Thyroid eye disease is a specific disorder that may develop in patients with Graves’ disease. It is characterized by inflammation and swelling of the tissues that surround the eyeballs. Other terms used to identify this disorder include Graves’ ophthalmopathy and dysthyroid exophthalmopathy.
While the underlying cause of thyroid eye disease is not completely understood, it has been suggested that it may represent an autoimmune disorder. There is some evidence that thyroid stimulating immunoglobulins that are produced in the setting of Graves’ disease may bind to structures in the tissues that surround the eyeballs. If this binding occurs, it may draw specific types of white blood cells called T cells and macrophages into these tissues. These T cells and macrophages may release chemical compounds called cytokines that promote inflammation. Cytokines may also promote the growth and division of cells called fibroblasts that are distributed within the tissues that surround the eyeballs. As these fibroblasts grow and divide, they may produce and secrete chemical compounds called glycosaminoglycans. Glycosaminoglycans secreted by fibroblasts may absorb a significant amount of water, contributing to the swelling of tissues.
Thyroid eye disease is fairly common among patients diagnosed with Graves’ disease. When sensitive tests are used to check for evidence of thyroid eye disease, up to 70% of all patients diagnosed with Graves’ disease may be noted to have some extraocular muscle swelling. Most patients with thyroid eye disease present with findings that are usually limited to mild inflammation and swelling of the eyelids. Only about 5% of patients with Graves’ disease develop thyroid eye disease that is severe enough to require medical attention. On the whole, thyroid eye disease is more common among women, though men who present with thyroid eye disease are more likely to require treatment. Thyroid eye disease tends to be more common among patients who smoke. In rare cases, patients diagnosed with Graves’ disease may develop isolated thyroid eye disease without any evidence of thyrotoxicosis or hyperthyroidism. This disorder is called euthyroid Graves’ disease or euthyroid ophthalmopathy.