The thyroid gland is a small, butterfly-shaped gland in the neck. It's responsible for production of two hormones that control metabolism: thyroxine (T4) and triiodothyronine (T3).

The body must keep an even production of thyroid hormones to function well. Underproduction of thyroid hormones, called hypothyroidism, can lead to fatigue, weight gain, depression, feeling cold, dry skin and hair, mood swings, hoarse voice, constipation and, in women, heavy menstrual flow. Overproduction of thyroid hormones, or hyperthyroidism, can cause weight loss, nervousness, anxiety, irritability, tremors, sleeping problems, muscle weakness, intolerance to heat and, in some cases, enlargement of the thyroid.

The American Association of Clinical Endocrinologists estimates 27 million Americans have thyroid disease. More than 80 percent of them are women.

Graves' Disease

Graves' Disease is a condition caused by overproduction of the thyroid hormone, thyroxine. According to the National Graves' Disease Foundation, it's the leading cause of hyperthyroidism. It affects women eight times more often than men and typically occurs between 20 and 50.

Graves' disease occurs when the immune system mistakenly attacks the thyroid gland. That causes production of an antibody (thyrotropin receptor antibody) which stimulates the thyroid to make too much thyroxine.

Thyroid Eye Conditions

Thyroid orbitopathy is a specific condition associated with an immune attack on the thyroid gland. It can occur in patients with Graves' disease or other autoimmune-related conditions, like rheumatoid arthritis, Crohn's disease and Paget's disease. Researchers estimate about 40 to 60 percent of patients with hyperthyroidism will develop some degree of thyroid orbitopathy.

In thyroid orbitopathy, the tissues behind the eye swell, pushing the eye forward and out of its natural socket. The eyes appear to be bulging and the eyelids may not close completely. Patients may complain of dry, itchy or irritated eyes. The condition can also cause double or blurred vision, mild eye pain and sensitivity to light. In severe cases thyroid orbitopathy can lead to ulceration of the cornea or compression of the optic nerve.

For most patients, thyroid orbitopathy is mild and progresses slowly before gradually resolving on its own. Significant symptoms develop in 10 to 15 percent of patients. Women are four times more likely to develop the condition than men. Smokers appear to have a much greater risk for severe symptoms.

Treating Thyroid Eye Disease

If symptoms of thyroid orbitopathy become severe, or patients are seriously concerned about the cosmetic appearance of their bulging eyes, some physicians will perform a surgical correction. Plastic Surgeon Allan Wulc, M.D., uses a procedure called orbital decompression. Instruments are passed through the nose to reach the eye socket from behind. A few sinus cavities are removed. Then, the bone behind the eye socket is removed. If necessary, a small incision is made into the bone on the outer side of the eye socket and the surrounding bone is thinned. Through other incisions, a small amount of fat from the upper and lower eyelids may be removed. The procedure enlarges the space behind the eyeball for the swollen muscles and tissues and reduces the appearance of the "bulging eyes."

There are risks associated with orbital decompression. The procedure can lead to the development of double vision or vision loss. For that reason, Wulc prefers to do one side at a time. About three months after decompression surgery, the eyes can be straightened and eyelids adjusted.

For general information on thyroid disease and thyroid eye disease:

American Association of Clinical Endocrinologists, public website

American Thyroid Association

The Hormone Foundation

National Graves' Disease Foundation