Download Visual Impairment The paediatricians perspective

Vision
The Paediatricians perspective
Dr Sneha Sadani
Dr Gill Robinson
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Normal vision
Visual history
Examining eyes
Assessing Vision
Abnormalities of eye movement
Squint
nystagmus
Normal vision development
• Newborns can see, VA 20/400 ( 20 feet= 6 m)
– Fixate on lights, points of contrast
• Earliest response to formed visual stimulus- regard
for mum’s face
• 2 weeks, sustained interest in large objects
• 8-10 weeks follows object through 180°
• Proper co ordination of eye movements +
alignement-3 to 6 mo
• VA continues to improve
– 20/40 by 3 yrs
– 20/30 by 4 yrs
– 20/20 by 5-6 yrs
Newborns
look at light
source
Early weeks of life fix on human face
8-10 weeks
follows object
through 180°
3 months hand
regard ... And
together in
midline
Proper
coordination of
eye movements +
alignment at 3 to
6 months
Seeing to play
12 months point
at distant object
2 to 3 years
3 to 4 years
4 to 5 years
Visual History
• Do you have any concerns about eyes?
• Do you think she sees normally? Why/why not?
• Does she look at your face?
• Does she watch as you walk away?
• What sort of things can she see?
• Bits of fluff on the carpet
• Airplane high in the sky
Visual History
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Recognizing faces (not voices)
Does she look at toys/pictures?
Does she hold objects close to her eyes?
Does she feel for objects?
Have you seen either eye turning in or out?
PMH
Are there other disabilities?
FH
Is there a family history of eye problems?
Examination
• General
– Dysmorphology, albinism
– OFC
– Look for head tilt and abnormal gaze which can be
due to field defects or squint.
• Eyes
– size, shape, symmetry
– Lids, sclera, iris, pupil
Examination
• Ocular Motility (Abnormal eye movements)
– at rest
– tracking - following torch through horizontal and
vertical axis.
• Alignment (Squint)
– Corneal reflections in all positions of gaze
– Cover test – more later
Examination
• Red reflex
• Ophthalmoscopy
• Visual fields – by confrontation
• Functional visual assessment
• Visual acuity test
• Colour vision testing
Visual acuity tests
Age
• Birth
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• 6 weeks
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• 6 months
• 2 yrs
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• 3 yrs
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• 5 yrs +
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Test
Face fixation & following, preferential
looking (patterned objects)
Optokinetic nystagmus demonstrated on
looking at a moving striped target
Reaches well for toys
Identifies specific pictures of reducing
size (Kays or crowded Kays)
Letter matching using single letter
charts
Line of letters on Snellen / logmar chart
by naming or matching
Functional visual assessment – older child
• What objects can a child identify near or in the
distance
• Use books to observe the way the child looks at
a picture –
• Do they hold books up close.
• What type of pictures can child identify near
and in the distance.
Note familiar objects and pictures will be
recognized more readily than unfamiliar.
Red reflex
Squint / strabismus
Corneal light reflex test
Overt squint
Cover the bad eye – nothing
happens
Cover the good eye – the bad
eye moves in to take up fixation
Latent squint – don’t worry these don’t come
to the exam
Amblyopia
Preferential looking
• Infants dislike boring visual stimuli
• You present a display to a baby, half of which is
quite plain and the other have has some pattern
to it, the baby will tend to look at the pattern
• Grating patterns of different widths
• An observer has to decide, based on their
observation of the baby's head and eye
movements, where the stimulus is located.
Kay pictures
• Verbal/matching
abilities (2 years +)
• Single and Crowded
format
• 12 equal step sizes
Crowded Kays
• Simple and quick – 3
years+
• At 3m ask the child to
read all the pictures in
one vertical row down
to smallest size. Can
also use matching card
• Correlates to logamar
and snellen
• screening pass criteria
of 0.200 (3/4.8 or 10/16
Snellen) instructions.
Snellen
Logmar
Snellen
• Numerator- distance from
chart i.e. 6m/20 feet
• Denominator – distance
at which a person with
good vision could read
the last line that the
patient is able to read
Logmar
• logarithm of the minimum
angle of resolution
• One feature seen on
snellen
• LogMAR scale converts
the geometric sequence
of a traditional chart to a
linear scale.
