Test 1 things I can't remember Flashcards
4 types of acuity
Detection/minimum visible
Resolution/minimum seperable
Vernier
Recognition
Visual acuity testing limits
Cognitive
Boredom
Cortical immaturities
Foveal cone immaturities- short, stubby, spread out. (Full development at 4 years)
Foveal pit immaturities (development at 17 mos)
Examples of resolution VA testing
TAC, Lea paddles. Subjective. Must pay attention to where child looks.
TAC ranges
20/400 to 20/10 (but not really equal to snellen)
Visual acuity FPL norms of development
- Steady increase from when to when?
- Adult levels by what age?
Steady increase from 4 weeks to 1 year. Adult levels by 3-3-5 years.
FLP VA 1-2 months 4 months 6 months 9 months
1-2 months 20/400
4 months 20/200
6 months 20/150
9 months 20/50
Lea gratings distance
TAC distance
Lea: 57cm
TAC: 55
OKN Is induced by
Speed of motion of the visual field. Holds image stable on retina with head/world movement
Is OKN foveal/affected by blur?
Not foveal, not affected by blur. Can get positive response with high refractive error.
No OKN response could indicate
Lesions in OKN cortex, cerebellum, brain stem
Dysmorphia
Cortical blindness
5 methods to test VA in an infant/non-verbal child
CSM F&F TAC Lea paddles OKN
What does the VEP look at?
Wiring from the central retina to the primary visual cortex.
Looks at macular function and makes sure the visual system is in tact.
Unlike FPL, cannot determine perception of what the child sees, just that they can see at all.
3 types of VEP displays
- Pattern reverse- detects minor pathway abnormalities.
- Sweep- clinician can see where good response drops off.
- Flash
VEP and binocular summation
Should be at least 10% more than either OD or OS.
If it is lower than the dominant eye then interference may be going on. need to get tx for baby.
cardiff cards test disc
1 meter or 50 cm
What kind of acuity tests are preferred for pre school acuity?
Letter tests. Should be able to ID letters by age of kindergarten. ( age 5)
What VA test does not go down to 20/20?
Allen. pictures do not blur equally, may over estimate VA
Tumbling E horizontal responses are not consistent until
Age 8
Average VA test for age: Infant/non verbal Toddler Preschooler School age
Infant/non verbal: CSM, F&F, TAC, Lea paddles, OKN
Toddler: Cardiff
Preschooler: HOTV, lea symbols, cardiff
School age: Snellen
4 types of binocular vision tests
Alignment
Motility
Sensory fusion- stereo
Motor fusion- everything else
At what age should you expect alignment, convergence, and stereo to improve? Expect eyes to be straight
12 weeks/3 month
Angle kappa results
+ kappa = nasal reflex = temporal fovea
- kappa = temporal reflex = nasal fovea
Between visual axis (FNF) and pupillary axis (tangential to cornea, through the ent pupil)
Hirschberg results
Nasal + exo
Temporal - eso
Krimsky
Hirschberg + prism
Bruckner
Use DO 1 meter away from patient.
Look at hirschberg and size/color/brightness of pupils.
Convergence development
1 months can converge
consistent at 2 months
without delay at 3 months
Stereo development emerges when?
3-4 months
By age 6, all infants appreciate stereo.