Down's syndrome: vision, visual problems and visual assessment
Presented on 15 May 2008
J. Margaret Woodhouse, Cardiff University
Mohammad Al-Bagdady, Nathan
Bromham, Mary Cregg,
Ping Ji, Ffion John, Julie-Anne Little, Julie McClelland,
Val Pakeman, Kathryn J. Saunders, Ruth Stewart
Visual / ocular defects in children with Down's syndrome
- Refractive errors (60%)
- Poor accommodation (80%)
- Squint (25%)
- Nystagmus (15%)
- Blepharitis (up to 50%)
- Cataracts (8-13%)
- Keratoconus (15%)
- Reduced visual acuity and contrast sensitivity (100%)
Down’s syndrome – Cardiff study
- cohort first established in 1992, ongoing recruitment
- current cohort = 180+, ages 2 months to 18 years
- longitudinal monitoring and lab-based studies
http://www.cardiff.ac.uk/optom/DownsSyndromeGroup/Home.html
The lens
Accommodation
Accommodation reduces consistently with age
Short sight (myopia)
A short-sighted child
- Will have clear vision at near and blurred vision at distance.
- Will need to wear glasses for distance.
- May choose to wear glasses all the time.
- May use eyes 'natural magnification' by removing specs for near focus.
Long sight (hypermetropia)
By accommodating, we can overcome small amounts of long sight.
A long-sighted child
- Will have clearer vision at distance and more blurred or uncomfortable vision at near. Extent of blur or discomfort will depend on age as well as amount of long-sight.
- May need to wear glasses for near.
- May need to wear glasses all the time.
Astigmatism
A child with astigmatism
- Will have blurred vision at all distances.
- May need to wear glasses for both distance and near.
- May find adjusting to the glasses very difficult.
Measuring long and short-sight - Refraction
retinoscopy
The prescription
Lenses to correct myopia (short-sight) are negative eg;
-5.00D, -7.50D
Lenses to correct hypermetropia (long-sight) are positive eg; + 2.25D,
+6.75D
The astigmatic (cylindrical) component of the lens is the second figure
of the prescription, and the direction of the astigmatism the third part
eg; -1.00 / +0.50 x 90, +3.50 / - 1.25 x 45
Typical children
Children with Down's Syndrome
Emmetropisation
Children with Down's Syndrome
Long sight and short sight are associated with eye length in DS in the same way as for typical children.
When to prescribe?
- Typical children outgrow 'baby' errors – it seems sensible to allow time for errors to decrease
- Children with DS do not outgrow 'baby' errors – prescribe at younger ages?
Wearing glasses
Children with Down's syndrome have differently shaped faces to 'ordinary' children. Ensure specs fit well.
Getting used to glasses
- Children with disabilities often find new situations difficult
- Glasses give clearer vision – to a child that means 'different'
- Build up wearing time gradually