7.1.4 Understands the techniques of the assessment of infants.

Question 1

<1 years old:

Answer 1

• Keeler/Teller Acuity Cards
  
  • Striped grating (black & white) on one side; identical blank outline on the other.
  • Keeler Version: Includes a white-bordered outline for both sides.
  • Visual Principle:
    
    • Stripes’ luminance matches the grey background.
    • Poor resolution acuity → Infant unable to resolve stripes → No visual curiosity towards either target.
    • Gratings measured in spatial frequency (number of black/white pairs per degree of visual angle). Higher frequency = finer grating.
• Testing Procedure
  
  • Examiner observes through a peephole to detect eye movements.
  • Working distance: 55 cm (matches card width for easy estimation).
  • Each grating presented 4 times, with the examiner requiring 3/4 correct judgments based on the infant’s eye movements.
  • Start with low spatial frequencies (SFs) → Build up to high SFs until the infant fails the 75% accuracy threshold.
• Vision Development Reminder
  
  • At 3 months of age, a child objects if the better-seeing eye is covered while viewing something of interest.
  • Gross vision loss unlikely if the child appears equally content and capable with either eye covered.

Question 2

1-3 years old (Assessor will ask you how these cards work!)

Answer 2

• Cardiff Acuity Cards
  
  • Features pictures (vanishing optotypes) for better engagement, particularly for patients over 1 year old.
  • Vanishing Optotypes:
    
    • Pseudo high-pass design; target luminance matches background.
    • Targets become indistinguishable from the background beyond resolution acuity.
• Use Case
  
  • Suitable for patients who cannot recognize/match letters or numbers.
  • Measures VA range: 6/60 to 6/3.8.
  • Testing distance: 50 cm to 1 m (adjusting WD affects reliability).
• Testing Procedure
  
  • No peephole; examiner observes child’s eye movements as cards are presented vertically.
  • Begin at eye level; estimate gaze direction (up or down) based on eye movements.
  • If both initial guesses are correct, move to the next set of cards.
  • At threshold:
    
    • Present the same acuity target 3 times with different pictures to confirm reliability.
    • Always conclude with an easier target to ensure a positive experience.
  • If wrong or uncertain fixation: Repeat the previous set using all 3 cards.
• Considerations
  
  • Not sensitive to amblyopia. Crowded letters/pictures are more sensitive.
  • Strong rejection of occlusion = potential issue (e.g., amblyopia).
  • If only binocular testing is possible, reattempt monocularly after 6 months.

Question 3

Difference between Teller & Cardiff cards:

Answer 3

• Teller is preferential looking which just focus on resolution acuity
• Cardiff uses vanishing optotypes which focus on resolution & recognition due to the pictures, giving more precise endpoint
• Cardiff is in snellen notation but Teller is cycles per degree
• Teller has peephole, Cardiff doesn’t

Question 5

Visual Acuity (rough estimates)

Answer 5

New born VA: 6/120 – 6/360
1 year VA: 6/15 – 6/90
2 years VA: 6/9 – 6/24
3 years VA: 6/5 – 6/12

Question 6

Optokinetic nystagmus

Answer 6

From birth this develops symmetrically within 6 months but if strabismus present, lack of BSV disrupts this process & makes it asymmetrical. With rotating drum, if stripes going temporal to nasal & eyes all AOK, then normal response. If at the same time, stripes then went nasal to temporal & eyes have no response or abnormal eye movements, then abnormal OKN.

Question 7

H+S questions for 2year old or under…

Answer 7

• LEE - if eye test previously, what did they say/give any spex?
• Do you have any concerns about the eyes?
• Noticing any problems with the eyes? Like eye turns, sensitive to bright lights, bumping into things? Head tilts?
• Do they seem to be able to see things OK when you point to objects?
• Any health conditions/any illnesses they’ve suffered from? Anything hereditary?
• Any problems during delivery? Forceps, c section, premature, low birth weight, put on oxygen after birth. What was their birth weight?
• FH of squints, lazy eye, spex wearing (record hyperopia or myopia & if no myopia in family then record “no myopia”), patching?
  
  • Any patching done?
• FH of diabetes, colour vision defects?
• Any trips to the HES for eyes? Infections? Injuries to eyes or accidental or non-accidental head trauma?

Question 8

Assessment of child VA, aged 18 months:

Answer 8

• Preferential looking using Cardiff Acuity Cards - for patients unable to name or match letters or pictures
  
  • Assessor will observe the child’s eye movements as confirmation that they see the target
  • Cards are optotypes that rely on resolution acuity (detect & resolve a target), so when child cannot resolve any further, the card will look grey and they won’t show interest
    
    • Not sensitive to amblyopia! Crowded letters & pictures are, however, sensitive
  • Cards presented at 50cm or 1m
  • When reaching threshold, show same acuity target 3 times (preferably with different pictures) and if child could see them then that’s reliable enough
• If a child significantly rejects occlusion after repeated attempts, then you should be highly suspicious
• End with a much easier target than threshold so that you always end on success
• Don’t forget that as the child kept moving forwards to see more easily, this affects the working distance & overall reliability
• If you could only do binocular on the day, review after 6 months & reattempt monocularly

Question 9

Stereopsis, aged 18 months:

Answer 9

• Lang
  • Requires no glasses but working distance of 40cm
  • It’s a random dot stereo test where dissociation is given by vertical cylinders (splits the image to both eyes) arranged on the front surface of the card. Without stereopsis, it looks like grey dots. With stereopsis, there is a car, cat & star in the first edition of the test.
  • With a young child, the card is held so that hopefully they fixate on the “floating” image. When the card is reversed or turned vertically, they should fixate on the same image. This verifies that they have stereopsis. They will also be encouraged to point to the image, if they are able to
• Frisby
  
  • No glasses needed
  • Contains real stereo disparity - “ball” is on one side of the Perspex plate, the rest/background of the pattern is on the other side
  • A range of stereo disparities can be presented using this test at different distances
• Stereopsis should be grossly there by 3-4 months but at an adult level by 6-9 months
• The whole point is to determine if stereopsis is present or not, not measuring it

Question 10

Refraction, aged 18 months:

Answer 10

• Cycloplegia using 1% cyclopentolate hydrochloride for children 1+ years old otherwise 0.5%
  
  • 1 drop each eye, then check after 10 minutes as a further drop may be required for dark irises. Dilation of pupil comes before cycloplegia. Keep fingers over puncta to prevent dripping onto nose
  • Should be there 30-40 minutes after but if retinoscopy fluctuates still then full cycloplegia not achieved
• Need to hold both lenses up at same time if no trial frame is used. Why? Otherwise occlude eye not being retted, normally with parent’s help