What Do Bulging Eyes Look Like and What Causes Them?

Bulging eyes look exactly how the name suggests: one or both eyeballs sit noticeably farther forward in the eye socket than normal, giving a wide, staring appearance even when the face is relaxed. Doctors call this proptosis or exophthalmos, and it can stem from dozens of different conditions, from autoimmune thyroid disease to infections to tumors growing behind the eye. The appearance can range from barely perceptible to dramatic, and the causes span nearly every category of disease.

How Bulging Eyes Actually Look

The hallmark is visible white (sclera) above or below the colored part of the eye when looking straight ahead. In a person without proptosis, the upper eyelid normally covers a small sliver of the iris, and little to no white shows above or below it. When an eye bulges forward, that relationship changes: more sclera becomes visible, the eyelids may not close completely, and the person looks perpetually startled or intense. Other signs that often accompany the protrusion include puffy or swollen eyelids, redness of the conjunctiva (the clear membrane over the white of the eye), tearing, and a sensation of pressure or fullness behind the eye.

Bulging can affect one eye or both. When both eyes are involved, it often points toward a systemic condition like thyroid disease. When only one eye sticks out, the cause is more likely something localized, such as an infection, a tumor, or a vascular problem on that side. The direction the eye is pushed can also be a clue: a mass growing behind the eye pushes it straight forward, while a mass off to one side may push the eye in the opposite direction.

What Counts as Abnormal

Eye protrusion is measured with a device called a Hertel exophthalmometer, which gauges how far forward the eye sits relative to the bony rim of the socket. Normal values differ by sex and ethnicity. A study of 681 American adults found that mean protrusion was about 16.5 mm in white men and 18.5 mm in Black men, with upper normal limits of roughly 21.7 mm and 24.7 mm respectively; for white women, the mean was about 15.4 mm and for Black women about 17.8 mm.¹ A study from northeast China reported a lower overall mean of about 15 mm, with upper normal limits around 18.8 to 19.0 mm.² These differences matter because a reading of 22 mm might be perfectly normal for one person and clearly abnormal for another.

Beyond the absolute number, a difference of more than 2 mm between the two eyes is considered suspicious even if both readings fall within the normal range. Age can also shift the numbers: protrusion tends to increase slightly with age in some populations. Factors like severe nearsightedness can make an eye appear to bulge as well, because a highly elongated eyeball physically sticks out farther in the socket.³ This kind of apparent protrusion without an underlying disease is sometimes called pseudoproptosis.

Thyroid Eye Disease, the Most Common Cause in Adults

If you see someone with both eyes bulging, Graves’ disease is the most likely explanation. Graves’ disease is an autoimmune condition in which the immune system attacks the thyroid gland, causing it to overproduce hormones. But the same immune response can also target tissues behind the eyes, causing the muscles and fat in the eye socket to swell. That swelling pushes the eyeball forward. The condition is known as thyroid eye disease, and it accounts for the vast majority of bilateral proptosis in adults.⁴

Thyroid eye disease often follows a predictable arc. There is an active inflammatory phase, typically lasting one to three years, during which the eyes become progressively more swollen, red, and prominent. This is followed by a stable or “burned-out” phase in which the inflammation subsides but the physical changes may persist. Even in the chronic phase, patients report ongoing problems with their appearance, vision, and emotional well-being.⁵

Smoking is the single strongest modifiable risk factor for developing thyroid eye disease. A systematic review found strong evidence that smoking causes the condition to develop and makes it progress more aggressively. Smokers also tend to respond more poorly to treatment.⁶ Quitting smoking is one of the clearest things you can do to reduce your risk if you have Graves’ disease.

Infections That Push the Eye Forward

Orbital cellulitis, a bacterial infection of the soft tissues behind the eye, is one of the most common causes of sudden, one-sided eye bulging, especially in children. It typically starts as a sinus infection that spreads into the eye socket. The affected eye becomes red, swollen, painful, and difficult to move, and the person often has a fever. This is a medical emergency because the infection can threaten vision and, in rare cases, spread to the brain.

In children, orbital cellulitis is the leading cause of proptosis overall. A retrospective study at a tertiary children’s hospital reviewed cases of radiographically confirmed orbital cellulitis over a seven-year period, underscoring how frequently this infection occurs in the pediatric population.⁷ The usual treatment is intravenous antibiotics, and sometimes surgical drainage if an abscess forms.

