Accommodation and refractive error in children with Down syndrome: Cross-sectional and longitudinal studies

PURPOSE. To examine the relationship between defective accommodation and re fractive errors in children with Down syndrome. METHODS. Children with Down syndrome aged 4 to 85 months were seen at their homes as part of an ongoing study of visual development. Seventy-five chil dren contributed cross-sectional data and 69 children longitudinal data. Ac commodation was measured using a modification of Nott dynamic retinoscopy t echnique, and refractive error measurements were obtained using Mohindra re tinoscopy. RESULTS. Accommodation was poor, regardless of the refractive error present . The total accommodation produced by the children was related to the refra ctive error at the time of the test, with the degree of accommodation defic it increasing with the amount of positive refractive error. The longitudina l results showed that although children with Down syndrome did not accommod ate accurately, the amount of accommodation elicited did not reflect their maximum amplitude of accommodation. Each child showed a consistent degree o f underaccommodation for a given stimulus. Spectacles to correct hypermetro pia did not improve the accommodative response. CONCLUSIONS. In children with Down syndrome, underaccommodation is substant ial, even when there is no, or a fully corrected, refractive error. The acc ommodation system of children with Down syndrome may have the physical capa city to respond to a given stimulus, but the neural control of the system h as an anomalous set point. Spectacles do not remedy the situation. This has important implications, especially for children in a learning environment, because near vision is consistently out of focus.