title: Accommodation and refractive error in children with Down syndrome: cross-sectional and longitudinal studies.
abstract: OBJECTIVE
  To examine the relationship between defective accommodation and refractive 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 children contributed cross-sectional data and 69 children longitudinal data. Accommodation was measured using a modification of Nott dynamic retinoscopy technique, and refractive error measurements were obtained using Mohindra retinoscopy.
  
  
  RESULTS
  Accommodation was poor, regardless of the refractive error present. The total accommodation produced by the children was related to the refractive error at the time of the test, with the degree of accommodation deficit increasing with the amount of positive refractive error. The longitudinal results showed that although children with Down syndrome did not accommodate accurately, the amount of accommodation elicited did not reflect their maximum amplitude of accommodation. Each child showed a consistent degree of underaccommodation for a given stimulus. Spectacles to correct hypermetropia did not improve the accommodative response.
  
  
  CONCLUSIONS
  In children with Down syndrome, underaccommodation is substantial, even when there is no, or a fully corrected, refractive error. The accommodation system of children with Down syndrome may have the physical capacity to respond to a given stimulus, but the neural control of the system has 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.
authors.affiliation: Department of Optometry and Vision Sciences, Cardiff University, Wales, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Cregg
authors.forename: J M
authors.initials: JM
authors.lastname: Woodhouse
authors.forename: V H
authors.initials: VH
authors.lastname: Pakeman
authors.forename: K J
authors.initials: KJ
authors.lastname: Saunders
authors.forename: H L
authors.initials: HL
authors.lastname: Gunter
authors.forename: M
authors.initials: M
authors.lastname: Parker
authors.forename: W I
authors.initials: WI
authors.lastname: Fraser
authors.forename: P
authors.initials: P
authors.lastname: Sastry
mesh_terms: D000065:Accommodation, Ocular; D000375:Aging / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004314:Down Syndrome / Q000150:complications* / Q000503:physiopathology; D005139:Eyeglasses; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D012030:Refractive Errors / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D014786:Vision Disorders / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D014787:Vision Tests