This document provides information on visual acuity assessment in pediatric patients. It discusses visual development from gestation through childhood. It outlines requirements for normal visual development and visual milestones. Methods of assessing visual acuity are described for preverbal, preliterate, and verbal pediatric patients using techniques such as fixation preference, optokinetic testing, preferential looking tests, and visual acuity charts. Factors to consider when performing assessments and recording vision are also reviewed.

1. Visual Acuity
assessment in
Paediatric
patients
Dr.Anisha Rathod
MS,FPOS(Pediatric
Ophthalmology And Strabismus)

2. FINANCIAL DISCLOSURE
THE AUTHOR HAS NO FINANCIAL INTEREST IN THE SUBJECT MATTER
BEING PRESENTED

3. Visual Development
8-15 weeks gestation -Most ganglion cells are generated.(2.2-2.5million.)
30 weeks -Rapid cell death up to 6-8 weeks. It continues at low rate –( 1-
1.5 million.)
At birth Fovea covered with multiple cell layers+ sparsely cones (20/400)
-New born White matter(visual pathway)- not fully myelinated.
Enlarges(2 yrs),later slowly for first decade.
1st years of life- Photoreceptors redistribute+ foveal cone density increases five
fold (20/20)
2 nd year Neurons of LGB are 60% and increase up to 2 years.
1o years of age. Synaptic density attains final adult

4. REQUIREMENTS FOR NORMAL
VISUAL DEVELOPMENT:
– Clear retinal image
– Equal image clarity
– Proper eye alignment.

5. Visual milestones
Few days of birth -Blink reflex to bright light.
31 weeks of gestation Pupillary response.
6-8 weeks Eye contact+react with facial expressions.
2-3 months Interest in bright objects
3-4 months Smooth pursuit asymmetry,orthotropic,fixes and follows
4 months Accomodation appropriate to target.
-6months-2 years- Central fixation,reaches for toys,stereopsis.
3-5 years-.
->More than 5 years
20/40 and not more than 2 Snellen lines difference
-20/30 and not more than 2 Snellen lines difference.

6. Poor visual development signs:
– Poor fixation at 6 months
– Searching eye movements
– Lack of response to familiar objects and faces and nystagmus.
– Staring at bright light and forceful rubbing/poking of eyes(oculodigital reflex)

7.  Visual acuity is the measure of the spatial resolution of the eye/ estimation of ability to differentiate between
two points.
In Paediatric age group,different approaches are required depending on the age and co-operation of the child.
Divided as
-Preverbal
-Preliterate/not fully cooperative,
- Verbal.

8. Points to remember while recording vision
– 1. Record vision in normally lighted room. Most suitable infant to examine for vision is an awake, alert baby.
– 2. Allow one of the parents .
– 3. Note the vision with both eyes open.
– 4. It is better to examine eye with better vision first and the other eye later.
– 5. Children above five years of age can memorise the Snellen’s chart .Better to ask the child to read from right to left
– 6. While examining one eye the other eye should be occluded completely and watch that child does not peek over the
occluder.
– 7. Keep the head of the child in primary position.

9. Preverbal Subjects
– Motor or sensory response to a threshold stimulus of
a known size known as testing distance.
– In infants and toddlers , fixation behaviour is
observed .
– Method:
– Child’s attention directed to examiner’s face/small
toy in hand.
– Fixation preference –response on covering 1 eye
compared with the other eye.
– Strong fixation preference in 1 eye indicates
decreased vision in the non preferred eye.

10. – Fixation is characterised by the CSM(Central,Steady and Maintained)method.
– Types are monocular and binocular.
– Central:
– It refers to foveal fixation with centrally located corneal reflex,tested mono ocularly.
– Fixation target viewed eccentrically-Uncentral(UC)
– Steady(S):
– It refers to absence of nystagmus and other motor disruptions of fixation.
– Maintained:
– It refers to fixation of that is held after opposite eye is uncovered.
– An eye that does not maintain fixation under binocular conditions-lower visual acuity than opposite eye.

11. Cover test
 Manifest squint - The cover test-
constant/intermittent,unilateral or alternating.
 Intermittent or alternates without preference for
fixation with one eye-the vision same in each eye.
 Squint is unilateral/preference for fixation with one
eye- vision less in the squinting eye

12. Induced tropia test
Indication:
Small-angle strabismus/no strabismus.
Method:
- Examiner directs attention of subject towards target.
- A 10-15 prism dioptre base down prism is placed in 1 eye.
- If the eyes move up-the child using the eye under the prism
– Interpretation:
– Subject choses the eye with the prism/the eye without the prism -
no preference is present.
-Continuously fixates with the same eye-opposite eye has
decreased vision.
– Eccentric fixation +nystagmoid movements when attempting
fixation-Uncentral,Unsteady,Unmaintained.

