A Comparative Analysis of Monocular Excursion Measures

Purpose: The range of monocular excursions can be determined by several different methods, including the Aimark Perimeter, Synoptophore and Modified Goldman Perimeter. However the relationship between these tests is poorly understood. Methods: This is a prospective, cross-sectional study to compare the extent of monocular excursions by three methods. For each eye, the Goldman and the Synoptophore measured 8 axes, and the Aimark measured 12. Each assessment was timed. The results for direct elevation of the right eye are analyzed and comparisons made by the Bland-Altman analysis. Results: One hundred and fourteen patients were recruited: 64 with abnormal eye movements and 50 with no ocular motility restrictions. The mean +/- SD rotations in degrees were Aimark 50.6 +/- 12.4, Synoptophore 24.6 +/- 5.78, and Goldman 40.6 +/- 9.14. The Bland-Altman plots showed the mean bias was highest when comparing the Synoptophore to the Aimark (-26 +/- 11.71) where the bias was inversely proportional to the rotation. The mean +/- SD times per axes in seconds were Aimark 16.38 +/- 4.62, Synoptophore 20.98 +/- 57.23, and Goldman 16.16 +/- 9.76. There was no significant difference in time taken between the tests (ANOVA, p = 0.50). Conclusion: There is considerable variation between these three methods for measurement of monocular excursions, but the difference in the time taken is accounted for by the variation in the number of axes assessed.