Why do Children with Down Syndrome Have Subnormal Vision?

Abstract

People with Down syndrome have a wide variation in visual acuity, but generally 20 / 40 or worse. Both the eye and brain tend to be different in these patients compared to age matched normal subjects. Also, accommodative insufficiency (determined by dynamic retinoscopy) is often present in children Down syndrome, making bifocals a necessary consideration.

Effects of bifocals on visual acuity in children with Down syndrome: a randomized controlled trial

“…In literature, the following prevalences have been reported: reduced visual acuity (poorer than 0.3 LogMar) in 80–100% and poor contrast sensitivity in almost all DS children (John et al. ; Morton ; Little et al. ; Watt et al.…”

“…Their brain development differs from typically developing children. In particular, in children with DS less brain weight is found, there is dendritic atrophy, and poor maturation of the central nervous system has been described (Courage et al 1994;Little et al 2009a, Morton 2011Watt et al 2015). In recent years, research has shown that their visuospatial memory is better than their verbal memory (Lanfranchi et al 2004;Frenkel & Bourdin 2009).…”

“…Compared to other children, many ocular findings in DS occur more frequently and in a more severe form (Creavin & Brown 2009;Little et al 2009b, Afifi et al 2013Aslan et al 2014;Watt et al 2015). In literature, the following prevalences have been reported: reduced visual acuity (poorer than 0.3 LogMar) in 80-100% and poor contrast sensitivity in almost all DS children (John et al 2004;Morton 2011;Little et al 2013;Watt et al 2015;Zahidi et al 2018). Accommodation deficit occurs in 50-90% of the children with DS (Woodhouse et al 1993(Woodhouse et al , 1996(Woodhouse et al , 2000Cregg et al 2001;Nandakumar & Leat 2009Anderson et al 2011;Doyle et al 2016Doyle et al , 2017.…”

“…Children with DS who initially have no refraction error are at risk of developing refraction errors. Furthermore, the prevalence of strabismus in DS is 15-47% Cregg et al 2003;Stewart et al 2007;Ljubic et al 2011;Morton 2011;Watt et al 2015;Doyle et al 2016), which is on average 10 times higher than in normally developing children (Bruce & Santorelli 2016;Schuster et al 2017). In DS, the onset of strabismus occurs mostly between 3 and 6 years of age.…”

Cataract surgery outcomes in adult patients with Down's syndrome: Table 1

“…We were unable to assess the exact role of an amblyopic component in our patients, but there is a possibility that some of the patients did not attain good vision postoperatively due to amblyopia 28. It has also been suggested that individuals with Down's syndrome may have a wide variation in visual acuity due to differential characteristics between the eye and the brain29 and other associated neuropathologies 30. Also, as mentioned previously, it may be difficult to accurately assess the visual function and visual acuity in these patients due to subnormal mental intelligence.…”