Vision Development Flashcards
Although VEP provides information about the integrity of the pathway of the visual system, will results always provide information regarding the infant’s ability to perceive a visual stimulus?
NO
Subjective methods of VA that require visual processing by the infant do not show 20/20 VA levels until 3-4 years of age
When does VEP reach 20/20 for infants?
6 months of age
When is forced choice preferential looking (FCPL), specifically Teller acuity cards, used in pediatric clinics?
Infants up to 12 months of age
When is FCPL methods approxminately 20/600 to 20/1200?
1 month of age
When is FCPL methods approximately 20/50 to 20/60?
1 years of age
When does spatial acuity reach 20/20?
3-4 years of age
When do infants have an asymmetric OKN?
Up until 3-5 months of age due to incomplete development of the cortex
What does a normal OKN response look like?
Temporal to nasal
Is a (-) OKN response conlusive?
NO
The infant may just not be paying attention (ONK requires attention and accommodation to the OKN drum)
When does vernier acuity develop?
Worse than spatial acuity until 4 months of age!
Rapidly develops beyond this point until adulthood
Adult levels by 6-8 years old
When does recognition acuity develop? EXAMPLES: Allen pictures, american optical pictures, HOTV, Lea symbols, Landolt C chart, tumbling E chart
~2 to 3 months of age
NOTE: pictures are often better than letters to resolve
Why is VA poor in infants until 3-5 years of age?
- Foveal cone PR are shorter and wider in infants vs adults (adult like by 4 years of age)
- Myelination of visual pathways is incomplete (adult: 4-6 months of age and not complete until 2 years of age)
- Visual cortex not fully developed in infants (adult like: 6 months of age, but develops well into childhood)
When will a bright foveal reflex develop?
~15 months of age
What is the average refraction for a newborn?
+2.00D (+/- 0.75D)
What is the average axial length for full term newborns?
16 mm
Adult: 24 mm
What is the mean refractive error at 10 weeks of age?
+4.00D
Reaches plano to +3.00D by 20 weeks
What is the mean refractive error approximately 1 year of age?
+0.50 to +1.00D & remains stable until the teen years
When does emmetropization not occur?
For extreme newborn RE (>+5.00/-4.50D)
What % of school children remain hyperopic?
80-85%
6% of 6 year olds become myopic and 15% of 15 year olds become myopic
Premature infants younger than what age usually have high myopia, high astigmatism, or high anisometropia at birth?
<37 weeks
Do premature infants have normal emmetropization with similar levels of hyperopia and astigmatism by 12 months compared to full term infants?
Yes!
Approx how many infants are born with astigmatism?
50%
What is the average amount of ATR astig at 6 months of age?
2.00D!
When does astigmatism reduce to about 0.50 or less in infants?
by 2 years of age
When does accommodation reach adult-like levels?
3-4 months of age
Why are infants able to have imprecise accommodation for a given distance without significantly impairing VA?
They have a very large depth of focus!
When can infants make divergent eye movements?
1 month
When does consistent convergent eye movements occur?
2 months
When does vergence eye movements become adult-like and are initiated by disparity?
6 months
When is accommodation and convergence linked?*
After 2 months of age when convergence matures.
When do pursuits become normal?
4 months of age
When does stereopsis reach adult levels?
4-6 months of age
Nearly 100% of infants have stereopsis by which age?
7 months
When does stereopsis reach adult levels of 1’?
24 months (2 years old)
NOTE: 2 years old is when astigmatism is reduced to 0.50 or less and when myelination is complete
True or False. The immaturity of eye movements that are necessary for bifoveal fixation is what limits sensory fusion and stereopsis before the age of 3 months
FALSE.
Immaturity of the visual cortex is thought to be the limiting factor to sensory fusion & stereopsis before 3 months of age
When does the ability to discriminate all hues from achromatic stimuli reach adult levels?
By 3-4 months of age
When does the scotopic sensitivity curve in infants reach adult levels?
4-7 months
