Testing visual function Flashcards
What do patients worry about when having a sight test?
Different environment
The tests that will be done
That we will find something wrong
That they’re wasting our time
Parents may worry about their child’s response
What counts as a successful sight test?
Patient and carer/parent is calm and willing to return
Some idea of px’s vision gained (some advice can be given)
What is resolution acuity?
Ability to resolve the difference between 2 targets
What is recognition acuity?
Being able to identify a target as well as seeing it
At what age would you usually use preferential looking (gratings)?
Under 12 months
How should preferential looking be performed?
Examiner shouldn’t know where the grating is - look through peephole to estimate response/present at eye level
If correct twice: assume they can see grating
Acuity = finest grating with repeatable positive result
What is the test distance for Teller cards? What units does it measure in?
38/55/84cm
Snellen (feet)
What is the test distance for Keeler cards? What units does it measure in?
38/55/84cm
LogMAR and Snellen
What is the test distance for the City-Cardiff test? What units does it measure in?
50cm
LogMAR and Snellen
What is the test distance for Lea Gratings Paddles? What units does it measure in?
57cm (may need to half or quarter distance for young children)
Cycles per cm
What age should preferential looking (pictures) be done?
12-36 months
What is the test distance for Cardiff cards? What units does it measure in?
50cm-1m
Snellen and LogMAR
What age should you use Kay pictures for?
> 2.5 years
What is the test distance for Kay pictures? What units does it measure in?
3m (calibrated for 6m)
Snellen and LogMAR
How can you use Kay pictures and Keeler LogMAR/Glasgow Acuity cards to measure VA?
Naming
Matching
Signing
What units does the Lea symbols chart measure in?
Snellen (both)
LogMAR
Decimal
What is the test distance for Keeler LogMAR/Glasgow Acuity cards? What units does it measure in?
3m (scored as 6m)
Snellen
When can you use Keeler LogMAR/Glasgow Acuity cards or the Kay Letter test?
When children know letters
When can you use the Snellen/Bailey-Lovie chart?
When children are confident with letters
What are some good methods to make sure children don’t get bored when measuring VA?
Occlude alternatively - allows binocular viewing between each presentation
Read half the line
Use frosted occluder - not as scary
Do CT at same time
Always end on a good note
What should you record for VA?
Test used
Distance
How well px responded
Which eye was tested first/if alternative occlusion used
Any relevant observations
What other methods are there for testing visual acuity?
Bradford Functional Vision Box
Hundreds and Thousands
If a child objects to occlusion what does that mean? What age does it normally happen from?
Better vision in the eye you’re trying to cover
3 months+
What are some ways of measuring near VA in children?
Reading books (e.g. Keeler)
Maclure (corresponds to American School Grades)
Kay Pictures Near
