Thyroid-associated ophthalmopathy is a self-limiting autoimmune disease associated mainly with Graves' disease, but also with Hashimoto's thyroiditis (HT) and euthyroid states. There are two distinct stages of the disease, an active inflammatory stage followed by inactive quiescent stage. Eye disease activity/severity is independent of gender, age, thyroid function, or smoking. There are no effective means of preventing the disease or reliably altering its course. Current therapeutic options include local supportive measures, corticosteroids, external beam radiation and steroid-sparing immunosuppressive agents for reducing the inflammation during active disease and surgery for correcting the residual abnormalities secondary to fibrosis in the inactive state of the disease. This chapter explores Hashimoto's ophthalmopathy.
TopIntroduction
Autoimmune thyroid diseases comprise two main clinical presentations: Graves’ disease (hyperthyroidism) and Hashimoto’s thyroiditis (HT) (hypothyroidism), both characterized by antibodies that attack the thyroid. Indeed, these disorders are the opposite ends of the same underlying cause. Thyroid eye disease, also known as thyroid-associated ophthalmopathy or orbitopathy (TAO), is an autoimmune disorder of the extra-ocular muscles and surrounding orbital connective tissue. It is usually associated with Graves' disease, affecting approximately 25% of these patients, but can also be associated with HT occurring in nearly 6% of those patients (Boulos, 2004; Yamada, 2000; Maheshwari, 2012; Dagi, 2010; El-Kaissi, 2004).
The close clinical relationship between hyper-thyroidism (Graves' disease), Graves' ophthalmopathy, and thyroid dermopathy (peritibial myxedema) suggests that these conditions arise from a single underlying systemic process with variable expression in the thyroid gland, eyes, and skin.
Bilateral ocular disease and hyperthyroidism usually occur simultaneously or within 18 months of each other, although occasionally Graves' ophthalmopathy precedes or follows the onset of hyperthyroidism by many years (Wiersinga, Smit, van der Gaag, & Koornneef, 1988). Approximately, 50% of patients with Graves' hyper-thyroidism have symptoms of Graves' ophthalmopathy. Thes include a dry and gritty ocular sensation, photophobia, excessive tearing, double vision, and a pressure sensation behind the eyes. The most common Typical signs include upper eyelid retraction, periorbital oedema, proptosis, and Typical clinical signs include upper eyelid retraction, periorbital edema and erythema, proptosis (Figure 1), and impairment of eye motility (Bahn, 2010). Approximately 3%-5% of patients with Graves’ ophthalmopathy have severe disease with intense pain, inflammation, and sight-threatening corneal ulceration or compressive optic neuropathy (Wiersinga, & Bartalena, 2002). Subclinical eye involvement is common as revealed by magnetic resonance imaging (MRI) or computed tomographic (CT) scanning that show extraocular-muscle enlargement (Enzmann, Donaldson, & Kriss, 1979), in approximately 70% of adult patients with Graves’ hyperthyroidism. Although clinically unilateral Graves’ ophthalmopathy is not common, orbital imaging generally confirms the presence of asymmetric bilateral disease (Wiersinga, Smit, van der Gaag, Mourits, & Koornneef 1989).
Figure 1. A lady with thyroid associated ophthalmopathy showing proptosis, periorbital edema, chemosis, and conjunctivitis
Thyroid Dermopathy (nodular or diffuse thickening of pretibial skin) sometimes progresses to a debilitating disease. Although diagnosed on physical examination in only 13% of patients with severe Graves’ ophthalmopathy, subclinical involvement of the skin of the legs and other regions of the body occurs more commonly (Fatourechi, 2005). Approximately 20% of patients with thyroid dermopathy have thyroid acropachy, manifesting as clubbing of fingers and toes.