Thyroid ophthalmopathy is an autoimmune orbital disorder closely associated with Graves' disease, although both conditions may also occur isolatedly. Thyroid ophthalmopathy may precede, coincide or follow the thyroid dysfunction onset and may rarely occur in euthyroid and hypothyroid patients. The extraocular muscles are most frequently involved and become enlarged resulting in ophthalmoplegia and proptosis. Other relevant signs include palpebral retraction, conjuctival hyperemia and periorbitary edema. Visual loss may occur in association with compressive optic neuropathy at the orbital apex. Thyroid ophthalmopathy is characterized by inflammation, congestion, hypertrophy and fibrosis involving fat and the orbital muscles. The disease activity is divided into two phases: an acute or inflammatory phase and a second one corresponding to an inactive phase associated with fibrotic changes and fat infiltration of the retrobulbar tissues. The diagnosis is based on clinical findings and imaging methods are indicated in case of doubt or suspicion of optic neuropathy. Computed tomography and magnetic resonance imaging can confirm the diagnosis, allowing the evaluation of the critical region of the orbital apex. Magnetic resonance imaging is the method of choice considering the superior tissue contrast resolution, besides the capacity of evaluating the disease activity by means of long TR sequences and detecting inflammatory changes, with a relevant role in a timely therapeutic planning, which may improve the prognosis.
Thyroid ophthalmopathy; Extraocular muscles; Magnetic resonance imaging; Computed tomography
