Changes in the interpupillary distance (IPD) with ages and its effect on the near convergence/distance (NC/D) ratio

This study aims at determining the mean value of the ophthalmic anthropometrics parametar-IPD (Interpupillary distance) and the mean value of NC/D (Near convergence/distance) in 300 subjects aged 5 to 60 years. The influence of IPD on the NC/D ratio in the same subjects will also be investigated. The investigation showed that the mean value of IPD is 60.5 +/- 2.4 cm, and the mean value of NC/D ratio is 4.95 +/- 2.28 prD. Mean IPD of 5.1 cm in 5-year old children increases to 6.3 cm in adult over 20. In adulthood, IPD remains the same, i.e. 6.3 cm. Our study showed that the NC/D ratio is stable during lifetime. Since NC/D is stabile and IPD changes during lifetime, it is evident that factors other than IPD, such as convergence and accommodation, influence the stability of the NC/D ratio.