Vision Assessment and Vision Screening in Children, Refractive Error and Spectacle Correction, Amblyopia, Strabismus and Nystagmus

1. Vision Assessment and Vision Screening in
Children
Refractive error and spectacle correction
Amblyopia
Strabismus
Nystagmus
Rabindra Adhikary
M. Optom 1st Batch
Tilganga Institute of ophthalmology (TIO)
Pokhara University
Facilitators: Dr Srijana Adhikari, Dr Rojeeta Parajuli
Date: 4th of June, 2019

2. Pediatric Ophthalmology
– Layout
• Vision Assessment and Vision Screening in
Children
• Refractive error and spectacle correction
• Amblyopia
• Strabismus
• Nystagmus

3. Visual acuity
• Preverbal children
– Motor or sensory response to a threshold stimulus
– Known size at a known distance
• Pre-literate and verbal Children
– Smallest target of known size at known distance
correctly verbally identified by a child

4. Visual Milestones
Age Visual Behavior
0-1 month Fixate &Turns eye and head to look at the light source /
Looks high contrast object (mother’s hairline) + Horizontal Tracking
At 1 month, fixation is central, steady and maintained
3 month Vertical and circular tracking
Interested in mobiles
Lip-reading / responsive smile
6 months Reaches towards, and later grasps the hanging objects
Observes toys falling and rolling away
10 Looks for hidden toys
Interested in pictures
1 year Recognize people
2 years Picture Matching
3 years Letter matching of single letters
5 years Snellen chart by matching or naming

5. Gross Estimate of VA
Age Snellen’s Equivalent
Birth 6/120
4 months 6/60
6 months 6/36
1 year 6/18
2 years 6/6

6. Recognition Acuity
• Smallest number, letter or other shapes that
can be recognized
–

7. Resolution Acuity
• Preferential Looking
– Child prefers to look at the grating
• Striped grating
• Uniform filed
– Forced choice preferential looking (FCPL)
– 2 months to 1 year or pt with mental disabilities
– Visual threshold=75% correct inferences
• Drawbacks of PFL
– Difficult to hold a child’s attention for long
– Reliability is dependent on many trials
– Near test

9. OKN
• Drifting OKN generated by
– Resolvable stimuli
• Jerky Nystagmus
– Pursuit (follows target)
– Saccade (jumps to next)

10. VEP
• Measures electrical activity directly from the
scalp through surface electrodes
– Amplitude and timing of wave of electrical activity
– Go on presenting finer and finer stimuli
• Until zero response amplitude
• Abnormal VEP?
– Problem with the visual
information reaching cortex

12. Age-wise VA assessment
• Infants
– PFL/OKN/VEP
– Cat ford Drum
• 1-2 years
– STYCAR
• For retards too
– Boeck Candy test
– Worth’s Ivory Ball test
• 2-3 years
– Miniature Toy test
– Cardiff Acuity test
– Coin test
– Lea symbols
• 3-5 years
– Allen’s picture cards
– Sheridan’s HOTVX letter test
– Lippman’s HOTV Test
• 5-6 years
– Snellen

13. Screening
• Age ranges and visual/ocular pathology to be
detected by screening:
Pre-term Perinatal/infantile Pre-school School age
ROP Congenital cataract
Glaucoma
Anterior segment
disorder
Amblyogenic
factors
-anisometropia
-strabismus
-high refractive
error
-Ptosis
-Media opacity
Refractive error

14. Fixation Reflex
• CSM
– Monocular central fixation (C)
• No eccentric fixation
– Hold steady Fixation (S)
– Maintain fixation (M)
• With the viewing eye
• Even when the fellow eye is uncovered
• F + F
– Fixate and Follow the light stimuli
– Monocular viewing conditions

15. Pupillary Response
• Birth- 3 years (or upto when VA can’t be
measured)
• Pupil reactions to the changes of light stimulus
– Direct
– Consensual
• Not equivalent to visual ability but indicates
– Intact neurologic visual pathways

16. Red Light Reflex
• Bruckner Test
• 0-3 years
• Ophthalmoscope
– Position the light to illuminate BE
• Reflex
– Symmetrical
– Equal intensity
– Healthy red color

17. Corneal Light Reflex
• Hirschberg’s test
• 2 months- 8 years
• Strabismus (D/Dx: pseudostrabismus)
• Corneal reflection of Penlight
– Positioned symmetrically on both pupils

18. Cover test
• To know if eye deviates when fusion is
interrupted
– Observing the fixating eye when other eye is
covered (Cover test)
– Observing the eye being uncovered for movement
when the occluder is shifted to the other eye
(alternate cover)
– Observing the eye being uncovered for movement
when the occluder is removed (cover uncover)

19. Stereo-acuity
• 3-8 years
• Needs polarized glass
• Random dot E or stereo butterfly
• To check problems with stereo-acuity and
depth perception

20. Color vision
• At 6 years (first grader)
• Others: optional
• To check color deficiency
– Ishihara Pseudo-isochromatic Plates,
– Color Vision Testing Made Easy
– Good-Lite Book of Color Plates.
• Fluorescent desk lamp - if enough natural
daylight is not available.

