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 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 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 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 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?