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Bulging or protruding of one or both eyes is called proptosis or exophthalmos. Exophthalmos is usually used when describing bulging eyes caused by Graves disease, a disorder causing overactivity of the thyroid gland (hyperthyroidism—see Hyperthyroidism). Bulging eyes are not the same as prominent eyes. Some disorders that may change the appearance of the face and eyes but that do not cause true eye bulging include Cushing disease (see Cushing Syndrome) and severe obesity.
Bulging sometimes causes other symptoms. The eyes may be dry and irritated (which causes watering) because the bulging may prevent the eyelids from closing properly. Also, people may blink less often or may appear to stare. Depending on the cause of bulging, people may have other symptoms such as double vision or difficulty focusing on objects. If bulging is prolonged, the optic nerve is stretched, which may impair vision. Vision may also be impaired if the disorder causing bulging also presses on the optic nerve.
The most common cause is Graves disease, which causes swelling of tissue behind and around the eye, pushing the eyeball forward.
Other causes are uncommon. They include tumors, bleeding, infections, and, rarely, inflammation of structures within the orbit without infection (called orbital pseudotumor—see Inflammation of the Orbit). Glaucoma that is present from birth can cause the eyes to enlarge, which may seem to look similar to eyes that are pushed forward (see Primary Infantile Glaucoma).
The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.
Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause for eye bulging and the tests that may need to be done (see Table: Some Causes and Features of Bulging Eyes).
How long the bulging has been present
Whether both eyes are bulging
Whether bulging seems to be getting worse
Whether the person has other eye symptoms, such as dryness, increased tear formation, double vision, loss of vision, irritation, or pain
Whether the person has symptoms of hyperthyroidism, such as inability to tolerate heat, increased sweating, involuntary shaking movements (tremors), anxiety, increased appetite, diarrhea, palpitations, and weight loss
Bulging that has developed rapidly (over a few days) suggests different causes than bulging that has developed over years. Rapid bulging in only one eye suggests bleeding in the eye socket (orbit), which can occur after surgery or injury, or infection or inflammation of the eye socket. Bulging that develops slowly suggests Graves disease (when it affects both eyes) or a tumor in the eye socket (when it affects one eye).
The physical examination is focused on the eyes. Doctors examine the eyes for redness, sores, and irritation using a slit lamp (an instrument that enables a doctor to examine the eye under high magnification—see Figure: What Is a Slit Lamp?). They check whether the eyelids move as fast as the eyeball when the person looks down and check for staring. Slow eyelids and staring could indicate Graves disease.
Doctors may also check for other signs that could indicate hyperthyroidism, such as increased heart rate or blood pressure, tremors, and a swollen or tender thyroid gland in the neck.
Some Causes and Features of Bulging Eyes
When bulging leads to severe dry eyes, lubrication with artificial tears is needed to protect the cornea (the clear layer in front of the iris and pupil). Sometimes if lubrication is not sufficient, surgery to provide better coverage of the eye surface or to reduce bulging may be needed.
Other treatments depend on the cause of bulging. For example, antibiotics are given for infections. Bulging due to Graves disease is not affected by treatment of the thyroid condition but may lessen over time. Corticosteroids (for example, prednisone) may help control swelling due to Graves disease or orbital pseudotumor. Tumors must be surgically removed.
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