title: Bifocals in children with Down syndrome (BiDS) - visual acuity, accommodation and early literacy skills.
abstract: OBJECTIVE
  Reduced accommodation is seen in children and young adults with Down syndrome (DS), yet providing bifocals has not become a routine clinical management. This study investigates the impact of bifocals on visual function, visual perceptual and early literacy skills in a group of school children with DS.
  
  
  METHODS
  In this longitudinal study, each child was followed for 5months with single-vision (SV) lenses after which bifocals were prescribed if required, based on their accommodative response. Visual acuity (VA), accommodation, perceptual and literacy skills were measured after adaptation to bifocals and 5months later. Educational progress and compliance with spectacle wear were assessed through school and parental reports.
  
  
  RESULTS
  Fourteen children and young adults with DS participated in the study. Eighty-five percent required bifocals with additions ranging from +1.00D to +3.50D. The mean near logMAR VA improved with bifocals (p=0.007) compared to SV lenses. Repeated measures anova showed that there was more accurate focus (less accommodative lag) through the bifocals (p=0.002), but no change in the accommodation exerted through the distance portion compared to SV lenses (p=0.423). There was a main effect of time on sight words (p=0.013), Word Identification (p=0.047), Visual Closure (p=0.006) and Visual Form Constancy (p=0.001).
  
  
  CONCLUSIONS
  Bifocals provide clearer near vision in DS children with reduced accommodation. This is shown by improved VA and decreased lag of accommodation. The results indicate that the improvement in VA results in improved scores in early literacy skills. Better compliance with bifocals over SV lenses was seen.
authors.affiliation: School of Optometry, University of Waterloo, Ontario, Canada. k2nandak@uwaterloo.ca
authors.forename: Krithika
authors.initials: K
authors.lastname: Nandakumar
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Leat
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D004314:Down Syndrome / Q000503:physiopathology / Q000534:rehabilitation*; D004522:Educational Status; D005139:Eyeglasses; D006801:Humans; D011932:Reading; D014786:Vision Disorders / Q000503:physiopathology / Q000534:rehabilitation*; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology