Vertical Rectus Muscle Overaction after Local Anesthesia

Han, S K; Hwang, J M

Abstract

To determine causative factors of vertical rectus overaction after local anesthesia, prism and cover test in the diagnostic positions of gaze and forced duction testing were performed in six patients with vertical rectus overaction after local anesthesia. Tensilon test, thyroid function test, and/or orbit CT were done in possible patients. Five patients showed ipsilateral hypertropia with superior rectus overaction and one patient, ipsilateral hypotropia with inferior rectus overaction. The deviation was greater in the field of action of the presumed tight muscle in all patients. In one patient, partial fibrosis of superior rectus presumably caused by a bridle suture was found. In two patients, inferior rectus of the contralateral eye was restrictive. Four patients had past histories of systemic dysthyroidism, abnormal findings in thyroid function test, and/or orbit CT findings compatible with thyroid ophthalmopathy. Thyroid disease may be more commonly associated with vertical rectus overaction developed after local anesthesia than previously reported. A bridle suture was found to be able to cause rectus muscle fibrosis. In these patients, retrobulbar anesthesia, bridle suture and thyroid ophthalmopathy were thought to be the causative factors of vertical rectus overaction after local anesthesia.