Ocular Torsion in an Upright Position in Normal Subjects.

There are few methods of studying otolith function clinically. Ocular torsion, deviation of the eye in the roll plane in an upright position, is considered to reflect otolith function, especially that of the utricle. We measured ocular torsion by laser fundus photograph in 53 normal subjects. In the case of the right eye, counterclockwise rotation of the eye from the perspective of the examiner was defined as positive excyclotropia, while clockwise rotation was defined as positive in the left eye. The mean value was 7.7° (range; -0.2°-15.5°) in the left eye and 7.5° (range; 0°-15.8°) in the right eye. The mean difference in the values for both eyes was 3.3° (range; 0°-10.0°). Test·retest variability was found to be within 4° in the left eye, in the right eye and in the difference in values for both eyes. As a result, we concluded that a value beyond this range can be considered pathological. Research on otolith function in various peripheral vestibular diseases will be facilitated by these date.