Visual Considerations for children with Down syndrome and

Report
Visual Considerations for
children with Down
syndrome and Cerebral
Palsy
Julie-Anne Little
VIEW conference, March 2013
Julie-Anne Little PhD MCOptom [email protected]
Summary of talk
 Synopsis of Down syndrome & Cerebral
Palsy
 Key Visual Problems:
1. Refractive error
2. Accommodation
3. Visual acuity
4. Visual Field
5. Crowding & complexity
Summary of talk
 Summary
-Take home messages
 Practical strategies
Down syndrome
 Most common genetically based cause of learning
disability
 Prevalence: 1 in 600-800 live births
 Prevalence increasing?
 Increasing maternal age increases risk
70-fold increased risk of DS in mothers over 45 years of age
 Approximately half infants with DS born with
associated conditions
Down syndrome
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Heart defects
Leukaemia
Thyroid problems
Hearing problems
Accelerated ageing
Alzheimer's
Cataract
 Learning difficulties – delayed development
Visual problems in Down syndrome
 Frequent need for glasses (High refractive errors)
 Focussing problems (Accommodation)
 Reduced Vision (Visual acuity)
Visual problems in Down syndrome
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Cataracts
Squints (Strabismus)
Lazy eye (Amblyopia)
Nystagmus
Keratoconus
Congenital glaucoma
Blepharitis
CVI
Cerebral Palsy
 Cerebral Palsy (CP) affects 2-3 in 1000 live
births
 CP is the most common cause of physical
disability in children
Cerebral Palsy classifications
1. By Motor impairment:
 Gross Motor Function Classification Scale
(GMFCS)
• Grade 1 ‘Walks without limitations’
to Grade V ‘uses a wheelchair’
 ‘Hemiplegia’, ‘Diplegia’, ‘Tetraplegia’,
‘Quadraplegia’
2. By Subtype:
Spastic, Dyskinetic & Ataxic
Visual problems in Cerebral Palsy
 Frequent need for glasses (High refractive
errors)
 Focussing problems (Accommodation)
 Reduced Visual acuity
 Visual field restrictions
Visual problems in Cerebral Palsy
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Squints (Strabismus)
Lazy eye (Amblyopia)
Nystagmus
Optic Atrophy
CVI
Retinopathy of Prematurity
Typical Visual development
 There is a natural time course for visual
development
 Need for glasses, reduced vision, a ‘lazy eye’
and/or squints can occur if visual development
doesn’t perfectly occur
 Premature infants have increased risk of visual
problems
 Increased prevalence of visual impairment
among those with learning disability (up to
28%) (Warburg, 2001)
Need for spectacles
R +2.25 / -2.00 * 180
L +1.75 / -1.50 * 170
 Called Refractive error
#1 Spherical Part
Myopia
Short-sighted
Minus numbers
e.g. -2.50D,
-6.25D
#2 Cylindrical
part
Hypermetropia
or Hyperopia
Long-sighted
Plus numbers
e.g. +1.75D,
+5.75D
Astigmatism
Oval or ‘rugby
ball’ shaped eye
(cornea)
Cylindrical or
toric lenses
Number & Axis
written after
‘Spherical’ part
Moderate values
+/-2.00 to 4.00D
High values
Greater than
+/-5.00
Moderate value
/ -1.50DC *α
High values
greater than
/ -2.50DC *α
Refractive error Examples
R +6.25 / -0.50 * 90
L +6.75 / -0.50 * 85
R - 7.75
L – 7.25
R +0.25 / -0.50 * 180
L +0.50 / -0.50 * 175
R -1.25 / -2.00 * 50
L -1.75 / -2.00 * 135
R +4.25
L +4.00
DS Refractive error
 Several Studies reporting high refractive
errors in DS (Woodhouse et al, Haugen et al)
Mean
Refractive
error
Significant
Refractive
Error
Myopia
≤ -0.50DS
Hyperopia
≥ +2.50DS
Control
Group
(n=68)
-0.46
28%
25%
1%
6%
DS Group
(n=29)
+2.52
59%
10%
48%
41%
Aged 9-16
years
Astigmatis
m
< -0.50DC
Little, Woodhouse & Saunders, 2009
DS Refractive error
 Astigmatism common, related to corneal shape
 More commonly oblique
 Cornea thinner and steeper
CP Refractive error
 Moderate/High refractive errors are common in CP
75% (Fazzi et al. 2012)
72% (Saunders, Little et al 2010)
Vision aka Visual Acuity
 Vision improves and refines from infancy to
approx age 7 years
 By school age, children should have “20-20
vision” (6/6, 0.0logMAR)
 There are several ways to measure vision
 Nice to measure vision in each eye separately
Visual Acuity in DS & CP
 Several studies have reported reduced visual acuity in
Down syndrome and Cerebral palsy.
Controls:
- 0.06logMAR
CP: +0.18 logMAR
(blue squares)
DS: +0.39 logMAR
(red triangles)
Little et al 2012
Focussing (Accommodation)
 Accommodation is the focussing ability of the
eye.
 We change our focus when looking at objects at
different distances
 Natural decline with age.....
Accommodation in DS & CP
 67-75% of people with Down syndrome exhibit
reduction in ability to accommodate
 58% of people with CP
 Study found that those with CP that have higher
levels of motor impairment (by GMFCS) are
more likely to have problems with focussing
Accommodation in DS & CP
 Side effect of medications can reduce ability to
focus e.g. Hyoscine patches
 Need to check they have the full strength in their
glasses
 Bifocals commonly given to
ensure good vision for near work
 Alternative is second pair
of glasses for reading
Visual Fields
 Normal visual field 90-100° either side and about
60° above & 75° below
 Possible Visual field loss/neglect with brain
damage
Visual Field problems in CP
 Recent study found majority (62%) of children with
CP with mild motor impairment (Level 1 on GMFCS)
had some reduction in their visual fields
 1 in 5 of these children revealed as having severe
visual field restriction (Jacobson et al. 2010)
Crowding & Complexity
 Process of seeing involves the eyes sending the
visual information they acquire to the brain;
 Brain processes image and evaluates the
important things in the image using visual
memory and discrimination
 CVI
Summary
 Vision is important!
 Knowledge of vision and how a child sees
relevant to daily life
 People with DS have poorer auditory memory
and are more successful ‘visual learners’
Summary
1. Those with CP and DS more likely to need
glasses
For every child we need to understand the
importance of spectacles to them and when
they should be used. Are they kept clean and
fitted appropriately?
2. Likely to have focussing problems
Child may have bifocals or two pairs of glasses
Summary
3. Those with DS or severe CP likely to have
reduced vision
We need knowledge about vision to ensure
visual material of the appropriate size, detail &
contrast at a suitable distance is provided
4. Remember visual fields and crowding!
If a child has problems seeing all around them
this could impact on their mobility and
orientation skills. Avoid overwhelming with too
many objects or too much material at one time
Food for thought
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Any concerns about vision?
Has child had a visual assessment?
What do we know about child’s vision?
How can we maximise visual and learning
experience of the child?
 Why does child wear glasses? Are they fitting
well?
 Is educational/recreational material bright, bold
and clear enough for child?
 Is room lighting appropriate and child’s position
in room appropriate?
Food for thought
 Does the child have difficulties processing visual
information?
 Does the child like to interact in a tactile way?
 Can the child locate work items easily?
 Could any of the child’s behaviour be related to
their visual status?

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