Intermittent Exotropia Associated with Simulated Superior Oblique Palsy

ABSTRACT

PURPOSE: To obtain guideline of diagnosis and treatment when hyperdeviation associated with intermittent exotropia shows symptoms similar to superior oblique palsy (SOP). METHODS: We reviewed the charts retrospectively in 27 patients showing simulated SOP in intermittent exotropia, in which hyperdeviation in primary gaze and 10PD or more by Bielschowsky head tilt test were present. Overaction of Inferior oblique, (IOOA) dysfunction of superior oblique, and forveal extorsion more than +2 were excluded including reoperation and head tilt history. All patients were undergone horizontal muscle surgery only. The postoperative changes of deviation were analyzed at postoperative one day, one month, six month, and one year. RESULTS: Average amount of distant horizontal deviation in primary gaze was 32.3+/-9.58PD. Hyperdeviation was 3.8+/-2.52PD. Degree of IOOA averaged +1.18 in hypertropic eye, and +1.06 in hypotropic eye. Only 10 patients (37%) had foveal extorsion less than +2 in degree. Average vertical deviation of hypertropic eye side was 12.7+/-2.93PD on head tilt test. After horizontal surgery only, the amount of hyperdeviation decreased to 1.3PD at 1st day. On head tilt test, hyperdeviation was almost eliminated showing 0.6PD on the hypertropic side and 0.1PD on the contralateral eye at one month. All patients were aligned up to the follow-up of one year. CONCLUSIONS: To differentiate simulated SOP from intermittent exotropia with hyperdeviation, none of head tilt history, mild foveal extorsion, mild oblique dysfunction less than +3, double Maddox rod test, and forced duction test are important guidelines. Horizontal muscle surgery is only needed to remove exodeviation and hyperdeviation.