze is well developed at
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Birth
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Conjugate vertical gaze is well developed at
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2 mo of age
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Papillary light reaction is present at
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31 wks (~6mo)
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The critical period for the development of ocular dominance columns is
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Between 6-8mo and 2.5 yrs in humans; 6wks in monkeys; 1-3 mo in kittens
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Deprivation experiments show
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No effect on the retina; Shrinkage of cells in all layers of the LGN; visual cortex is severely affected; alteration of ocular dominance columns occurs
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Pattern deprivation causes more disturbance of
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Binocularity than light deprivation
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The number of binocular cells decreases from
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80% to 20% in a stabismic animal
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Contrast sensitivity decreased with age
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Important for contact lens wearers
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Macular degeneration and nuclear sclerosis cause
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A loss in discrimination of the blue end of the spectrum
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Convergence ability stays the same or better with age
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Because accommodative convergence can be used
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The time to rod cone break
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Remains constant as one ages
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Senile miosis accounts for a
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7 cycle per second decrease in CFF by age 40yrs
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The most widespread of the psychoses is
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Schizophrenia
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