21. Age vs Refractive Error
General Trends
Premature Infant High myopia ( ± ROP)
Newborn (full term) baby Hyperopia ( 1-2 D)
Toddler (preschool) Less hyperopia / low Myopia
(towards Emmetopia)
School Children Emmetropia or school myopia
Adolescent Myopia

22. Refraction
• Cycloplegic Refraction:
– Greater range of accommodation
– Fluctuating fixation
– Pseudomyopia
– Strabismus
– High hyperopia / latent Hyperopia
– Inconsistent results
• Near Retinoscopy

23. Prescription
• Should not interfere with the
emmetropization
• Only if beyond normal range for that age

24. Hyperopia upto 1 year
• Isohyperopia
– Error ≥ 2D & deviation present
• Prescribe the full cyclopegic correction
• Mandate frequent F/u if < 2 D
– Prescribe partial (2/3rd) if ≥ 5D
• Anisohyperopia
– < 2.5 D (No Rx if no deviation)
– ≥ 2.5
• Partial for no deviation
• Full Rx if esodeviation

25. Myopia upto 1 year
• Isomyopia < -5 D
– No Rx (Regular monitoring)
• Isomypia ≥ 5 D
– Rx with 1-2 D less
• Aniso-mypia ≥ 2.5 D
– Prescribe

26. Hyperopia in preschoolers
(upto 6 years)
• Isohyperopia
– Deviation present? Full Rx if error ≥ 1.5 D
– No deviation? Partial Rx (2/3rd) if ≥ 2.5 D
• Anisohyperopia
– < 1.5 ( No Rx, R/w 3 months)
– ≥1.5 D (partial for no deviation)
• Full for esodeviation

27. Myopia in Preschoolers
• Isomyopia < 3
– No Rx
• Isomyopia ≥ 3
– Prescribe but undercorrection
• Aniso-myopia ≥ 2D
– Prescribe

28. School Age
• Asymptomatic Isometropia ≥ 1.5  Prescribe
– Near full correction (emmetropization ended)
• Hyperopic anisometropia ≥ 1D
– Full correction
• Myopia?
– Optimum correction is warranted

29. Aphakic Correction
• Challenges
– High plus
– Astigmatism
– No accommodation
• Correction
– Overcorrect by 2-3 D in first few months
• Near consideration
– Decrease the overcorrection to 1-2D ≈1 year
• Intermediate distance consideration
– Bifocals in school age
• N+D consideration
Lawrence formula for aphakic correction,
P = +11 + half of pre-op error

30. Amblyopia
• Visual impairment without obvious organic
ocular pathology
– observer sees nothing and the patient very little
(Albrecht von Graeffe)
• Critical period
– Visual development permanently disrupted if
deprived of stimulation
– Age of neural plasticity
• Weeks of deprivation betn 3-6 months
• Months of deprivation below 8 years

31. causes
• Strabismus
– Constantly deviated eye amblyopic
• Refractive error & anisometropia
• Form deprivation
– Cataract/ptosis/corneal opacity

32. Amblyopia
• Most common cause
– Anisometropia (>1.5D)
• Anisohyperopia is more amblyogenic than anisomyopia
• Astigmatism
– Can’t be overcome by accommodation
• >1.5D is amblyogenic
• >1 D (>10o from90/180)
– Full cylinder correction recommended
• Myopia ≥ 3D
• Hyperopia ≥ 3.5

33. Strabismus
• Constancy
– Constant or intermittent
• Laterality
– Unilateral, alternate
• Horizontal deviation
– Exo or eso
• Vertical deviation
– Hypo or Hyper
• Comitancy
– Comitant or incomitant
• Cause
– Primary or secondary
• Age of onset
– Infantile or acquired

34. Esodeviation
1. Comitant Eso
A. Accommodative
• Refractive (normal AC/A)
• Non-refractive (High AC/A)
• Hypo-accommodative
• Partially accommodative
B. Non-accomodative
• Infantile (birth to 6 months)
• Acquired
– Basic
– Non accommodative convergence excess
– Esotropia in Myopia
– Acute esotropia
– Divergence insuffieciency
– Cyclic esotropia
C. Microtropia
D. Nystagmus Blockage Syndrome

35. 2. Incomitant Eso
A. Paralytic
B. Non paralytic or non-paretic
i. A and V pattern
ii. Retraction Syndromes
iii. Mechanical restrictive esodeviation
– Congenital fibrosis
– Acquired-restrictive (trauma, myopathy, surgery, etc)
3. Secondary Eso
A. Sensory
B. Consecutive

36. Exotropia
1. Infantile Exo
2. Acquired Exo
– Intermittent
– Acute
3. Microexotropia
4. Secondary Exo
– Sensory
– Consecutive

37. Nystagmus
• Involuntary, rhythmic, pendular or jerky
conjugate oscillation
– Congenital
– Acquired

38. Congenital Manifest Nystagmus
• First 3 months of life
• Cause
– Cataract
– Congenital glaucoma
– Aniridia
– Achromatopsia
– Down’s syndrome
– High Myopia
– Optic Nerve Hypoplasia
– Leber’s amaurosis
– OCA

39. Latent Vs Manifest-latent
• Latent
– Evoked by occluding one eye
– Absence when both eyes are open
• Manifest latent
– Latent nystagmus that gets evident at some gazes
– Is lesser in amplitude than the latent one
• Ocular Nystagmus
– Congenital (or with in 1st week ) ocular defects
• Spasmus Nutans
– 1st year of life and disappears 1-2 years
– High Frequency (7Hz), small amplitude
– Head nodding

40. • Sensory Defect Nystagmus
– Cause: inadequate image formation at fovea
– Anterior visual pathway disease
– Always B/L and horizontal
– Pendular and oscillates with equal velocity in both
direction
• Motor Defect
– Cause: efferent mechanism disruption
– Centers or pathways for oculomotor pathways
– Null Point: VA improved due to dampening of
Nystagmus

41. M. Optom First Batch @TIO (2019)