Julie-Anne Little PhD MCOptom [email protected]
description
Transcript of Julie-Anne Little PhD MCOptom [email protected]
Visual Considerations for children with Down
syndrome and Cerebral Palsy
Julie-Anne LittleVIEW conference, March 2013
Julie-Anne Little PhD MCOptom [email protected]
Summary of talk Synopsis of Down syndrome & Cerebral
Palsy
Key Visual Problems:1. Refractive error2. Accommodation3. Visual acuity4. Visual Field5. 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 Heart defects Leukaemia Thyroid problems Hearing problems Accelerated ageing
Alzheimer'sCataract
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 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 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 Called Refractive error
#1 Spherical Part
Myopia Short-sighted Minus numberse.g. -2.50D,
-6.25D
Moderate values +/-2.00 to 4.00D
High valuesGreater than
+/-5.00Hypermetropiaor Hyperopia
Long-sighted Plus numbers e.g. +1.75D,
+5.75D
#2 Cylindrical part
Astigmatism Oval or ‘rugby ball’ shaped eye
(cornea)
Cylindrical ortoric lenses
Number & Axiswritten after
‘Spherical’ part
Moderate value / -1.50DC *αHigh values greater than
/ -2.50DC *α
R +2.25 / -2.00 * 180L +1.75 / -1.50 * 170
Spherical
Cylindrical
Refractive error Examples
R +6.25 / -0.50 * 90L +6.75 / -0.50 * 85
R - 7.75L – 7.25
R -1.25 / -2.00 * 50L -1.75 / -2.00 * 135
R +0.25 / -0.50 * 180L +0.50 / -0.50 * 175
R +4.25L +4.00
DS Refractive error Several Studies reporting high refractive
errors in DS (Woodhouse et al, Haugen et al)
Aged 9-16 years
Mean Refractive
error
SignificantRefractive
Error
Myopia ≤ -0.50DS
Hyperopia ≥ +2.50DS
Astigmatism
< -0.50DCControlGroup(n=68)
-0.46 28% 25% 1% 6%
DS Group(n=29)
+2.52 59% 10% 48% 41%
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 CP75% (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:
- 0.06logMARCP: +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’
Summary1. Those with CP and DS more likely to need
glassesFor 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
Summary3. 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 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?