Appearance of Graves' disease on orbital computed tomography

Extraocular muscle enlargement was symmetrical in 70% and asymmetrical in 30% of patients with Graves' ophthalmopathy. True unilateral muscle involvement occurred in 6%. Computed tomography (CT) showed bilateral orbital involvement in 50% of patients presenting clinically with unilateral eye signs. In patients without a clinically apparent ophthalmopathy, CT demonstrated muscle enlargement in 40%. The medial and inferior rectus muscles were the most frequently and most severely involved. Orbital radiation therapy can result in a decrease in size of involved muscles.