7.1.3 Assesses children's visual function using appropriate techniques

Question 1

What are the normal levels of vision for different ages?

Answer 1

• Birth: 6/300
• 1 mth: 6/200- 6/90
• 3mths: 6/90-6/60
• 6mths: 6/90-6/60
• 9mths: 6/36-6/30
• 1yr: 6/18
• 18mths: 6/12
• 2yrs: 6/12-6/9
• 3-4yrs: 6/9-6/6
• 5-6yrs+: 6/6-6/5

Question 2

What are the average Rxs for different ages?

Answer 2

• 1-3mths: +3.00
• 6mths: +2.50
• 12 mths: +2.00
• 18 mths: +1.50
• 2 yrs: +1.25
• 3 yrs: +1.00
• 4-6 yrs: +0.50

Question 3

What is static retinoscopy?

Answer 3

o Achieved by distance fixation, use an interesting target, talk and keep child engaged
o Accommodation relaxed

Question 4

What is dynamic retinoscopy?

Answer 4

o Accommodation is kept active, Child fixate at accommodative target at child’s WD
o Measures effectiveness of accommodation
Procedure
1) The target for your patient should be an accommodative stimulus (letters)
2) The working distance for this technique is 40 cm
3) The patient’s distance prescription should already be in place
Þ You do NOT fog the other eye
4) The target should be placed at the same distance as your retinoscope
5) Lights should be dim enough for you to see the reflex, but for bright enough for the
patient to see the target

Question 5

What are the results of dynamic retinoscopy and what do they tell you?

Answer 5

Results of Dynamic Retinoscopy
* Neural Reflex: The patient has accommodated precisely to the near target
Þ Accommodative response = Accommodative Stimulus
* With Movement: the patient accommodates less than they should – an accommodative
lag
Þ Accommodative response < Accommodative stimulus
* Against Movement: The patient accommodates more than they should – an
accommodative lead
Þ Accommodative response > Accommodative stimulus
Typically, a patient will accommodate less than they need à an accommodative lag.
How to Interpret the Results of Dynamic Retinoscopy
1) You need to measure the amount of accommodative lag or lead
Do this by estimating the size of the reflex
Or
By placing the lens in the power of the estimated lag or lead infront of the eye & quickly checking
the response
Þ You can only hold the lens in place for half a second, as it will disrupt the accommodative
response & give a false reading
2) Examine the reflex across the horizontal meridian only & record the power required to
achieve neutral
3) Record the dioptric power required to achieve neutral
o e.g. RE +0.25 DS, LE +0.75 DS
* If lag is more than +1.00 DS, accommodative insufficiency is expected
* If lead is found, it suggests accommodative spasm

Difference in lag between eyes: Uncorrected anisometropia
Difference in lag between meridians: uncorrected astigmatism.

Question 6

What is mohindra technique?

Answer 6

Modification of near fixation ret
Occlude one eye, ret one eye at 50cm, assumes light is poor stimulus to accommodation
Room must be completely dark
Use loose lenses
Correction factor of -1.25DS added to ret result

Question 7

Describe the management of rx and when to prescribe?

Answer 7

Hyperopes >6D do not emmetropise
Under 2-3 years old: monitor Rx overtime
Over 2-3 years old: prescribe significant Rx
Prescribe:
o Myopia of -0.75D or greater
o Astigmatism of 2.50D or greater
o Hyperopia of +3.00 as its likely to be amblyogenic

Question 8

What is amblyopia?

Answer 8

a lack of visual stimuli to one or both eyes during the critical period resulting in
structural and functional damage in the LGN and V1 in the form of atrophy of connections, lack of
cross-linking between connections, a loss of laterality of connections. This leaves the child with
permanently reduced VA.

Question 9

Describe VA charts for Children: Kay Pictures, sheridan gardner, Lea Symbols, Cardiff cards, logMAR crowded acuity?

Answer 9

Kay Pictures:
o Tested at 3m.
o Tests VAs at 6/4.8 – 6/36.
o Rows of 5 pictures for the child to identify.
o Can say out loud what they see or point to the same shape on the near card.
o Flipperbook
Sheridan Gardner:
o Tested at 6m
o 7 different letters are shown
o VAs range from 6/4.8 – 6/60
o Flipperbook
Not the best as it is uncrowded.
Lea Symbols
o Tested at 3m.
o 3 symbols used: house, apple and square
o VAs range from 6/4.8 to 6/24
o Can say outloud what they see or point to the same shape on the near card
o Flipperbook
Cardiff Cards: - tested at 50cm or 1m
- 6months - 2 yrs
- present at eye level - don’t look at card beforehand - watch for where eyes look
2 out of 3 correct responses
LogMA Crowded acuity: - Glasgow Acuity cards
- 2x crowded books and 1x uncorrected
- 3-5yrs
- one line of letters is 0.1 logMAR, each letter 0.025
- test at 3m

0.100 in crowded logmar is 0.200 in crowded kays

Question 10

Why is crowding important?

Answer 10

Crowding is important in detecting amblyopia, as amblyopic px’s perform worse on crowded
than uncrowded acuity tests.

Question 11

What are the expected levels of stereo for age? in seconds of arc, for Frisby test?

Answer 11

• Birth-3mths:
• 6mths: 600”
• 9mths: 300”
• 1yr: 210-170”
• 18mths: 170-150”
• 2yrs: 100-85”
• 3yrs: 85-55”
• 4yrs: 40-30”
• 5yrs: 30-20”
• 6yrs: 10-5”

Question 12

Describe common stereo tests?

Answer 12

• Lang: gross, no glasses req, Lang 1 measures to 550”, Lang II measures to 200”
• Frisby: no glasses req, 600-15”, get monocular cures from movement
• TNO: random dot, req red green gls, up to 15”
• Titmus Fly: uses crossed polaroid visor, noticeable monocular cues, fly 3552 -700”, 800-40” for graded tests
• Randot: modified Titmus, polaroid design, uses random pattern background to remove monocular cues

Question 13

Describe ocular muscle balance tests?

Answer 13

• Cover test: gives info on type, size, control of deviation, likely binocular function present & probable involvement of EOM anomalies
• Hirschberg: corneal reflex test - shows strabismus. 1mm = 20^
• 20^ BO test: motor fusion test up to 5yrs old. 20^ BO held over one eye whilst child looks at suitable fix target. Eye under prism should adduct rapidly to restore normal fusion and quickly abduct on removal of prism. Speek of fusion movement gives infication of quality of binocularity.
  –> 6 mths: 10^BO, 12-18mths: 15^ BO, >18mths: 20^ BO
  –> no movement implies no fusion or lack of attention
  –> slow to ovverccome prism or to recover implies poor fusion
• Prism fusion range: uses prism bar, from age 5. Normal range at near: 35-45^ BO, 12-8^ BI
• Motility: useful with cover test. Gives info on range of ocular movements and if concom or incom. Use interesting, colourful targets. Can also move child instead of target: ‘swinging infant’