Assessing agreement of inter-pupillary distance measurements between contact and non-contact digital pupillometers during COVID-19

Purpose: Interpupillary distance (IPD) measurement is important in various sub-fields in ophthalmology and vision sciences. Social distancing is one of the protocols which is being followed since COVID -19 pandemic across the globe. This protocol was a major limitation while measuring the IPD during spectacle dispensing. Hence, we need an alternate method which allows to measure IPD at 1-meter distance. This study aims to report the agreement between contact and non-contact IPD measurements. Methods: Monocular and binocular distance and near IPD were measured using contact (Essilor pupillometer; Pupillon, Essilor, France) and non-contact (OptikamPad; Optikam Tech Inc., Canada) measuring device. Gender effects were assessed using Wilcoxon and Mann-Whitney tests respectively. Agreement was assessed using Spearman correlation and Bland-Altman plots. Results: A total of fifty subjects IPD data were analysed (male 62.0%). The mean age ± standard deviation (SD) for the study subjects were 53.35 ± 11.91 (range 32 - 81) years. The IPD measurements by Contact digital pupillometer and Non-Contact digital IPD measuring devices showed an insignificant difference both for monocular and binocular IPDs and also had a good agreement between the methods. Conclusions: The IPD measurements by the Non-Contact digital IPD measuring device was comparable with the Contact digital pupillometer. In order to maintain social distance during COVID 19, the non-contact digital measuring device can be considered as an alternate tool for IPD measurement.