Objective: The aim of this study was to assess the agreement between four different methods of measuring interpupillary distance.
Methods: This cross-sectional study evaluated IPD in healthy adults using four methods, including corneal reflex and limbus-based manual methods, autorefractometer and mobile application (Warby Parker). Data analysis was conducted in SPSS version 27, and intraclass correlation coefficient and Bland-Altman plots were employed to assess the agreement between these methods.
Results: A total of 90 individuals with a mean age of 34.58±8.86 years participated in this study. There was no significant relationship between age and IPD (P>0.132). The ICC indicated good statistical agreement between the methods (ICC=0.918, 95% CI:0.845-0.953). Also, Bland-Altman analysis showed that the 95% limits of agreement were not wide in most comparisons and were clinically acceptable. The highest difference was observed between the limbus-based manual method and the mobile application (mean difference: 0.67±1.30 mm, 95% LoA: -3.23 to 1.89 mm), and the lowest difference occurred between the autorefractometer and the manual corneal reflex method (mean difference: -0.05±0.84 mm, 95% LoA: -1.70 to 1.60 mm).
Conclusion: According to the results, the lowest difference in measuring IPD that was statistically and clinically significant was noted between the autorefractometer and the manual corneal reflex method and the highest difference was found between the limbus-based method and the mobile application. It is recommended to use standard methods for achieving accurate measurements and the results obtained from mobile applications should not be the only basis for clinical decision-making.