Four recti enlargement at orbital apex and thyroid associated optic neuropathy

Objective: To determine the site of muscle enlargement in thyroid-associated ophthalmopathy and optic neuropathy in Ramathibodi Hospital. Material and Method: Data and images of MRI and CT of patients with thyroid-associated ophthalmopathy were retrospectively reviewed. Neuro-ophthalmologic data and correlation to the imaging findings were analyzed. Results: Among 19 patients with thyroid-associated ophthalmopathy, 20 imaging studies were collected. There were 4 patients with bilateral disease and crowdedness of 4 recti muscle. All of them had thyroid associated optic neuropathy. One out of 19 patients underwent two different sessions study. During her first study, right optic nerve was involved with the crowding of right optic nerve but 7 months later her left optic nerve became involved with crowding of the left optic nerve and the right 4 recti appeared smaller. Conclusion: Four recti muscle enlargement in thyroid-associated ophthalmopathy, like four-leaf clover in coronal section of imaging study, may be an important sign of thyroid associated optic neuropathy.