13. Preferential looking test/Keeler Acuity Chart
– Observing the child’s response to a visual stimulus.
– Teller acuity cards –A series of rectangular cards
with alternating black and white stripes printed on
a gray background.
– Stripes are printed on one side of the card only.
– Movement of eyes towards the side with the
stripes indicates that the child is able to see them.
– Stripe width decreases on successive cards.
– Seeing narrower stripes denotes better vision.
– Drawback:
– Tests near vision not distance vision.

14. Optokinetic Drum test of Harcourt
– Used in neonates.
– Object with printed images moves in one direction
– Pendular movement(Nystagmus elicited) of eyes is observed.
– Drawback:
– Overestimates the visual acuity as the target is moving.
– OKNOVIS:
– Principle of arresting an elicited optokinetic nystagmus by
introducing optotypes of various sizes.
– The instrument is a hand held revolving drum that rotates at
speed of 12 revolutions per minutes.
– Done at 60cm .
– Once nystagmus is elicited optotypes of different sizes are
introduced to arrest nystagmus.

15. Catford Drum test
– Based on pendular eye movements.
– Comprises of white cylinder marked with black dots of
increasing size corresponding to visual acuity.
– The drum is masked by a screen except for rectangular
aperture which exposes a single spot.
– Spots are made to oscillate horizontally and stimulate eye
movement.
– Drawbacks:
– Overestimates vision as target is moving and test is
conducted at short working distance.
– Unreliable for screening amblyopia.

16. Bruckner test/Red reflex examination
– Semi dark room -the red reflex from both eyes simultaneously at a distance of 1 metre.
– Most infants and children look towards direct ophthalmoscope.
– The clarity and symmetry of the red reflex and identify significant/asymmetric refractive errors and
ocular misalignment.

17. Visual field testing
– Can be done in children of 4 months of age.
Method:
– Presentation of a peripheral target while child
fixates on an interesting central target.

18. Visual field testing
– Movement of the eyes on peripheral target confirms the field.
– Visual fields can be approximated by confrontation in children old enough to count or match fingers
placed in each quadrant.
– School aged children can be evaluated by automated perimetry.

19. Visually evoked potential
– Electrodes are placed over occipital lobe.The child views a
stimulus with series of bar or grid patterns.
– The strip width narrows to the point that the stimulus appears
uniform gray at which point no impulse is recorded.
– Visual acuity is estimated on the smallest line width that
produces a response.
– Interpretation:
– Abnormal VEP may indicate a problem with visual information
reaching the cortex.
– Used in amblyopia , cortical blindness and other visual
impairment.

20. Preliterate Children
– The smallest target of a known size at a known
testing distance correctly verbally identified by
the child.

21. Cardiff Acuity Test
– The vanishing optotype acuity test (Cardiff test).
– Method:
– They consist of black and white stripes on a neutral grey
background; the average luminance being equal to the
background.
– The optotype fades completely into the background-retinal image
is not resolved, making it invisible rather than blurred.
– 33 cards with six shapes which are easily recognisable (house,
fish, dog, duck, train, car), positioned either at the top or bottom
half of a card .

22. Advantages:
It is quicker, more user - friendly and is generally liked by the
children.
The end point is often very clear cut, the child suddenly losing
interest when no shape is perceived.

23. Lea’s Symbol Test
– Used in children between 2-3
years.
– Good for amblyopic patient to
avoid crowding phenomenon.

24. Boeck Candy Test
– The child is asked to pick up beads of 1 mm in size at 40 cm.
– Snellen’s equivalent is estimated by this method.

25. Miniature Toy Test
– 2 sets of miniature object are used.
– The Child is shown a miniature toy from 10
feet and asked to name or pick a pair from the
assorted toys.

26. Worth’s ivory ball test
– Ivory balls 0.5 to2.5” in diameter are rolled on
the floor in front of the child and the child is
asked to retrieve each.
– Acuity is estimated on the basis of smallest size
for test distance.

27. Allen’s Picture Cards
– Recorded as Snellen’s acuity test
– Instead of letters ,the child identifies pictures at a
distance of 6 metre.

28. Snellen’s Visual Acuity Chart
– This test mainly comprise letters arranged in horizontal rows
of diminishing size (linear vision charts)
– Used in verbal children.
– The acuity of vision is determined by
– The smallest retinal image,
– The form of which can be appreciated,
– It is measured by the smallest object, can be clearly seen at
a certain distance.

29. LogMAR Visual Acuity
Charts
– Based on Minimum Angle Of Resolution
– Regular progression in size and spacing of
letters from one line to next.
– Same number of letters on every line.
– Snellen fraction is inverted and reduced.

