Visual Considerations for children with Down

syndrome and Cerebral Palsy

Julie-Anne LittleVIEW conference, March 2013

Julie-Anne Little PhD MCOptom ja.little@ulster.ac.uk

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

< -0.50DC

ControlGroup(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’

Summary

1. 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

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 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?