Visual acuity and accommodation in infants and young children with Down's syndrome.

Accommodation and visual acuity were measured in 53 children with Down's syndrome aged between 12 weeks and 57 months. Results were compared with data for 136 control (typically developing) children aged between 4 weeks and 48 months. Whereas the control children accommodated accurately on near targets, accommodation was defective in 92% of the children with Down's syndrome, and there was no change in accommodative ability with age. On the other hand, visual acuity lay within normal limits for the younger children. Children over the age of 2 years showed a below-normal visual acuity, which is not explained either by refractive error or by the effect of poor accommodation. The data suggest a sudden change in the rate of development of visual acuity which may be associated with physiological changes in the visual cortex. Previously reported defects of accommodation and visual acuity in older children and adults with Down's syndrome are confirmed by our findings in infants and young children.