Donders Institute for Brain, Cognition and Behaviour
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Thesis defense Christine de Weger (Donders series 568)

18 October 2022

Promotor: Prof. dr. A.V. van den Berg
Copromotors: Dr. H.H.L.M. Goossens, Dr. F.N. Boonstra

Beyond improving visual acuity in children with Down syndrome. The effects of bifocals

Children with Down syndrome (DS) typically have reduced visual acuity and accommodative lag. Their development of visual, motor and cognitive functions is atypical and it is unknown whether the visual impairments in children with DS aggravate their delay in cognitive development. Therefore, in this thesis, the effects of bifocals (+2.5 dioptres in straight-top near addition placed at the pupillary centre) and unifocals, both with full correction of refractive error assessed in cycloplegia, in children with DS (n=104 aged 2 to 16 years) are compared in a multicentre (15) randomized controlled trial in the Netherlands with 1-year follow-up. We studied the effects of the interventions on visual acuity distant and near, uncrowded as well as crowded, accommodative accuracy, strabismus, and cognitive development (executive functions) and analysed possible correlations between these functions. After one year, wearing glasses with full correction for distant and near refractive errors (i.e. bifocals) had positive effects on distant visual acuity, near visual acuity (uncrowded and even more on crowded near vision), ocular alignment and executive function in children with DS, which suggests that there is indeed a link between visual and executive functioning. In conclusion, the prescription of bifocals (near addition +2.5 dioptres) with full correction of refractive error improves visual functions as well as educational and developmental prospects in children with DS.