Evaluation of agreement among four different methods for measuring inter-pupillary distance in healthy adults

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 ۲۷, and intraclass correlation coefficient and Bland-Altman plots were employed to assess the agreement between these methods.Results: A total of ۹۰ individuals with a mean age of ۳۴.۵۸±۸.۸۶ years participated in this study. There was no significant relationship between age and IPD (P>۰.۱۳۲). The ICC indicated good statistical agreement between the methods (ICC=۰.۹۱۸, ۹۵% CI:۰.۸۴۵-۰.۹۵۳). Also, Bland-Altman analysis showed that the ۹۵% 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: ۰.۶۷±۱.۳۰ mm, ۹۵% LoA: -۳.۲۳ to ۱.۸۹ mm), and the lowest difference occurred between the autorefractometer and the manual corneal reflex method (mean difference: -۰.۰۵±۰.۸۴ mm, ۹۵% LoA: -۱.۷۰ to ۱.۶۰ 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.

Keywords:

Interpupillary distance , autorefractometer , Mobile application