VA Continued

Question 1

What is a VEP?

Answer 1

visual evoked potentials, looks at the wiring from the central retina to the primary visual cortex

Question 2

What does VEP not measure?

Answer 2

the perception of what the child is seeing

Question 3

When do you do a VEP?

Answer 3

in a patient where VA is unable to be obtained (attention or poor responses) or a patient with possible pathology (not obvious)

Question 4

What are the VEPs from most preferred to least?

Answer 4

patterned reversed, sweep, flash

Question 5

What is the patterned reversed VEP?

Answer 5

1st choice, black and white alternating stripes or checkerboard squares, detect minor visual pathway abnormalities

Question 6

What is the sweep VEP?

Answer 6

black and white alternating stripes or checkerboard squares, pattern size/contrast levels change rapidly, clinician can see where good response drops off to determine VA

Question 7

What is the best VEP for poor attention?

Answer 7

sweep, only need attention for a few seconds

Question 8

What is flash VEP?

Answer 8

20 degrees, less than 5 ms

Question 9

T/F checkerboard with more, smaller squares correlates to better VA

Answer 9

true

Question 10

What is the VEP test distance?

Answer 10

50-150 cm depending on the size of the pattern

Question 11

What are binocular v monocular considerations for VEP?

Answer 11

binocular summation should be at least 10% more than either OD or OS, if lower than the dominant eye, then interference may be going on and treatment is more critical

Question 12

What are additional VEP considerations?

Answer 12

attention of patient, placement of electrode, 10% of adult levels at 6 months of age, 200% better than FPL

Question 13

How to read a pattern reversal VEP

Answer 13

amplitude: N75 to P100 // implicit time (latency) time from stimulus to largest amplitude wave

Question 14

What is a normal implicit time/latency?

Answer 14

85-120 ms for p wave

Question 15

What is a Cardiff card?

Answer 15

vanishing optotype with different pictures and vertical presentation

Question 16

What ages are Cardiff cards good for?

Answer 16

12-36 months aka 1-3 years

Question 17

What is the Cardiff card test distance?

Answer 17

1m or 50 cm

Question 18

How does the Cardiff card work?

Answer 18

child will look at the picture over the gray background if they can see it, child could also name the picture

Question 19

Is the Cardiff card tested monocularly or binocularly?

Answer 19

monocularly if able, otherwise bino

Question 20

What range of VAs do the Cardiff cards have?

Answer 20

20/160- 20/12.5

Question 21

What are the approximate Cardiff card age VAs?

Answer 21

1 year- 20/50+, 1.5 to 2 years- 20/25+, 3 years 20/20-20/40

Question 22

What are preschool acuity considerations?

Answer 22

letter tests are preferred, don’t assume the child knows letters

Question 23

When should a child ID letters?

Answer 23

end of kindergarten

Question 24

What are questions to ask yourself about preschool VAs?

Answer 24

Does the child have poor vision? know the letters? understand the task? bored?

Question 25

How do you occlude for preschool acuity?

Answer 25

pirate patch (fun!), sticky patch, check for peeking, posture squinting

Question 26

What are Allen pictures?

Answer 26

recognition acuity, pictures (car, phone, bird, cake, hand), child needs to name the pictures

Question 27

What are criticisms of Allen pictures?

Answer 27

dated, pictures do not blur equally, overestimate the VA, does not go to 20/20

Question 28

What is the tumbling E?

Answer 28

need to identify the direction of the letter E (up, right, left, down)

Question 29

What are criticisms of Tumbling E?

Answer 29

directional confusion until 8 yo, up down easier than L/R

Question 30

What are Lea Symbols/HOTV?

Answer 30

apple, house, circle and square, does not have directional confusion

Question 31

What is the procedure for Lea symbols?

Answer 31

whole line if child is able (4-5 years), can use matching card, if unable to do the whole line the crowding bars make it more difficult

Question 32

Why use crowding bars with Lea symbols?

Answer 32

more difficult for amblyopia because they see the 1st and last letters correctly but others hard

Question 33

What did the HOTV preschool acuity study show?

Answer 33

under 3 VA 20/63+, 3-4 yrs 20/50+, 4-5 yrs 20/40, 5-6 yrs 20/32+

Question 34

What did the HOTV preschool acuity study show in terms of IOD?

Answer 34

only 6% of normal had intraocular difference of 2+ lines between the eyes

Question 35

Order of preferred tests in clinic…

Answer 35

pick age/cognitive ability appropriate tests, snellen, lea/hotv, cardiff, FPM (teller or lea paddles)

Question 36

What age should be able to do one line snellen acuity?

Answer 36

kindergarten

Question 37

What age should be able to do a whole line Lea/HOTV?

Answer 37

around 4 years

Question 38

What age should be able to do blocked lea/hotv?

Answer 38

around 3 years, or do matching, single letter may overestimate

Question 39

What are the two last choice acuities clinically?

Answer 39

cardiff then FPL like teller or lea

Question 40

What VA test does a school aged child do?

Answer 40

snellen

Question 41

What VA test does a preschooler do?

Answer 41

HOTV, Lea, cardiff

Question 42

What VA test does a toddler or nonverbal patient do?

Answer 42

cardiff

Question 43

What VA test does an infant or nonverbal patient do?

Answer 43

TAC/Lea gratings, CSM, F&F, VEP