Visual Acuities Flashcards
4 testing methods for VA
minimum visible/detection acuity
minimum separable/ resolution
Vernier acuity (don’t use clinically)
Recognition acuity (snellen)
Detection acuity
Child states whether or not an object is present.
Similar to visual field. Can you detect the stimulus or not?
Not used much
Ex: Can you find the blue jellybean at different distances?
Problem: Not standardized. Hard to document/repeat/compare.
Resolution acuity stimuli
Square wave, sine wave, checkerboard.
Can use with children or non-verbal pts.
Vernier Acuity
The smallest area of misalignment that can be detected between two stimuli. Not used clinically, more experimental.
Could be two lines or two dots
Recognition acuity- landolt C
Child chooses between two images- one with broken C and one with circle. Forced preferential pattern.
Most common recognition acuity test
Snellen
Differences in cortical immaturities in children
Incomplete myelination of optic pathways
Limits of acuity testing in children. Why might they not have as good of vision?
Incomplete myelination Foveal and cone immaturities -Short and stubby (4 yrs) -Less densely packed (3-4 years) Variable morphology of foveal pit
When does the foveal pit become more adult like?
17 months.
Foveal and cone immaturities in children
Short and stubby til age 4
less densely packed til age 4
Full development of foveal cone in children
4 years
If you cannot get monocular acuities, then what?
Test binocular but do other objective tests to assess: Ret, CT, health check
How to occlude babies eye?
Sticky patch, mom/dads hand.
What is more concerning?
Baby cries when OD and OS are covered
Baby cries when OD is covered, ok when OS is covered
Asymmetry is concerning.
Baby who cries about both eyes could mean they just don’t like eye being covered.
What do infants love to look at?
Faces
Babies should be able to make eye contact at ___ weeks
8
Babies should smile back at you at __ weeks
12
Heidi smile test
Screening device. 3 months. Not acuity test!
CSM technique and what are you assessing?
Central, steady, maintained.
Use penlight and shine into pt’s monocular eye.
Gross assessment of fixation and acuity. Used by many peds ophthalmologists.
What does CSM stand for?
Central:
Light is centered on pupil
Steady:
Eye is steady, no nystagmus
Maintained:
Can the eye follow a target? Ex: follow the pen light. Indicates acuity