Extraocular Muscle Palsy in Patients with Chronic Orbital Myositis.

BACKGROUND Orbital myositis (OM) is a subgroup of idiopathic orbital inflammation. It can involve single or multiple extraocular muscles and result in restriction or paresis of extraocular muscles. METHOD We reported two unusual cases of extraocular muscle paresis in the fibrotic stage of chronic OM and reviewed the literature related to this finding. RESULTS The first case was of a 38-year-old woman with chronic OM with large-angle right eye exotropia and right medial rectus paresis. She received a botulinum A toxin injection into the right lateral rectus muscle as a first treatment, but it was unsuccessful in correcting her deviation. Subsequently, she underwent two strabismus surgeries, which successfully resolved her diplopia in primary gaze. The second case was of a 35-year-old woman with chronic OM and left lateral rectus palsy, which was managed with a botulinum A toxin injection. CONCLUSION OM can cause extraocular muscle palsy in the chronic fibrotic stage of the disease.