title: Changes in the interpupillary distance with age and its effect on the near fusion free position.
abstract: OBJECTIVE
  The effect of the rate of the interpupillary distance (IPD) change with age on the near fusion free position was investigated in the present study.
  
  
  METHODS
  Three hundred and fifty-two children aged from 2 to 16 years of age were tested. Interpupillary distance was estimated with a modified Viktorin's method and the near fusion free position was measured with a modified Maddox Wing.
  
  
  RESULTS
  The results reveal a significant difference in IPD growth rate between females and males and between children aged below and above 5 years. Most children below 5 years of age were orthophoric, but heterophoria became more common above 5 years of age.
  
  
  CONCLUSIONS
  The present study suggests that the oculomotor control system for convergence can compensate for age changes in IPD.
authors.affiliation: School of Optometry, University of New South Wales, Sydney, Australia.
authors.forename: A H
authors.initials: AH
authors.lastname: Chen
authors.forename: D J
authors.initials: DJ
authors.lastname: O'Leary
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D000886:Anthropometry / Q000379:methods; D002648:Child; D002675:Child, Preschool; D004948:Esotropia / Q000503:physiopathology; D005260:Female; D006801:Humans; D007498:Iris / Q000033:anatomy & histology; D008297:Male; D011680:Pupil / Q000502:physiology*