A Comparative Study of the Neuro-Ophtha (NO) Lollipop and Hertel Exophthalmometers in Measuring Anterior-Posterior Globe Position among Patients without Orbital Disease

Objective: To compare the Neuro-Ophtha (NO) Lollipop against the Hertel exophthalmometer, which is as gold standard, in measuring anterior-posterior (A-P) globe position among patients without orbital disease.

Methods: 423 patients without history of orbital problems, aged 18 years old and above were recruited. Measurements of A-P position of globe were done using Hertel (Ophthalmologist A) and NO Lollipop (Ophthalmologist B) independently on the same patient, in two separate rooms and the same day.

Results: Results showed the A-P globe position measurements were significantly higher using the NO Lollipop as compared to Hertel exophthalmometer. After log transformation of data, a mean difference in the A-P globe position of 0.04977 (log10) or 1.12mm (95% CI 0.12mm to 2.12mm) between Hertel and NO Lollipop readings on the right eye (OD) and 0.04652 (log10) or 1.11mm (95% CI 0.11mm to 2.11mm) on the left eye (OS) were obtained. Significant difference in the mean A-P position readings between Hertel and NO Lollipop exophthalmometer were seen in this study on OD (t=25.2, p=0.000) and OS (t=22.5, p=0.00).

Conclusion: In patients without orbital disease, NO Lollipop overestimates the anterior-posterior globe position by as much as 1.11-1.12 mm compared to Hertel exophthalmometer.  In clinical setting, NO Lollipop may be used as an alternative instrument when Hertel exophthalmometer is not available.