PURPOSE: To evaluate the effect of individual differences in IPD (interpupillary distance) on convergence and divergence amplitudes measured at near and at distant fixation targets.
METHODS: Ninety-three healthy subjects were enrolled. Group 1 included subjects with smaller than normal IPD (27 subjects), Group 2 included those with larger than normal IPD (31 subjects) and Group 3 included those with normal IPD (35 subjects). Outcome measures were best corrected visual acuity (BCVA), binocular vision level (TNO test), convergence and divergence amplitudes at near and at distance.
RESULTS: There was no statistically significant difference between Group 1, 2 and 3 regarding age or clinical characteristics. The differences in gender distribution between Groups 2 and 3 and between Groups 1 and 2 were significant (chi square test, p=0.001 for both). There was no statistically significant difference between the groups in the values of NCA (near convergence amplitude), NDA (near divergence amplitude), and DCA (distant convergence amplitude). There was a statistically significant difference between in mean DDA (distant divergence amplitude) between Groups 2 and 3 (p=0.01).
CONCLUSION: Differences in IPD can affect an individual’s vergence amplitudes and binocular vision level.