title: Gain and movement time of convergence-accommodation in preschool children.
abstract: BACKGROUND
  Convergence-accommodation is the synkinetic change in accommodation driven by vergence. A few studies have investigated the static and dynamic properties of this cross-link in adults but little is known about convergence-accommodation in children. The purpose of this study was to develop a technique for measuring convergence-accommodation and to study its dynamics (gain and movement time) in a sample of pre-school children.
  
  
  METHODS
  Convergence-accommodation measures were examined on thiry-seven normal pre-school children (mean age = 4.0 +/- 1.31 yrs). Stimulus CA/C (sCA/C) ratios and movement time measures of convergence-accommodation were assessed using a photorefractor while subjects viewed a DOG target. Repeated measures were obtained on eight normal adults (mean age = 23 +/- 0.2 yrs).
  
  
  RESULTS
  The mean sCA/C ratios and movement times were not significantly different between adults and children (0.10 D/Delta [0.61 D/M.A.], 743 +/- 70 ms and 0.11 D/Delta [0.50 D/M.A.], 787 +/- 216 ms). Repeated measures on adults showed a non-significant mean difference of 0.001 D/Delta.
  
  
  CONCLUSIONS
  The results suggest that the possible differences in crystalline lens (plant) characteristics between children and adults do not appear to influence convergence-accommodation gain or duration.
authors.affiliation: School of Optometry, University of Waterloo, Waterloo, Ontario, Canada. rsuryaku@uwaterloo.ca
authors.forename: R
authors.initials: R
authors.lastname: Suryakumar
authors.forename: W R
authors.initials: WR
authors.lastname: Bobier
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D000375:Aging / Q000502:physiology; D002675:Child, Preschool; D003290:Convergence, Ocular / Q000502:physiology*; D006801:Humans; D010775:Photic Stimulation / Q000379:methods; D015203:Reproducibility of Results; D013997:Time Factors