Comparison of Snellen and Logmar
Metre
6/60
6/48
6/36
6/24
6/18
6/15
6/12
6/9
6/7.5
6/6
6/4.8
6/3
LogMAR
1.00
0.90
0.78
0.60
0.48
0.40
0.30
0.18
0.10
0.00
-0.10
-0.30
Poorer than normal
Normal
Better than normal
Testing colour vision
Common problems
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1 in 10 at risk from undiagnosed vision problems
1 in 30 children will be affected by amblyopia
1 in 25 will develop strabismus
1 in 33 will show significant refractive error such
as nearsightedness, farsightedness and
astigmatism
• 1 in 100 will exhibit evidence of eye disease – e.g.
glaucoma
• 1 in 20,000 children have retinoblastoma
Strabismus
Causes of squint
Normal until 3 months of age
• Paralytic
• Squint varies with
position of gaze
• III, IV, VI
• Strabismus syndromes
• Non paralytic
• Squint present in all
positions of gaze
• Genetic
• Refractive error
• Ocular abnormalities –
cataract,
neuroblastoma
III nerve palsy
• Usually congenital,
ominous if acquired
• Superior, inferior and
medial recti and
inferior oblique
• Ptosis
• Double vision in all
positions of gaze
• Pupil may be dilated
and unresponsive
• IV nerve palsy
– Superior oblique
– Vertical separation
images
– Worse looking down
and in
– Traumatic or congenital
• VI nerve Palsy
– Lateral rectus
– Horizontal diplopia
worse on looking to the
side of the lesion
– Due to birth trauma
Nystagmus
• Involuntary rhythmic, conjugate oscillatory
movements of one or both eyes
• Complex!
• Congenital
– Pendular
– Idiopathic motor
• Gaze evoked
• Vestibular – fast jerk in direction of lesion
• BEWARE ROVING EYE MOVEMENTS OF
BLIND CHILD
Congenital Nystagmus
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Seen shortly after birth
Binocular
Similar amplitude both eyes
Usually horizontal
Abolished by sleep
Genetic component inc albinism
What is the diagnosis?
Name 3 causes
What test would you like
to do?
Ptosis – congential and acquired
• Congenital
– Absence of levator palpebrae – beware vision
– Mostly unilateral
– May be familial and acquired causes of ptosis
• Acquired
– 3rd nerve palsy – trauma, tumour, post meningitis
– Myasthenia gravis
Tensilon test
• IV endrophonium
chloride
• (infant 1mg - child
8mg)
• Photos before and
after
• Dramatic improvement
1 min
• Lost by 5 mins
Visual Impairment
-WHO definitions.
These definitions are based on best corrected vision in the better eye.
Normal vision
6/18 or better (slight VI <6/9)
Visual impairment 6/18 – 6/30
Low vision
<6/30 – 6/60
Severe VI/Blind
<3/60 to no light perception
(cannot count fingers at 3m)
Or fields <10°around central
fixation
Prevalence (/10,000 children)
Age
Just VI
VI +
All
1
0.9
3.2
4.1
5
1.1
4.2
5.3
16
1.3
4.6
5.9
Severe visual impairment and blindness in children in the UK,
RahiJS, Cable N, The Lancet, 362,1359, 2003
In Leeds 260 children
Regardless of cause VI affects
development
How does VI affect development?
• Self help
Mummy needs to move closer
Communication
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Early bonding
Socialisation
Struggle with joint attention
Struggle to change between tasks
Vocalisation
• 2 to 3 words – 19/12 cf 14/12
• Name 2 objects – 2 years cf
15/12
Behaviour / social interaction
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Struggle with joint attention
Struggle to change between tasks
Tendency to repetative play
Echolalia
Tantrums
Resistance to change
Sleep
Severe VI 17-42% autism
Body awareness
Hand awareness
We need mobility for movement and
navigation
Environment awareness
Concept development
We need vision to learn
Self help and independance
Examine Eyes
• General
• Eyes
– size, shape, symmetry
– Lids, sclera, iris, pupil
• Ocular Motility (Abnormal eye movements)
– at rest / tracking
• Alignment (Squint)
– Corneal reflections / Cover test
• Red reflex /Ophthalmoscopy
• Visual fields – by confrontation
Assess vision
• Functional visual assessment
• Visual acuity test
• Colour vision testing