title: Effective and Efficient Stand Magnifier Use in Visually Impaired Children.
abstract: OBJECTIVE
  The main objective of this study was to analyze the effectiveness and efficiency of magnifier use in children with visual impairment who did not use a low vision aid earlier, in an ecologically valid goal-directed perceptuomotor task.
  
  
  METHODS
  Participants were twenty-nine 4- to 8-year-old children with visual impairment and 47 age-matched children with normal vision. After seeing a first symbol (an Lea Hyvärinen [LH] symbol), children were instructed to (1) move the stand magnifier as quickly as possible toward a small target symbol (another LH symbol that could only be seen by using the magnifier), (2) compare the two symbols, and (3) move the magnifier to one of two response areas to indicate whether the two symbols were identical. Performance was measured in terms of accuracy, response time, identification time, and movement time. Viewing distance, as well as hand and eye dominance while using the magnifier was assessed.
  
  
  RESULTS
  There were no significant differences between the two groups in accuracy, reaction time, and movement time. Contrary to the prediction, children with visual impairment required less time to identify small symbols than children with normal vision. Both within-subject and between-subject variability in viewing distance were smaller in the visually impaired group than in the normally sighted group. In the visually impaired group, a larger viewing distance was associated with shorter identification time, which in turn was associated with higher accuracy. In the normally sighted group, a faster movement with the magnifier and a faster identification were associated with increasing age.
  
  
  CONCLUSIONS
  The findings indicate that children with visual impairment can use the stand magnifier adequately and efficiently. The normally sighted children show an age-related development in movement time and identification time and show more variability in viewing distance, which is not found in visually impaired children. Visually impaired children seem to choose a standard but less adaptive strategy in which they primarily used their preferred hand to manipulate the magnifier and their preferred eye to identify the symbol.
  
  
  BACKGROUND
  Registered at http://www.trialregister.nl; NTR2380.
authors.affiliation: Behavioural Science Institute, Radboud UniversityNijmegen, Netherlands; Bartiméus Institute for the Visually ImpairedZeist, Netherlands; Expertise Center Health, Social Care and Technology, Saxion University of Applied SciencesEnschede, Netherlands.
authors.forename: Joyce
authors.initials: J
authors.lastname: Liebrand-Schurink
authors.affiliation: Department of Psychology, University of Groningen Groningen, Netherlands.
authors.forename: Ralf F A
authors.initials: RF
authors.lastname: Cox
authors.affiliation: VU University Medical Center Amsterdam, Netherlands.
authors.forename: Ger H M B
authors.initials: GH
authors.lastname: van Rens
authors.affiliation: Behavioural Science Institute, Radboud University Nijmegen, Netherlands.
authors.forename: Antonius H N
authors.initials: AH
authors.lastname: Cillessen
authors.affiliation: Department Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre Nijmegen, Netherlands.
authors.forename: Ruud G J
authors.initials: RG
authors.lastname: Meulenbroek
authors.affiliation: Bartiméus Institute for the Visually ImpairedZeist, Netherlands; Department Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical CentreNijmegen, Netherlands.
authors.forename: Frouke N
authors.initials: FN
authors.lastname: Boonstra
keywords: fine motor skills; low vision; magnifier; motor development; perceptuomotor task; visually impaired children