Purpose: This study introduces a novel exophthalmometry method utilizing a mobile platform to obtain calibrated quantitative measurements of globe position and compares its reliability to Hertel exophthalmometry.
Methods: A prospective, comparative study included 50 patients (99 eyes) for a total of 594 mobile measurements. Healthy individuals from the community in Augusta, Georgia, and individuals from a routine oculoplastics clinic at Mayo Clinic in Rochester, Minnesota, were included to represent variety within the population. The main outcome was the inter-modality correlation and agreement between Hertel and mobile exophthalmometry, and the intra-observer and inter-observer reliability with repeated mobile measurements.
Results: There was no significant difference in the measurements obtained by Hertel exophthalmometry and mobile exophthalmometry. There was a strong linear correlation between Hertel and mobile exophthalmometry with a Pearson Correlation Coefficient of 0.910 and 0.888 for the right and left eyes, respectively (p < .001, 2-tailed). Bland-Altman plot analysis showed excellent agreement between the two modalities. The mobile platform demonstrated high intra-observer reliability with a Cronbach's alpha of 0.992 and 0.985 for the right and left eyes. An intraclass correlation coefficient of 0.992 (95% CI: 0.987-0.995) for the right eye and 0.986 (95% CI: 0.978-0.991) for the left eye demonstrated excellent reliability between observers.
Conclusions: Mobile exophthalmometry may be a promising tool for obtaining calibrated quantitative measurements of globe position for situations in which Hertel exophthalmometry is not available. The strong correlation and excellent agreement between Hertel and mobile measurement suggest that mobile exophthalmometry can yield reliable and accurate measurements.
Keywords: Exophthalmometry; Hertel exophthalmometry; mobile measurements.