Measuring Visual Acuity (M1) Flashcards
How many letters per line are there for a LogMAR chart? 1. What is each letter “worth”? 2
- 5
2. 0.02
What is the gold standard for VA for children? 1. What are the test distances used for this? 2. What is it measured in? 3. Is this a 2AFC test or a preferential looking test? 4
- Teller visual acuity
- 38, 55, 84cm (55 mostly)
- cpd (not Snellen)
- preferential looking test
What is the type of measurement that shows the ability to resolve a critical element of a stimulus or pattern?
resolution acuity
Which protocol for amblyopia visual acuity assessment is used for children under 7? 1. Older than 7? 2
- ATS HOTV protocol
2. E-ETDRS protocol
What is the test of visual ability where a large bright object is moved slowly 1-2 feet from the patient? 1. How is it recorded? 2
- Fix and follow
- “F&F” = normal; “CSM” = not normal; central (C) or eccentric (UC); steady (S) or poor (US); Maintained fixation (M) or unmaintained (UM)
Since the optokinetic nystagmus test involves motion, what type of vision may still respond? 1. How would you be able to tell the Snellen acuity? 2
- poor central vision
2. vary test distance
What is the type of measurement that shows if the eye has the ability to see but does not quantify it?
visual ability
During the 10 pd Base Up Test what should be asked of the patient? 1. What should be looked for by the examiner? 2
- ask if see two targets
2. look for eye behind prism to saccade down to find the target. Test both eyes
What is the problem with the American Optical Picture Chart?
unequal blur, luminance and size
What type of acuity are the Lea Symbols measuring? 1. What are the options for administration? 2. What are the units used? 3
- recognition acuity
- naming, matching, 2AFC
- logMAR
What are the major preferential looking tests?
- Teller VA
- Patti stripes
- Lea gratings
- Richmond face dot paddles
What is the test that looks at how the patient reacts differently when covering one of their eyes than the other? 1. How is it recorded? 2
- resistance to occlusion
2. No RTO, equal RTO or RTO OD/OS
What is the type of measurement that shows the ability to identify a particular symbol?
recognition acuity
Why is measuring the visual acuity of a child important?
- medicolegal reasons (establish VA before manipulate)
- monitor disease progress
- understand level of visual ability
What is the difference between the Lea Symbols and Patti Pics?
have a 5th optotype
If you double the distance, how many lines worse should VA be?
3 lines worse
What is done to find the MAR for VA?
inverse of Snellen and divide (20/100 = 5 min arc)
For the decimal notation of a VA what is done?
divide Snellen fraction (20/100 = 0.2)
How many cycles per degree are in 1 min of arc (20/20)?
30
What type of test is the Sjogren hand test/ tumbling E/ Landolt C? 1. Why is this a poor test in preschoolers? 2
- resolution acuity
2. requires laterality and directionality development
When is resolution acuity present? 1. When is it mature? 2.
- birth
2. 3 to 6 months
Which resolution acuity test uses a vanishing optotype paradigm with more interesting targets than gratings? 1. What is this test especially useful for? 2
- Cardiff cards
2. determine VA on pt’s with congenital nystagmus
Which test is just like the Landolt C but takes away the concept of directionality? 1. Is this a 2AFC test or a preferential looking test? 2
- Broken wheel
2. 2AFC
What type of acuity are the HOTV charts measuring? 1. What are the options for administration? 2. What are the units used? 3. What makes it more difficult than Lea? 4
- recognition acuity
- naming or matching
- logMAR
- letters harder than pictures
