Intro/ Development Flashcards
vision testing requirements in CA
- VA upon first enrollment and every 3 years thereafter
- Color vision for boys only upon entry into the first grade
what are the AOA guidelines for ages for eye exams?
- by 6 months
- at 3 years
- before 1st grade and every 2 years thereafter
what % of children receive an eye exam before 5 years of age?
14%
prevalence of amblyopia
2-3%
what ethnic group has a higher prevalence of ambylopia
hispanic/latino
prevalence of strabismus
3-4%
prevalence of refractive error
15-30%
prevalence of ocular disease
< 1%
prevalence of color vision defects
8-10%
what anatomy contributes to young children not being able to see 20/20?
- immature cones (short and stumpy)
- fovea is last area of retina to develop morphologically
- immature visual cortex
- incomplete myelination
the VEP method of measuring VA shows what patterns of VA
1mo: 5cpd (20/120)
2. 5mo: 7.8cpd (20/77)
6mo: 18cpd (20/33)
12mo: 25cpd (20/24)
about how long does it take for a child to reach 20/20 when measuring VA with preferential looking?
can be up until 3/4 years to see 20/20
requires more cooperation/attention from the child
when does contrast sensitivity reach adult like levels?
6-10 years
what is unique about accommodation for an infant?
- variable within 1-3 months
- infants have a large depth of focus
when does accommodation reach adult like levels for low demands?
~ 3-4 months
but longer latency than adults
what is the VOR reflex?
vestibulo-ocular reflex: connection between inner ear to EOMs to maintain fixation with head movement changes
what are saccades like in infants
- present at birth
- long latency, wrong direction, short amplitude
is stereopsis present at birth?
no
when is the onset of stereopsis and when is development spurt?
starts at 3-5 months
-development spurt between 4-6 months
when does stereopsis reach adult like levels
~ 2 years old
300 sec of arc
when is the “critical period” for binocular development
up to 3 years old
when is the “sensitive period” for binocular development
up to 10 years old
is binocular fixation and convergence present at birth?
yes
most infants are orthotropic at ___ month(s)
1 month
when do infants gain fusion
3-4 months
when do infants’ binocular fixation and convergence become adult-like
6-7 months
what are some conditions that prevent development of the cortical circuits underlying stereoscopic vision (causing amblyopia)
- congenital cataracts
- esotropia
- anisometropia
what is unique about the anatomy in the newborn eyes
- shorter eyeball
- really steep cornea
- really powerful lens
what changes in the eyes anatomy from newborn to 3-9 months
- cornea loses power
- lose power in lens
- eyeball gets longer
the binocular visual field of normal 6 to 7 month old infants was ___% that of the adults
93 %
when does color vision emerge
1-3 months
VEP studies show what emergence for color vision for the different wavelengths
2 weeks: long and medium wavelengths
5 weeks: short wavelengths
when is color vision adult like
3-4 months
