title: Influence of Near Tasks on Posture in Myopic Chinese Schoolchildren.
abstract: OBJECTIVE
  To investigate near-vision posture in Chinese myopic schoolchildren and compare near-vision posture during different near-vision tasks (i.e., playing video games, reading, and writing).
  
  
  METHODS
  The study investigated 120 myopic children (grades 1 through 6 and aged 6 to 13 years). An electromagnetic motion-tracking system was used for continuous measurements of the working distance and head declination of the subjects while they were playing video games or reading or writing at a desk. The reading and writing documents were adjusted by grade level (i.e., grades 1 to 2, 3 to 4, and 5 to 6). For analysis, the subjects were grouped in two refractive groups according to their median spherical equivalent refractive error (-1.50D).
  
  
  RESULTS
  The myopic schoolchildren used close working distances for all tasks: 21.3 ± 5.2 cm (video games), 27.2 ± 6.4 cm (reading), and 24.9 ± 5.8 cm (writing). The mean head declinations were 63.5 ± 12.2 deg (video games), 37.1 ± 12.8 deg (reading), and 44.5 ± 14.1 deg (writing). Working distance decreased significantly across time for the reading and writing tasks (p < 0.001). Head declination increased significantly across time only for the reading task (p < 0.001). Grade level significantly influenced working distance, but the difference was not significant when working distance was adjusted by the subject's size. No differences were observed within the refractive or the accommodative lag groups in terms of the posture data (p > 0.05). Working distance was negatively correlated with head declination (r = -0.53, p < 0.001).
  
  
  CONCLUSIONS
  Close working distances were observed for Chinese myopic schoolchildren. The attention dedicated to each task, the task difficulty, and the page/screen size may affect near working distance and head declination. Handheld video games were associated with the closest working distance, which may be a risk factor for myopia progression, according to previous studies.
authors.affiliation: *MSc †PhD ‡MD §BOptom ∥MD, OD School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China (JHB, YWW, KC, FL); R&D Asia, Essilor International, Singapore (BD, EJS); and Wenzhou Medical University-Essilor International Research Centre, Wenzhou, Zhejiang, China (JHB, BD, YWW, KC, FL).
authors.forename: Jinhua
authors.initials: J
authors.lastname: Bao
authors.forename: Björn
authors.initials: B
authors.lastname: Drobe
authors.forename: Yuwen
authors.initials: Y
authors.lastname: Wang
authors.forename: Ke
authors.initials: K
authors.lastname: Chen
authors.forename: Eu Jin
authors.initials: EJ
authors.lastname: Seow
authors.forename: Fan
authors.initials: F
authors.lastname: Lu
mesh_terms: D000293:Adolescent; D044466:Asian People; D002648:Child; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011932:Reading; D013647:Task Performance and Analysis; D018910:Video Games