At what age can you start using VEP?
1 month
Infants reach VA of 20/20 w/ VEP at what age?
6 months
VEP
provide info about the integrity of the pathway of the visual system
- does NOT provide info about the ability to perceive a visual stimuli
Subjective methods show VA 20/20 by what age? (ex. snellen, forced-choice method)
3-4yo
Most common subjective method used for infants?
forced choice preferential looking (FCPL)
Teller acuity
based on FCPL and widely used in pediatric clinics for infants up to 12 months
Examples of FCPL
broken wheel, teller acuity cards, cardiff
What’s the threshold of teller acuity cards?
75%
approximate spatial visual acuity using FCPL methods for:
1 month of age
1 yo
3-4 yo
1 month = 20/600 - 20/1200
1 year = 20/50-20/60
3-4 years = 20/20
OKN drum
Children will have asymmetric OKN until what age? Why?
3-5 yo due to incomplete development of the cortex
Normal vs abnormal OKN response
TONS = NORMAL
Temporal to Nasal
The other way is abnormal (Nasal to temporal)
positive vs negative OKN response
(+) = pt can see stripes
(-) = pt cannot see stripes or not paying attention
Vernier acuity (aka hyperacuity)
ability to detect misalignment of 2 lines
- develops slowly and worse than spatial acuity until 4 months of age
Vernier acuity reaches adult levels at what age?
6-8 years
Recognition acuity develops at what age?
the ability to detect optotypes
2-3 yo
Examples of recognition acuity
Allen pictures
American Optical pictures
HOTV chart
Lea symbols
Landolt C chart
Tumbling E chart
Snellen chart may be used at the beginning of what age?
2 yo or older may respond to the snellen chart
Why is VA poor until the age of 3-5 yo?
Lenght and density of cone reaches adult level at what age?
4 years old
Infants will not have a bright foveal reflex until what age?
15 months
Myelineation is complete at what age?
2 years
The visual cortex reaches adult level at what age?
6 months
Avg refractive error for a full term newborn?
+2.00D