Week 1 - Assessment if infants and young children Flashcards
Normal values for vision in children?
• 18-23: 0.6-0.1 Logmar
• 24-29: 0.4-0.1 Logmar
• 30-36: 0.3-0.1 Logmar
(months)
Challenges when testing vision in infants:
• Communication
- Can’t talk- Can’t verbalise their subjective perception
- Can’t read- Standard letter testing not possible
• Concentration
- Easily distracted
- lack interest
How to be successful at testing infants/young children:
• Choose age-appropriate test
•Engage with the child- make it fun!
• Be aware of behavioural cues
Tips
1. Examiner consistency- gain trust.
2. Teach the child how to do the test first
3. Use comfortable occlusion- avoid parent’s hand.
4. If in doubt, test both eyes open.
What is a Qualitative test?
Useful in very young or uncooperative patients.
• Estimation of VA- Objective
•Based on patient’s reactions
•Compare the behaviour of the two eyes
Qualitative tests can overestimate vision…
Records the minimal visible versus the minimal separable in quantitative testing.
What is a Quantative test?
• Precise measurement of VA
• Requires patient to identify the minimal separable
How is a Qualitative test done?
• Assessment of fixation
• Reaching out for objects
• Hundreds and thousands
• Optokinetic nystagmus… OKN drum
Examples of Quantative test?
• Forced Choice Preferential Looking (FCPL)
•Cardiff Acuity Cards
• Kays Picture Test
• LogMAR
•Sonsken
How is Optokinetic nystagmus tested?
• OKN drum
- Easy to perform
• Qualitative information- similar to fix and follow methods
• Stripes that move across field of vision, create an eye movement
• Patient fixates on one stripe and then a quick movement in opposite direction
• Drum is rotated vertically in front of infant and response is observed
What are some less commonly used methods for quantitive testing?
• Lea Symbols
• Sheridan-Gardiner Test
• Landolt C
• Tumbling E
How is the assessment of fixation done on children?
Observing how well a child can fixate is a crucial qualitative assessment.
• Fixation to a light: assess corneal reflections.
- Held at 33cm
- Can be moved around to see if child fixes and follows
- Introduce small bright colourful toys- do they fix and follow?
What do different fixation preferences mean in strabismus?
• Alternating squint: Equal or near equal vision
• Holds fixation briefly: Small difference in vision between the eyes (Usually <2 lines)
• Does not hold fixation: Likely significant difference in vision (23 lines)
• Slow to take up fixation: Likely very reduced vision
• Slow to move and only moves out slightly: Non absolute eccentric fixation
• Doesn’t take up fixation at all: Eccentric fixation
Whats the guide tests recommended for a baby? (0-18months)
• Forced Choice Preferential Looking
(FCPL)
• Principle:
- Infants prefer to look at patterned rather than a blank surface
• Keeler or Teller acuity cards:
- 17 cards with black & white stripes on right or left side
- 1 blank card
- 4mm hole in centre
Explain how FCPL test acuity?
• Square-wave gratings of different spatial frequency
• Spatial Frequency = cycles/degree
• The narrower the strip:
- Higher number
- Higher spatial frequency
- Higher VA
• Range of 0.18 -38 c/deg
FCPL Suitability and method:
Suitability:
• 8 weeks to 6-12 months
• Patients with mental and physical disabilities (CC usually preferred method)
Method:
• 38cm testing distance
• 2 correct responses means you can move to next
• “Staircase method”- Presenting grating same number of times, moving up to next higher frequency and down if incorrect
• Stop when examiner can no longer make judgement on response
What are cardiff acuity cards?
• Grey cards with familiar pictures
• Vanishing optotypes
• Picture beyond acuity threshold= invisible to patient
• Picture at top or bottom of card
• 3 cards for each acuity level
Va range:
•6/60 - 6/6 at 1 m
•6/120 - 6/12 at ½ m
Cardiff cards Suitability and method:
Suitability:
• 6/12 - 2-year-old
• Children and adults with disabilities
Method:
• Cards are held at 50cm or 1m
•Present cards at eye level - don’t look at card first
• Begin with card with most obvious target (lowest acuity)
• Observe eye movements
• 2 out of 3 correct response
Recommend method for testing Toddler/infant:
Kay Pictures Test
• Series of well-known pictures in a flip book.
• Pages with smaller acuities have 2 lines per page
• Available in two formats
• Comes with matching card
What are the two types of Kay pictures tests?
• Kay Picture Single logMAR
- Based on same principle as logMAR acuity test
- 3m testing distance
- 1 picture per page
• Kay Picture crowded logMAR
- 5 pictures in a line of reducing size
- Linear, crowded test
- Same principle as logMAR acuity tests
Kays picture test suitability and method:
Suitability
•2-3 years
• Estimate:
- Single Kays 2-3 years
- Crowded Kays >3 years
Method:
Kay Picture Single logMAR
• Occlude 1 eye
•3m testing distance
• Choice of 3-4 pictures per acuity level
• VA range 1.00 - 0.00 logMAR
How is Kay picture crowded logMAR test done?
•Occlude 1 eye
•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 - -0.100 logMAR
Recommended method for testing pre-school age? (4-5years)
• Glasgow acuity test (Keeler) - 3m
• 3 books and matching card
- 2 x crowded books
- 4 letters per acuity level inside crowding box
- 1 x uncrowded book
- 2 letters at each acuity level
• One line of letters is 0.1 logMAR
• Each letter worth 0.025 logMAR
Glasgow acuity test (Keeler) - 3m suitability and method:
• Suitability:
Preschool (3-5 vear olds)
• Method:
- Test at 3m
- Practise with matching card first
- Recording same as logMAR - smallest row of letters / no. of letters seen recorded
Whats an important rule to remember between Cowded logMAR and Kay picture tests?
0.100 in crowded logMAR= 0.200 in kay picture test
Questions to ask if reduced vision in baby:
• How parents think the baby sees
• Does the baby respond or copy facial expressions?
• Does the baby make eye contact?
• Does the baby notice if the lights are switch on/off?
• Do the baby’s pupils react?
