Proptosis (Bulging Eye Disease)

Proptosis, also known as exophthalmos, is a bulging of one or both of the eyes. You can see proptosis when you can see the white part of the eye between the iris and the upper eyelid. A variation in the eye protrusion symmetry of more than 2 millimeters is considered abnormal.

It's normal anatomy for some people, but bulging eyes are typically a result of a health condition. Up to 50% of people diagnosed with Graves' disease, the most common cause, develop thyroid eye disease. Proptosis is not life-threatening but can be a symptom of serious disease, including cancer.

This article explains the causes of bulging eye and how they are diagnosed and treated.

Proptosis Symptoms

The main symptom of proptosis is an abnormal protrusion (bulging) of the eyes.

Proptosis can result in the bulging out of one eye (unilateral) or both eyes (bilateral). Other symptoms that can accompany bulging eyes include:

• Difficulty fully closing the eyes during sleep
• Difficulty fully closing the eyes while blinking
• Dryness of the cornea
• Discomfort
• Scarring
• Difficulty moving the eyes
• The perception among others that you are staring

What Causes Bulging Eyes?

The most common cause of bilateral bulging eyes is a thyroid condition known as Graves' disease. In Graves' disease, swelling, fibrosis, and scarring of the tissue behind the eye muscles surrounding the eye may occur. This crowds the bony orbit where the eye sits, causing the eyes to bulge forward.

Causes of proptosis can be evaluated on the basis of whether one or both eyes are affected, and the age and history of the person involved. Thyroid eye disease, for example, is more likely in females at older ages than it is in males or younger people.

Certain tumors may be more likely in children under age 5, while lymphoma or leukemia may be more likely in older children and adults.

Other causes can include:

• Sinus infection that has spread into the orbit, creating an abscess
• Trauma
• Inflammation
• Arteriovenous malformations

Glaucoma present from birth (primary infantile glaucoma) can also cause the eyes to enlarge.

Diagnosing Proptosis

When a person develops proptosis, especially if it comes on suddenly or is in only one eye, medical testing should be done immediately. This can be a sign of a serious medical condition.

Bulging that occurs rapidly (over a few days) suggests different causes than bulging that has developed slowly over the years:

• Rapid bulging in only one eye may be due to bleeding in the eye socket, which can occur after surgery or injury, or infection or inflammation of the eye socket.
• Bulging that develops slowly in both eyes suggests Graves' disease.
• Bulging that develops slowly in one eye may be due to a tumor in the eye socket.

Your healthcare provider will start by taking your medical history and doing a physical exam. They may ask you:

• How long the bulging has been present
• Whether the bulging seems to be getting worse
• If you have other eye symptoms, such as dryness, increased tears, double vision, loss of vision, irritation, or pain
• Whether you've been having symptoms such as the inability to tolerate heat, increased sweating, involuntary shaking movements (tremors), anxiety, increased appetite, diarrhea, palpitations, and weight loss (common symptoms of Graves' disease)

Your healthcare provider will examine your eyes for redness, sores, and irritation using a slit lamp (a device used to examine the eye under high magnification). If your eyelids move as fast as your eyeballs when you look down or appear to be staring, it could indicate Graves' disease.

Your healthcare provider may also measure the degree of bulging with a ruler or a special instrument called an exophthalmometer. They may do more testing if measurements are outside normal ranges, especially if the bulging only affects one eye.

Tests may include:

• Magnetic resonance imaging (MRI)
• Blood tests
• Ultrasound
• Biopsy

Proptosis Treatment

A main symptom of proptosis is dryness of the eye. Because the eyelids may not be able to close completely during normal blinking or sleeping, the cornea may dry out significantly. This dryness is uncomfortable and can cause scarring, which can lead to permanent vision loss.

Your healthcare provider may prescribe artificial tears or gels to lubricate the eye to alleviate discomfort and protect the cornea from severely drying out. You can also wear patches while you sleep sleeping to keep your eyes moist.

Other treatments depend on the cause of bulging:

• If the cause is an infection, antibiotics are prescribed.
• In the case of Graves' disease, medications to treat that condition may lessen eye bulging over time.
• Corticosteroids, like prednisone, may help control swelling caused by Graves' disease or orbital pseudotumor.

In January 2020, the FDA approved Tepezza (teprotumumab), the first drug approved for thyroid eye disease.

In some cases of bulging eyes, surgery may be a necessary part of treatment. Surgery is indicated when:

• A tumor causes proptosis
• Proptosis is causing double vision
• Lubrication is not sufficiently treating eye dryness

Surgery may also be done for aesthetic reasons. Surgical techniques for treating proptosis continue to improve and provide better aesthetic outcomes than before.

Summary

Proptosis is a bulging of the eyes typically caused by a health condition. The most common reason is Graves' disease, but other causes including cancer are possible.

In most cases, proptosis can be treated successfully with medications. Treatment may take time. For example, in most cases, symptoms of thyroid eye disease (including bulging eyes) last up to two years and resolve after treatment. Diagnosing the correct cause is key, though, and some conditions may require surgery or other complex intervention.