Formula Medical Group
Apple Valley, CA

James Krider, MD

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Bulging Eyes - Proptosis

An overactive thyroid gland (hyperthyroidism) can result in bulging eyes

Shakespeare called the eyes "the windows to the soul." Certainly the eyes, more than any other facial feature, provide insight into both health and personality characteristics. During a physical examination, a doctor carefully examines the eyes — the only place in the body where blood vessels can be directly observed — for signs of many diseases, including diabetes, high blood pressure, and circulatory disorders.

The eyes also convey a wide range of emotions and responses — everything from affection and pleasure to anger and puzzlement. People who "read" body language maintain that the eyes are almost perfect lie detectors, and that few people can be untruthful without having their eyes give them away.

Some people have very prominent eyes, giving them a "goggly" or popeyed appearance. This is usually an inherited characteristic, and not a symptom of disease. But a change in the prominence, position, or shape of the eyes may indicate an underlying disease, warranting prompt medical attention.

Causes of bulging eyes

Cancer and tumors
The protrusion or bulging of only one eye often signifies a tumor or cancer growing either in the eye itself or, more commonly, in the space behind the eyeball. Eye cancer is relatively rare, with retinoblastoma being the most common. This is a congenital cancer that is present at birth or develops shortly thereafter. The tumor arises in the retina — the lining at the back of the eye. In addition to a bulging of the affected eye, symptoms include crossed eyes and the appearance of a gray or yellow spot in the pupil. Both eyes may be affected.

The second most common type of eye cancer is an unusual form of melanoma, a cancer of pigment cells. Most melanoma arises in the skin,

and then spreads to other parts of the body. Ocular melanoma, however, starts in the pigment-forming cells (melanocytes) of the iris or other structures of the eye.

Pronounced bulging may be caused by cancers arising in the socket or other structures around the eye. One of the more common is a cancer called rhabdomyosarcoma, which forms in the muscles that control movement of the eyeball. Certain types of brain cancer may spread to the eye, causing bulging and other symptoms. Similarly, cancers in other parts of the face or head — for example, an invasive squamous cell skin cancer — may also spread to the eye.

Glaucoma is a serious eye disorder characterized by increased pressure inside the eyeball. There are several different types of glaucoma, and most do not actually alter the outward appearance of the eye. An exception is congenital glaucoma, a rare condition that is present at birth or early in life. The glaucoma is caused by a structural defect that prevents the outflow of aqueous, the gellike fluid inside the eye. This causes a buildup of pressure and enlargement and an outward bulging of the eyeball.

Bleeding behind the eye can cause bulging of the eyeball itself. Sudden bulging of an eye may be caused by rupture of an A-V (arteriovenous) malformation near the eye. This type of bleeding usually produces a characteristic sound called a bruit, which a doctor can hear through a stethoscope.

Infection or inflammation of the eye and surrounding structures can produce bulging. One particularly serious type is a condition called orbital cellulitis, an infection that involves the area surrounding the eyeball. The infection may arise in nearby tissues, such as the nasal sinuses or even an abscessed tooth.

A bulging eye following a head injury indicates possible bleeding behind the eye or other damage to nearby structures. Other symptoms may include headache, changes in consciousness, and bleeding from the nose, ears, or mouth. All warrant an immediate trip to the emergency room.

Thyroid disease
An overactive thyroid gland (hyperthyroidism) is the most common cause of bulging eyes. The protrusion affects both eyes and develops gradually over a period of weeks or months. The bulging is not due to an enlargement of the eyes themselves; instead, it results from a buildup of fluid in the underlying orbital tissue, thereby pushing the eyeballs forward. Sometimes the eyes become so prominent that it is impossible to close them fully. Since the person does not blink as often as normal and the eyelids cannot fully close, the eyes may become irritated and abnormally dry. In most cases, treating the underlying thyroid disease resolves the eye problem, but the eyes may remain more prominent than in the past. In extreme cases, surgery may be needed to enlarge the orbit and give the eyes a more normal position.

Advice about bulging eyes

  • The positioning or "set" of the eyes varies from person to person, and is largely an inherited trait. Major abnormalities often can be corrected with plastic or reconstructive surgery.
  • Any change in the appearance of the eyes — especially changes in shape, prominence, and movement — should be checked by a doctor. Color changes and spots on the eye should be checked as well.
  • If the eyes are healthy but their appearance is troubling, a consultation with a makeup artist may be helpful. Careful use of eye shadows can make a dramatic difference.
This article was last reviewed October 24, 2005 by Dr. James Krider.
Reproduced in part with permission of Home Health Handbook.
A-V malformations
Brain Cancer
Congenital glaucoma
Eye cancer
Eye hemorrhages
Eye socket infection
Head injuries

Overactive thyroid

Squamous cell cancer

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