Assessment Of Binocular Vision In Children

Question 1

How can we tell if a patient has BV or not

Answer 1

• aligned visual axis
• corneal reflections
• cover test

Question 2

Normal Level of vision in children (18-23mths),(24-29mths),(30-36mths)

Answer 2

18-23 - 6/24 to 6/7.5
24-29 - 6/15 to 6/7.5
30-36 - 6/12- 6/6

Question 3

Challenges of testing infants

Answer 3

• Can’t speak - struggle to verbalise subjective prescription
• Can’t read - letter testing impossible
• lose concentration
• lose interest

Question 4

How to be successful in testing children

Answer 4

• choose age appropriate test
• be engaging
• beware of behavioural cues
• use comfortable occlusion

Question 5

What is a Qualitative assessment

Answer 5

• estimation of VA
• based on Px reactions
• comparing behaviour for both eyes
• assess fixation
• reaching for objects

Question 6

What is a Quantitative assessment

Answer 6

• precise measure of VA
• requires Px to identify the minimal separable
• logMAR
• Cardiff acuity cards
• preferential looking

Question 7

What is optokinetic nystagmus, and how is it tested

Answer 7

• a physiologic phenomenon produced by asking the patient to visually track a succession of moving stimuli
• OKN drum
• stripes move across field of vision
• Px focuses on one stripe, then a quick movement in the opposite direction
• drum is rotated vertically in front of infant and response is observed

Question 8

How to assess fixation

Answer 8

• fixation to a light To assess corneal fixation
• held at 33cm
• torch can be moved around to see if it can be followed
• bright colourful toys
• using ophthalmoscope, with graticule looking for white reflex

Question 9

Fixation preference in strabismus

Answer 9

• alternating squint -> equal or near equal vision
• Holds fixation briefly -> small difference in vision (2 lines)
• does not hold fixation -> slight difference in prescription (3 lines)
• slow to talk up fixation: likely very reduced
• slow to move, and only moves slightly -> non absolute eccentric vision
• doesn’t take up fixation at all

Question 10

How to testVA in a baby

Answer 10

Forced choice preferential looking

Question 11

FCPL principle

Answer 11

• infants prefer to look at patterned background, rather than a blank surface
• Keeler or teller cads
• 17 cards with black white stripes
• 1 blank card
• hole in the centre
• square wave gratings of different spatial frequencies
• spatial frequency = cycles/degree
• range of 0.18 - 38 c/degree

Question 12

Who is suitable for FCPL

Answer 12

• 8 weeks to 6/12 months
• mental disability

Question 13

FCPL method

Answer 13

• 38cm distance
• 2 correct responses means move to next level
• staircase method - up if correct, down if wrong
• stop when can make any more judgement

Question 14

What are Cardiff Acuity cards

Answer 14

• grey cards with familiar pictures
• vanishing optotypes
• picture beyond acuity threshold = invisible to Px
• picture at top or bottom
• 3 cards for each acuity level

Question 15

Who is suitable for Cardiff acuity cards

Answer 15

• 6/12 months to 2 years
• children & adults with mental disability

Question 16

Cardiff cards method

Answer 16

• held at 50cm or 1m
• present cards at eye level
• begin with most obvious target
• observe eye movement
• 2 out of 3 correct response to move up

Question 17

How to test VA in a toddler

Answer 17

Kays picture test
- single logMAR
- crowded logMAR

Question 18

What is Kay’s pictures

Answer 18

• well known pictures in a flip book
• pages with smaller acuities have 2 lines per page
• available in 2 formats
• comes with matching card

Question 19

What is single logMAR Kays pictures

Answer 19

• based on same principle as logMAR acuity testing
• 3m testing distance
• 1 picture per page

Question 20

What is crowded logMAR Kay’s pictures

Answer 20

• 5 pictures in a line of reducing size
• linear crowded test
• same principle as acuity tests

Question 21

Suitability for Kay’s picture

Answer 21

• 2/3 years

Question 22

Kays pictures method - single

Answer 22

• • occlude 1 eye
• 3m testing distance
• choice of 3/4 pictures per acuity level
• VA range from 1.00-0.00 logMAR

Question 23

Method - crowded Kay’s pictures

Answer 23

• 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 0.02
• VA range from 1.00-0.100 logMAR

Question 24

How to test Pre-school children

Answer 24

LogMAR crowded acuity test
- 2x crowded books
- 4 letters at each acuity level inside box
- 1x uncrowned book
- 2 letters at each acuity level

Question 25

Suitability of crowded logMAR

Answer 25

Preschool

Question 26

Crowded logMAR method

Answer 26

• 3m
• practice with matching cards first
• record the same os logMAR
• 0.100 in crowded logMAR = 0.200 in ky pictures

Question 27

What is sonsken

Answer 27

• based on ETDRS
• similar to crowded logMAR
• 2 flip books
• 4 letters within crowding bar
• matching card
• 3m testing distance
• near vision card

Question 28

How to tell if there’s reduced vision in a baby

Answer 28

• how do the parents think the baby sees
• does the baby make eye contact
• does the baby respond or copy facial expressions
• does the baby notice if the lights are switch on/off
• do the babies pupils react