30. Sheridian Gardener Letter Test
 (Matching Test) Uses letters which are circular, square or
triangular shapes, which children can recognise and copy at
an early age.
 VTOHXAU -shown to the child one at a time on flip- over
cards.
 The child is given a key card showing all the letters, which
he or a parent holds, and he points to the letter he sees.
 The Sheridan Gardiner test is the most accurate of the
illiterate vision tests.
 The choice of letters is large enough to avoid the child
guessing and it is easy to use

31. Lippman’s HOTV test
– Simpler version of Sheridian test using 4 letters HOTV
– Test distance is 3 metre.
– STYCAR(Screening test for young children and retards)
also uses HOTV for assessment of vision.

32. Tumbling E Test
– This test is also based on matching shapes, where a
wooden or plastic letter E is turned up, down, to right or
left to match the position of the E on the chart or card

33. Landolt’s Broken Ring
Chart
– The rings are constructed on the same basis as that of Snellens.
– Child is instructed to indicate by the motion of the hand at
which point each one is broken.
– Interpretation of the last line identified by the child determines
visual acuity.

34. Cambridge crowding cards
– Cambridge crowding cards These charts are used to detect the crowding phenomenon in amblyopic
patients of age group 3-6 years.
– Best test for assessing the prognosis of occlusion therapy in amblyopia.
– If standard linear acuity not achieved-there is a strong possibility that the visual acuity in the amblyopic
eye will regress significantly.

35. Testing in Low Vision
– If visual acuity is less than 6/60 it can be assessed and recorded as follows:
– 1. By moving the patient closer to the chart in one metre steps (or by moving the chart closer to the patient)
– 2. Vision less than 1/60, the patient is asked to count the number of fingers, which the examiner holds up at his
eye level at half a metre distance. (CF at ½m).
– 3. Vision is not enough to see the number of fingers-the patient is asked to say whether he sees the examiner's
hand moving when it is held in front of him(HM at ½m).
– 4. If hand movements cannot be detected-the patient is asked to say when he sees a light held at ½m distance
whether it is on or is switched off. Perception of light (PL).

36. ETDRS
– Early Treatment Diabetic Retinopathy Study (ETDRS) charts, based on
adaptive psychophysics methods and to assess the method’s validity
and reproducibility.
– As an alternative to snellen’s ETDRS chart can be used in cooperative
children and in children with low vision.
– The characteristics of ETDRS charts are having same number of letter
per line.
– There are a total of 14 lines with geometric progression of letter size
based on LogMAR scoring.
– It also has an advantage of usage at variable working distance (1m, 3m
and 4m).

37. Pupillary light reflex
– New born-Miotic pupil that increases in size until pre teen years.
– Briskly reacting pupil-Good ocular and optic nerve function.
– Sluggish response/no response at all-Retina/optic nerve dysfunction.
– Digital photography can be useful for accurate assessment and documentation.
– Important points before examining the pupil:
– Illumination of the room should be low,
– The patient should look at distance,
– The light used should be focussed and bright.

38. Colour vision
– Ishichiara pseudochromatic colour plates work on principle of color confusion.
– Advantage:In illiterate form with geometric shapes can be traces with fingers.
– Useful in children with comprehension and fine motor skills.
– Richmond pseudoisochromatic plates(American Hardy Randy Rittler plates)work on colour saturation and can
detectred green and blue yellow defects.
– Optic nerve diseases-Red green perceptions.
– Retinal disease:Blue Yellow discrimination
–

39. Contrast Sensitivity
– It is more sensitive test of visual function than Snellen Acuity as it assesses only high contrast resolution.
– The contrast sensitivity threshold is the minimal amount of contrast required to detect sinusoidal grating of
different spatial frequencies.
– The Pelli Robson chart is commonly used.
– The charts are placed at 1 metre from the patient and asked to read smallest letter possible.
– It is indicated in patients who have visual problems inspite normal visual acuity.

40. Near Vision
– Children under fifteen have strong accommodation .
– Hence their near vision is good .
– Complain of diminished vision children with high uncorrected hypermetropia may complain of asthenopia and
running of letters.
– If a child complains of diminished near vision the first test is to exclude hypermetropia by cycloplegic refraction.

41. Cycloplegic refraction
– Important due to correlation between accommodation and ocular convergence for assessment of
binocular vision and ocular motility.
– Cyclopentolate (1%)is the preferred drug for routine use in children.
– Homatropine 5% are used instead of cyclopentolate.
– Combination of cyclopentolate and tropicamide is used for maximum dilatation.
– Atropine 1% is used but is associated with systemic toxicity

42. Thank you