In a longitudinal project, (originally supported by the Down's Syndrome Association and currently by the Medical Research Council), we have recruited young children with Down's Syndrome throughout the counties of South and West Wales, and monitored visual development alongside cognitive development. Ocular/Visual measurements include visual acuity by Preferential Looking techniques. Cognitive development is monitored by the Bayley Scales of Infant Development. All measurements are taken during home visits. Visual acuity lies within the normal range for all of our younger children under the age of around 2 years. After this, some children fail to show a further improvement, so that acuity falls below the normal range (as the normal acuity range improves) at a later date. At the present time, we are able to divide the children (for whom we have longitudinal data from an early age), into those whose visual acuity remains normal and those whose visual acuity is below normal. There is a significant difference in cognitive performance between the two groups. Those children with normal acuity are cognitively more able (mean Bayley scores) at the last time of testing than the children whose acuity is below normal. Our findings suggest that visual acuity may be reflecting global cortical defecits in young children with Down's Syndrome, and, since it is a quick and repeatable measure, may prove useful in monitoring cognitive changes under, for example, intervention programmes.
Collaborators: Mary Cregg, Margaret Parker, Helen Gunter, Val Pakeman: Optometry & Vision Sciences, UWC, Cardiff, Bill Fraser, Welsh Centre for Learning Disability, UWCM, Cardiff, Prema Sastry, Community Health Unit, Cardiff