The Case of Inferior Oblique Muscle Overaction after Orbital Trauma

ABSTRACT

PURPOSE: To report a case of inferior oblique muscle overaction after orbital trauma. CASE SUMMARY: A 19-year-old male presented with a blowout fracture of the right inferior orbital wall. The patient had no history of facial asymmetry, head tilt, strabismus or diplopia. The day after the reduction operation, the patient complained of diplopia on the down-gaze. The patient had orhthophoria in the primary position. However, the right eye showed a limitation on infraduction. Six weeks later, the limitation of infraduction resolved, however the diplopia worsened. The right eye showed excessive elevation in adduction and hypertropia in the primary position. The hypertropia increased on left gaze, and decreased on right gaze. Bielschowsky's head test revealed a negative result. The fundus photographs showed a mild excyclotorsion of the right eye. Five months later, the symptoms and signs were stable and surgery was performed. Under general anesthesia, the exaggerated forced duction test and traction with strabismus hook on the right inferior oblique muscle revealed tightness. The inferior oblique muscle was found to be recessed. After the operation, the diplopia, hypertropia and the excessive elevation on adduction of the right eye resolved. CONCLUSIONS: A contracture and resultant overaction of inferior oblique muscle could develop after trauma on the inferior orbital wall. Trauma on the inferior orbital wall should be considered as one of the primary causes of acquired inferior oblique overaction.