Assessment of Vision in Infants & Children Flashcards
When are vision levels about normal from in children?
- Vision levels in children are initially poor at birth but rapidly increase over first few years of life
o About normal from about 5 years of age - Range of vision – not every child will see the same
o Depends on many factors – e.g. not developing normally, ability to sit for tests
What are the normal values for vision in children? 18-23 motnhs, 24-29 motnhs, 30-36 months?
18-23mths –> 0.6-0.1, 6/24-6/7.5
24-29mths –> 0.4-0.1, 6/15-6/7.5
30-36mths –> 0.3-0.1, 6/12-6/6
Describe Qualitative Assessment in children?
- Useful in v young or uncooperative pxs
- Estimation of VA – objective
o Can overestimate vision as they can see something but you don’t know what they’re seeing as they cannot tell you - Based on pxs reactions
o How does child react when you cover up a certain eye? - Compare behaviour of the 2 eyes
- Records the minimal visible versus the minimal separable in quantitative testing
- Tests:
o Assessment of fixation:
Can give lots of info
How well child can fix on something
How well they can hold fixation – do they follow it around – are they happy to do that – do they do that up close and when far away
Babies like lights so can use that – look for equal corneal reflections – are they looking with both eyes? - Held at 33cm
- 5cm toy – brightly coloured – animal that they like – lights up and makes noise – Kay Pictures, Amazon, Tiger
Also useful when child is old enough to do forced choice but uncooperative - By 6weeks of age babies should be able to fix and follow – lights or faces etc
Optokinetic Nystagmus (OKN) Drum: - Easy to perform – another thing to try if running out of ideas
- Provides qualitative info – similar to fix & follow methods
- Stripes move across field of vision – create an eye movement
- Px fixates on one stripe & then a quick movement in opposite direction
- Drum is rotated vertically in front of infant & response is observed
- Child on parent knee
- Rotate drum – stripes moving vertically
- See if child interacts with stripes and follows them as they move
o If child can see them they will follow them
o Will get back and forth movement if child can see it & follow it
Reaching out for objects – you know they can see it if they reach
Hundreds & thousands - ~6/24 if they can pick it up
Describe Quantitative Assessment in children?
- Precise measurement of VA
- Requires px to identify the minimal separable
- logMAR, Cardiff cards – gold standard eye test – to get accurate level of vision
- Tests:
o Forced Choice Preferential Looking (GCPL) – youngest babies
o Cardiff Acuity Cards
o Kays Picture Test – useful in children who don’t quite know letters
o logMAR
o Sonsken - Less Commonly Used Tests:
o Lea Symbols, Sheridan-Gardiner Test, Landolt C, Tumbling E
Describe assessment of fixation in children?
- Observing how well a child can fixate is crucial qualitative assessment
- Fixation to a light: assess corneal reflections
o Held at 33cm
o Can be moved around to see if child fixes & follows
o Introduce small bright colourful toys – do they fix & follow - Useful tool in pxs who are uncooperative for FCPL/ are suspect very reduced vision
Describe fixed preference in strabismus? What does it mean for vision?
- Cover test results can give clues regarding vision
- Child will ALWAYS choose to fix with eye that is best seeing
- Alternating squint:
o Equal or near equal vision between the 2 eyes - Holds fixation briefly:
o Small difference in vision between eyes – usually <2 lines
o They can use the eye and happy to but not for very long – must not be very poor in that eye - Does not hold fixation:
o Likely significant difference in vision (> or equal to 3 lines)
o Minute you tke away cover – no ability to use that eye – indicates that child has significant difference between eyes vision not as good in this eye - Slow to take up fixation:
o Likely very reduced vision
o Vision is reduced, using non-absolute eccentric fixation – not using fovea to look - Slow to move & only moves out slightly:
o Non absolute eccentric fixation - Doesn’t take up fixation at all:
o Eccentric fixation
o Eye does not want to use fovea as vision so poor
Describe testing a baby (0-18months)?
- These tests can be used in older children or equally 18month old may need an older child test
- FCPL:
o Principle – infants prefer to look at patterned rather than a blank surface
o Keeler or Teller Acuity Cards:
17 cards w/ black & white stripes on right or left side
1 blank card – to see if child has favourite side or decide between the two
4mm hole in centre where examiner looks through
o Square-wave gratings of different spatial frequency
Spatial frequency = cycles/degree
o The narrower the strip:
Higher number
Higher spatial frequency – closer stripes together (harder to see)
Higher VA
o Range of 0.18-38 c/deg gives you a logMAR equivalent on back of each card
o Suitability:
8 weeks to 6-12 months (can try before 8 weeks if think it’ll work)
Pxs with mental & physical disabilities – Cardiff Cards usually preferred method due to larger range
o Method:
38cm testing distance
2 correct responses means you can move to next (they look at same side twice)
“Staircase method” – presenting grating same number of times, moving up to next higher frequency & down if incorrect
Stop when examiner can no longer make judgement on response - Cardiff Acuity Cards:
o Grey cards with familiar pictures
o Vanishing optotypes
o Picture beyond acuity threshold = invisible to px
o Picture at top or bottom of card
o 3 cards for each acuity level
o VA Range:
6/60-6/6 at 1m
6/120-6/12 at ½m
o Suitability:
6/12 – 2year old
Children & adults with disabilities
o Method:
Cards are held at 50cm or 1m
Present cards at eye level – don’t look at card first – get child to look at picture first, see where they look then you look at the card to confirm if they got it right
Begin with card with most obvious target (lowest acuity)
Can be done at 50cm or 1m – younger the child the closer you’ll be to keep their attention
Observe eye movements
2 out of 3 correct response
Can overestimate vision – know child is seeing something but don’t know what they can see – they may be able to differentiate contrast but don’t know if they can actually see a duck for e.g.
