Assessment of Vision in Infants & Children Flashcards

1
Q

When are vision levels about normal from in children?

A
  • 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
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2
Q

What are the normal values for vision in children? 18-23 motnhs, 24-29 motnhs, 30-36 months?

A

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

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3
Q

Describe Qualitative Assessment in children?

A
  • 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
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4
Q

Describe Quantitative Assessment in children?

A
  • 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
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5
Q

Describe assessment of fixation in children?

A
  • 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
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6
Q

Describe fixed preference in strabismus? What does it mean for vision?

A
  • 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
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7
Q

Describe testing a baby (0-18months)?

A
  • 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
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8
Q

Describe testing a toddler/infant (18months-3years)?

A
  • 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
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9
Q

Describe testing pre-school (4-5years)?

A
  • 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
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10
Q

What is an important rule about logMAR compared to Kay Picture?

A

0.100 in crowded logMAR = 0.200 in Kay Picture test

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11
Q

Describe Sonsken test?

A
  • 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
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12
Q

What things should you consider if you suspect reduced vision?

A
  • 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
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13
Q

Describe the crowding effect?

A
  • 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
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14
Q

Describe testing near vision in a child?

A
  • 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
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15
Q

Which test would you pick for each age group?
Birt-6mths? 1-2yrs? 2-3yrs? 3-4yrs? 4-8yrs? 8+yrs

A

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

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16
Q

What do you need to record when noting child’s vision test results?

A
  • Which test was used – whether it was single or crowded (as next examiner may think vision should be better if you have not noted down correctly)
  • The threshold level – encourage child to get to threshold & max level of vision you can – child will want to give up quickly when it gets hard as they don’t want to be wrong
  • The testing distance
  • Changes in behaviour between the eyes e.g. slower with RE
  • If a compensatory head posture was used – if child has nystagmus they may use this to get null point (best vision)
  • Note if glasses were worn or not