title: The effect of a beta-adrenoceptor antagonist on accommodative adaptation in Hong Kong children.
abstract: OBJECTIVE
  Increased susceptibility to nearwork-induced accommodative adaptation has been suggested as a risk factor for myopia development. We investigated whether accommodative adaptation may explain in part the high prevalence of myopia in Hong Kong children and examined the effect of beta-antagonism with topical timolol maleate on accommodative adaptation.
  
  
  METHODS
  Thirty children (10 emmetropes and 20 myopes) aged between 8 and 12 years were recruited. Tonic accommodation was measured before and after 5 min of video game-playing using an open-field Shin-Nippon autorefractor. Measurements were repeated 30 min after timolol instillation.
  
  
  RESULTS
  Children with progressing myopia demonstrated accommodative adaptation following the near task, whereas stable myopes showed counter-adaptive, hyperopic accommodative changes. Timolol increased the magnitude of accommodative adaptation in the stable myopes but had little effect on responses of the progressing myopes or emmetropes.
  
  
  CONCLUSIONS
  Neuropharmacological modulation of the accommodative system may have a possible etiological role in the progression of myopia.
authors.affiliation: Centre for Health Research, School of Optometry, Queensland University of Technology, Brisbane, Australia. jc.chen@qut.edu.au
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Chen
authors.forename: Katrina L
authors.initials: KL
authors.lastname: Schmid
authors.forename: Brian
authors.initials: B
authors.lastname: Brown
authors.forename: Marion H
authors.initials: MH
authors.lastname: Edwards
mesh_terms: D000065:Accommodation, Ocular / Q000187:drug effects*; D000221:Adaptation, Ocular / Q000187:drug effects*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D002648:Child; D005260:Female; D006723:Hong Kong / Q000208:ethnology; D006801:Humans; D008297:Male; D009216:Myopia / Q000208:ethnology / Q000503:physiopathology; D013999:Timolol / Q000494:pharmacology*
chemical_list: D000319:Adrenergic beta-Antagonists; D013999:Timolol