Can be used in non-verbal children
Describe testing a toddler/infant (18months-3years)?
- Kay Pictures Test:
o Series of well-known pictures in a flip book
o If child shy they may still want to match with you
o Pages with smaller acuities have 2 lines per page
o Available in two formats
o Comes with matching card
o Suitability:
2-3 years
Estimate: - Single Kays 2-3years
- Crowded Kays >3 years
o Kay Picture Single logMAR:
Based on same principle as logMAR acuity test
3m testing distance
1 picture per page
For each acuity level there are a few different pictures – don’t need to do every picture for every level
Method: - Occlude 1 eye
- 3m testing distance
- Choice of 3-4 pictures per acuity level
- VA range 1.00-0.00 logMAR
o Kay Picture Crowded logMAR:
Older – better ability to see and concentrate & speak
More accurate than single
5 pictures in a line of reducing size
Linear, crowded test
Same principle as logMAR acuity tests
Method: - Occlude 1 eye – use occlusive glasses not parent’s hand
- Matching card
- 3m testing distance
- 5 pictures in a line with crowding box
- Count number of pictures seen on smallest line correctly identified – each picture on new book counts as 0.020
- VA range 1.00 to -0.100 logMAR
Describe testing pre-school (4-5years)?
- logMAR Crowded Acuity Test:
o Glasgow Acuity test (Keeler) – 3m
o 3 books & matching card
2x crowded books - 4 letters per acuity level inside crowding box
- 1 book for each eye so child doesn’t memorise letters
1x uncrowded book - 2 letters per acuity level
o One line of letters is 0.1logMAR
o Each letter worth 0.025 logMAR
o Suitability:
Preschool (3-5year olds) – most accurate and reliable for this age group
o Method:
Test at 3m
Practice with matching card first
Recording same as logMAR – smallest row of letters/no. of letters seen recorded
What is an important rule about logMAR compared to Kay Picture?
0.100 in crowded logMAR = 0.200 in Kay Picture test
Describe Sonsken test?
- Designed by University College of London
- Based on ETDRS
- Similar to crowded logMAR
- 2 flip books
- 4 letter with crowding bar
- Matching card
- 3m testing distance
- Overestimates vision – be careful when recording results
- Cheaper
- Near vision card
What things should you consider if you suspect reduced vision?
- How parents think the baby sees
o Parent usually knows if their baby is visually impaired – may respond to noise but not respond when someone walks into room - Does the baby make eye contact?
o Look at baby up close – will they look at you - Does the baby respond or copy facial expressions?
o Silent smile at px (don’t say anything or make noise) – and they smile back then likely they can see your smile - Does the baby notice if the lights are switched on/off? – are they surprised, do they look around
- Do baby’s pupils react?
o Should be light sensitive to bright light & squirm away – if they don’t do that then likely they cannot see it
Describe the crowding effect?
- Better acuity is usually achieved in targets which are spread apart compared to targets that are closely spaced
- Normal & amblyopes
o Amblyopes vision poorer when crowding rather than without crowding - Characteristic of microtropia
- Crowding occurs when letters are 1 letter diameter apart with resolution maximally impaired when 0.4 letter diameter apart
Describe testing near vision in a child?
- Testing distance 33cm
- Same rules apply about grading & logMAR – just doing it up close
- Typeset material:
o Similar to newspaper print/book print – sentences, paragraphs, words
o Not comparable to distance VA tests
o N test types (Times New Roman)
o Moorfields book
o Maclure book - Based on equivalent to distance chart:
o Reduced Snellen
o logMAR chart
o Near single & crowded Kay picture (logMAR)
o Single Sheridan Gardener
Which test would you pick for each age group?
Birt-6mths? 1-2yrs? 2-3yrs? 3-4yrs? 4-8yrs? 8+yrs
Birth-6mths –> preferential looking
1-2yrs –> Cardiff Cards
2-3yrs –> Kay Pictures Single
3-4yrs –> Kay Pictures Crowded
4-8yrs –> Crowded logMAR
8+yrs –> logMAR chart