Quantitative measurement of the angle of ocular movements

Abstract

Purpose: To measure the maximum angle of ocular movements using photographs of the cardinal positions. Methods: One hundred four orthotropic subjects and fifty patients with intermittent exotropia were enrolled in this study. Photographs were obtained in the 9 cardinal positions of gaze and the images were processed using Photoshop. The images were analyzed using the Image J program to measure the angle of version. The maximum angle of the 9 cardinal positions was quantified using a modified limbus test. Results: The mean angles of maximum version in orthotropic subjects were adduction 47.4°, abduction 46.4°, elevation 31.8°, depression 47.8°, elevation in adduction 39.7°, elevation in abduction 40.7°, depression in adduction 52.7°, and depression in abduction 49.2°. The mean angle of maximum elevation was significantly smaller than that of depression (P<0.001). In patients with intermittent exotropia, the angle of adduction was smaller than that of abduction (adduction 38.8° vs. abduction 45.2°; P = 0.009). The angle of maximum version for males was significantly greater than that for females, except for inferior gaze. Conclusions: A modified limbus test using photographs of the 9 cardinal positions is an objective and reproducible tool for quantifying ocular movement. Considering its simplicity, ease of use, and low cost, it has clear applications in clinical practice.