Week 1 - Assessment if infants and young children

Question 1

Normal values for vision in children?

Answer 1

• 18-23: 0.6-0.1 Logmar
• 24-29: 0.4-0.1 Logmar
• 30-36: 0.3-0.1 Logmar
(months)

Question 2

Challenges when testing vision in infants:

Answer 2

• Communication
- Can’t talk- Can’t verbalise their subjective perception
- Can’t read- Standard letter testing not possible

• Concentration
- Easily distracted
- lack interest

Question 3

How to be successful at testing infants/young children:

Answer 3

• 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.

Question 4

What is a Qualitative test?

Answer 4

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.

Question 5

What is a Quantative test?

Answer 5

• Precise measurement of VA
• Requires patient to identify the minimal separable

Question 6

How is a Qualitative test done?

Answer 6

• Assessment of fixation
• Reaching out for objects
• Hundreds and thousands
• Optokinetic nystagmus… OKN drum

Question 7

Examples of Quantative test?

Answer 7

• Forced Choice Preferential Looking (FCPL)
•Cardiff Acuity Cards
• Kays Picture Test
• LogMAR
•Sonsken

Question 8

How is Optokinetic nystagmus tested?

Answer 8

• 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

Question 9

What are some less commonly used methods for quantitive testing?

Answer 9

• Lea Symbols
• Sheridan-Gardiner Test
• Landolt C
• Tumbling E

Question 10

How is the assessment of fixation done on children?

Answer 10

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?

Question 11

What do different fixation preferences mean in strabismus?

Answer 11

• 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

Question 12

Whats the guide tests recommended for a baby? (0-18months)

Answer 12

• 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

Question 13

Explain how FCPL test acuity?

Answer 13

• 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

Question 14

FCPL Suitability and method:

Answer 14

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

Question 15

What are cardiff acuity cards?

Answer 15

• 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

Question 16

Cardiff cards Suitability and method:

Answer 16

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

Question 17

Recommend method for testing Toddler/infant:

Answer 17

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

Question 18

What are the two types of Kay pictures tests?

Answer 18

• 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

Question 19

Kays picture test suitability and method:

Answer 19

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

Question 20

How is Kay picture crowded logMAR test done?

Answer 20

•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

Question 21

Recommended method for testing pre-school age? (4-5years)

Answer 21

• 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

Question 22

Glasgow acuity test (Keeler) - 3m suitability and method:

Answer 22

• 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

Question 23

Whats an important rule to remember between Cowded logMAR and Kay picture tests?

Answer 23

0.100 in crowded logMAR= 0.200 in kay picture test

Question 24

Questions to ask if reduced vision in baby:

Answer 24

• 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?

Question 25

What vision tests are recommended for each age bracket?

Answer 25

Birth-6 Months: Preferential looking
1-2 years: Cardiff cards
2-3 years: Kay pictures single
3-4 years: Kay pictures crowded
4-8 years: crowded LogMAR
8+ years: LogMAR Chart

Question 26

How are vision tests recorded?

Answer 26

• Which test was used- whether it was single or crowded!
• The threshold level
• The testing distance
• Changes in behaviour between the eyes eg. Slower with RE
• If a compensatory head posture was