Low vision assessment Flashcards
What needs to be done during a low vision assessment?
Goal setting (need assessment and history)
Measure visual function (VA/CS/VF)
Make sure correct rx used (refraction)
Determine helpful LV aids (establish magnification)
Onward referral if needed (ocular exam)
Formulate care plan (feedback to rehab team and client)
What additional general questions need to be asked during an LVA H&S?
Are they registered as SI or SSI?
Have they tried any adaptations like magnifiers, lighting or apps?
Do they have any current aids?
Are they aware of Access to Work? (if relevant)
Work out what their priorities are (and yours - may differ)
What should you ask in regards to mobility during an LVA?
How is getting around in familiar/new environments?
How did they get here?
What should you ask in regards to distance vision during an LVA?
Do they find it hard to see certain things (e.g. faces)?
Does the vision fluctuate?
Do they view eccentrically?
Is vision better in certain environments?
Any problems with glare?
What should you ask in regards to their living situation during an LVA?
Who do they live with?
Are they caring for someone else?
Any help, if alone?
How is getting around the house?
How is watching TV?
How is managing personal care?
Is seeing colour affected?
Any vision related falls in the last 12 months?
What should you ask in regards to near vision during an LVA?
How is reading?
Do you struggle with large print or own writing?
Is vision better in dim or bright light?
Can you still do your hobbies?
Why does VA need to be measured during a LVA?
Set a baseline
Understand px’s subjective impression of their vision
Early detection and diagnosis of disease
Monitor treatment
Allows prediction of visual function
Assess benefits of optical devices
Socio-legal purposes
Tell if needs updated refraction
What are the advantages of a Snellen chart?
Cheap
Common
Readily available
Sensitive to RE and blur
Can obtain baseline VA and predict/verify magnification needs for LV aids
What are the disadvantages of a Snellen chart?
No crowding control
Some letters easier to read than others
Letter progression isn’t uniform
Unable to score letter by letter accurately
Can’t accurately test LV pxs
What are the characteristics of the Bailey-Lovie chart?
5 letters on each line (evenly spaced)
Lines evenly spaced
1.25x size difference between rows
Size doubles every 3 rows
Can use at different distances
0.02 score for each letter
What are the advantages of the Bailey-Lovie chart?
Same no of letters on each line
Log progression of size
Can measure each letter
Robust scientific construction
Able to determine VA below 6/60
What are the disadvantages of the Bailey-Lovie chart?
Large
Expensive
No cross-cyl target
What are some other commonly used charts?
ETDRS
Keeler A Charts
Tumbling E
Landolt C
How should you determine refractive correction during a low vision assessment?
Ret - may need to work closer or work off axis
Use old specs as a guide
Use a trial frame with full aperture lenses (easier to work off axis)
Be careful with WD calculations
Use large brackets
Pinhole
Adjust DV for closer test chart if needed
What are some important things to remember about LV pxs?
An increase of at least two lines is needed for them to appreciate the difference subjectively.
If VA <6/60, rx change needs to be 1DS or 2DC to be significant.
Improvement with magnification will be more than VA improvement at distance.
Not all LV pxs will benefit from LVAs.
What are some ways you can test pxs with media and retinal loss subjectively?
Potential Acuity Meter
Laser inferometer
Vernier acuity
Photostress recovery time (differentiates macular and ON disease)
Glare testing (brightness acuity testing)
CV testing
Why should CS be measured in LV pxs?
Gives overall picture of visual function.
May indicate tasks that the px struggles with - better correlation than VA.
Helps to predict who won’t benefit from optical aids (low CS).
Can determine if mono or binoc LVA needed (due to visual function aspect).
What tests are available to check CS?
Hiding Heidi
VISTECH
Cambridge Gratings
Pelli-Robson
MARS
FACT
Reagan
Low contrast Bailey-Lovie
Arden
Lighthouse
Hamilton-Veale
Melbourne edge test
What distance should Pelli-Robson be performed at?
1m
How many log units is one triplet?
0.15 log units
What is the threshold on the Pelli-Robson?
Final triplet where 2/3 letters are read
What levels is CS loss categorised into on the Pelli-Robson?
Severe loss
Significant loss
Noticeable loss
Normal
How does the % of the Pelli-Robson change through the chart?
Halves every 2 triplets (go down vertically ~halves)
What are the advantages of the Pelli-Robson?
Easy to perform
Good repeatability and reliability
Better predictor of visual functioning than VA
