title: Effects of magnifier training: evidence from a camera built in the magnifier.
abstract: OBJECTIVE
  This study evaluated the effect of an evidence-based magnifier training on viewing behavior in visually impaired children aged 3 to 6½ years.
  
  
  METHODS
  Effects of a training with a stand magnifier were evaluated by analyzing recordings of 21 visually impaired children, obtained from a miniature camera mounted in the magnifier. In a pre-test, post-test design, 11 of the children trained without magnifier and 10 children trained with magnifier. Three measures were compared from pre- to post-test assessment: 1) observation time in seconds through the magnifier during task performance; 2) the eye that was used during task performance with the magnifier (right eye/left eye as recorded by the camera); and 3) the self-chosen eye-to-chart distance (in cm) in near visual acuity measurement.
  
  
  RESULTS
  Three important changes were found by analyzing the eye-camera recordings: (1) There was a significant shift in average observation time (i.e., the duration of looking through the magnifier in a single glance), before and after training. In the pre-test children used less than 10 s for a glance through the magnifier, whereas in the post-test this was 10-30 s. (2) In 5 children there was no preference with respect to the number of glances through the magnifier with right or left eye during pre-test measurement. However, such a task-specific dominance was clearly observed in this subgroup after training (post-test measurement). (3) The eye-to-chart distance, as measured during near-vision testing with LH-single and LH-line test, decreased significantly over the training period (from 9.5 cm to 7.9 cm, pre- to post-test). There were no differences in the outcome measures between the with-magnifier and without-magnifier training groups. We can conclude that (1) the magnifier training had a positive effect on viewing behavior and the development of dominance, and (2) camera observations provide valuable data on children's viewing behavior.
authors.affiliation: Bartiméus Institute for the Visually Impaired, Zeist, The Netherlands. nboonstra@bartimeus.nl
authors.forename: F Nienke
authors.initials: FN
authors.lastname: Boonstra
authors.forename: Ralf F A
authors.initials: RF
authors.lastname: Cox
authors.forename: Annemieke M
authors.initials: AM
authors.lastname: Reimer
authors.forename: Cornelis A
authors.initials: CA
authors.lastname: Verezen
authors.forename: Piet
authors.initials: P
authors.lastname: Rison
authors.forename: Bianca
authors.initials: B
authors.lastname: Huurneman
mesh_terms: D001296:Audiovisual Aids; D002648:Child; D002652:Child Behavior; D002675:Child, Preschool; D023882:Dominance, Ocular / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010781:Photography / Q000295:instrumentation*; D012682:Sensory Aids; D013647:Task Performance and Analysis; D014741:Video Recording; D015354:Vision, Low / Q000523:psychology / Q000534:rehabilitation*; D014792:Visual Acuity / Q000502:physiology; D019987:Persons with Visual Disabilities / Q000523:psychology / Q000534:rehabilitation*