Overview of Graves' Ophthalmopathy
Graves' ophthalmopathy (GO) is a condition that primarily affects the extraocular muscles, the muscles that rotate the eyeball up, down, and to the sides. It is closely associated with Graves' disease, an autoimmune disorder that causes the thyroid to produce excess thyroid hormone (hyperthyroidism). Graves' ophthalmopathy is also known as thyroid eye disease or thyroid-associated ophthalmopathy.
In GO, an unknown antigen (substance that triggers an immune response) activates lymphocytes (a type of white blood cell), which infiltrate extraocular muscle tissue and other orbital tissues, producing inflammation and causing the tissues to swell. The swollen eye muscles force the eyeball to bulge out of the bony orbit (i.e., eye socket).
Graves' ophthalmopathy and Graves' disease are two separate conditions that run independent courses. GO may occur long before, at the same time as, or long after thyroid disease is diagnosed and treated. Although most patients with Graves' disease have Graves' ophthalmopathy, about 10% of patients with GO have normal thyroid function.
Progression of the disease usually stops on its own within a 2-year period and it rarely recurs. Mild symptoms may completely self-resolve, but treatment may be necessary to restore eyelid function, improve appearance, and correct vision.
Incidence and Prevalence Graves' disease occurs in less than 1/4 of 1% of the U.S. population. About 3,000,000 patients in the United States and Europe have the condition and there are 37,000 new cases per year in the United States. Up to 80% of patients with Graves' disease develop eye symptoms. Graves' ophthalmopathy is more prevalent in Caucasian women between the ages of 30 and 50.
Smokers are more likely than nonsmokers to develop Graves' disease and GO and are more likely to develop more severe symptoms of eye disease.
Symptoms of GO vary. Redness and irritation in the eyes is common, but inflammation that causes permanent or serious vision damage occurs in less than 1% of cases.
Other ocular symptoms include:
- Double vision
- Eye dryness
- Eye muscle weakness
- Excessive tearing
- Exophthalmos proptosis (protrusion of the eyes)
- Increased intraocular pressure
- Light sensitivity
- Swelling of the eyelids
- Upper and lower eyelid retraction
Patients may have difficulty closing their eyes completely, which can lead to irritation, dryness, and corneal abrasions. Vision is affected in severe cases.
Eye muscle swelling can increase pressure within the eye as well as compress the optic nerve. Because of the increased pressure, GO patients carry a risk for glaucoma.
The eye muscles may become impaired to the point where they are unable to freely move the eye in all directions, leading to double vision (diplopia). In rare instances, swelling may compress the optic nerve in one or both eyes, leading to optic neuropathy and possibly vision loss.