CHANGES IN THE INTERPUPILLARY DISTANCE WITH AGE AND ITS EFFECT ON THENEAR FUSION FREE POSITION

Purpose: The effect of the rate of the interpupillary distance (IPD) c hange with age on the near fusion free position was investigated in th e present study.Methods: Three hundred and fifty-two children aged fro m 2 to 16 years of age were tested. Interpupillary distance was estima ted with a modified Viktorin's method and the near Fusion Free positio n was measured with a modified Maddox Wing. Results: The results revea l a significant difference in IPD growth rate between females and male s and between children aged below and above 5 years, Most children bel ow 5 years of age were orthophoric, but heterophoria became more commo n above 5 years of age. Conclusion: The present study suggests that th e oculomotor control system for convergence can compensate for age cha nges in IPD.