title: Nearwork-induced transient myopia in preadolescent Hong Kong Chinese.
abstract: OBJECTIVE
  To compare the magnitude and time course of nearwork-induced transient myopia (NITM) in preadolescent Hong Kong Chinese myopes and emmetropes.
  
  
  METHODS
  Forty-five Hong Kong Chinese children, 35 myopes and 10 emmetropes aged 6 to 12 years (median, 7.5), monocularly viewed a letter target through a Badal lens for 5 minutes at either 5.00- or 2.50-D accommodative demand, followed by 3 minutes of viewing the equivalent target at optical infinity. Accommodative responses were measured continuously with a modified, infrared, objective open-field autorefractor. Accommodative responses were also measured for a countercondition: viewing of a letter target for 5 minutes at optical infinity, followed by 3 minutes of viewing the target at a 5.00-D accommodative demand. The results were compared with tonic accommodation and both subject and family history of refractive error.
  
  
  RESULTS
  Retinal-blur-driven NITM was significantly greater in Hong Kong Chinese children with myopic vision than in the emmetropes after both near tasks, but showed no significant dose effect. The NITM was still evident 3 minutes after viewing the 5.00-D near task for 5 minutes. The magnitude of NITM correlated with the accommodative drift after viewing a distant target for more than 4 minutes, but was unrelated to the subjects' or family history of refractive error.
  
  
  CONCLUSIONS
  In a preadolescent ethnic population with known predisposition to myopia, there is a significant posttask blur-driven accommodative NITM, which is sustained for longer than has previously been found in white adults.
authors.affiliation: Neurosciences Research Institute, School of Life and Health Sciences, Aston University, Birmingham, United Kingdom. j.s.w.wolffsohn@aston.ac.uk
authors.forename: James Stuart
authors.initials: JS
authors.lastname: Wolffsohn
authors.forename: Bernard
authors.initials: B
authors.lastname: Gilmartin
authors.forename: Roger Wing-hong
authors.initials: RW
authors.lastname: Li
authors.forename: Marion Hastings
authors.initials: MH
authors.lastname: Edwards
authors.forename: Sandy Wing-shan
authors.initials: SW
authors.lastname: Chat
authors.forename: John Kwok-fai
authors.initials: JK
authors.lastname: Lew
authors.forename: Bibianna Sin-ying
authors.initials: BS
authors.lastname: Yu
mesh_terms: D000065:Accommodation, Ocular; D044466:Asian People; D002648:Child; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D009216:Myopia / Q000208:ethnology* / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors; D014937:Work