Tumors and Growths Behind the Eye

Any mass that takes up space inside the eye socket can push the eyeball forward. These range from benign growths like hemangiomas (tangles of blood vessels) and dermoid cysts to aggressive cancers. In adults, the most common malignant orbital tumors are lymphomas and cancers that have spread from elsewhere in the body, particularly breast and lung cancer. A review of 38 patients with metastatic orbital tumors found that proptosis, double vision, limited eye movement, and a palpable mass were among the most common signs.⁸

In children, the tumor landscape is different. A study of 57 pediatric proptosis cases found that after orbital cellulitis, the most frequent causes included optic nerve glioma, rhabdomyosarcoma (a soft-tissue cancer), metastatic neuroblastoma, and orbital neurofibroma.⁹ Rhabdomyosarcoma in particular tends to grow rapidly, and a child whose eye starts bulging over just a few weeks needs urgent evaluation. Speed of onset is one of the most useful clues clinicians use to narrow the diagnosis: proptosis that develops over hours to days suggests infection or bleeding, over weeks suggests a fast-growing tumor or aggressive inflammation, and over months points toward slower-growing tumors or thyroid disease.

Inflammatory Conditions That Mimic Tumors

Not every mass behind the eye is a tumor. Idiopathic orbital inflammatory disease, sometimes called orbital pseudotumor, is a condition where the immune system attacks orbital tissue for no obvious reason, producing swelling that looks and feels like a tumor on imaging. It can cause proptosis, eyelid swelling, pain, and blurry vision.¹⁰ The condition often responds dramatically to corticosteroids, which helps distinguish it from true cancer.

Orbital pseudotumor sometimes occurs alongside systemic autoimmune conditions such as rheumatoid arthritis, Crohn’s disease, and lupus.¹¹ When the pseudotumor doesn’t respond to steroids or keeps coming back, doctors look harder for an underlying condition and may escalate to stronger immunosuppressive drugs or radiation therapy.

Vascular Problems and Trauma

Blood vessel abnormalities can also push the eye forward. A carotid-cavernous fistula, an abnormal connection between an artery and a venous channel near the eye, causes blood to flow the wrong way into the veins around the eye. The result is a swollen, red, bulging eye that may have a visible, pulsating quality. Patients often notice a whooshing sound in their head. The initial presentation frequently includes decreased vision, bulging of the conjunctiva (chemosis), difficulty moving the eye, and proptosis.¹²

Trauma is another route. A blow to the face can cause bleeding behind the eye, a condition called retrobulbar hemorrhage. Blood pools in the confined space of the socket and pushes the eye outward, often within minutes. This is a true emergency, because the rising pressure can cut off blood supply to the optic nerve. A case series described how retrobulbar hemorrhage following blunt orbital trauma can rapidly evolve from visual impairment to permanent vision loss if the pressure isn’t relieved quickly.¹³ Treatment involves cutting open the outer corner of the eyelids or drilling into the bony wall of the socket to relieve the pressure.

Congenital Causes

Some children are born with orbits that are abnormally shallow, making their eyes appear to protrude from birth. This occurs in several craniosynostosis syndromes, conditions in which the skull bones fuse too early during development. In Crouzon syndrome and Apert syndrome, for example, the shallow orbits give the eyes a prominent, wide-set appearance that can range from mild to severe enough that the eyelids cannot fully close over the eyes.¹⁴ These children often need staged surgeries over many years to reshape the skull and protect the eyes.

Why Bulging Eyes Can Threaten Vision

Proptosis is more than a cosmetic issue. When the eye sits too far forward, the eyelids may not close completely, especially during sleep. This exposes the cornea to drying, which can lead to corneal ulcers and scarring. Patients with even moderate proptosis often complain of gritty, dry, irritated eyes, and they frequently need lubricating drops or ointments to prevent damage.

The more dangerous complication involves the optic nerve. In thyroid eye disease, swollen muscles at the back of the eye socket can squeeze the optic nerve at the orbital apex, a condition called dysthyroid optic neuropathy. Over 90% of these cases result from direct nerve compression by the enlarged muscles, while the remainder involve stretching of the nerve without compression.¹⁵ Signs include color vision changes, reduced sharpness of vision, and visual field loss. Without treatment, the damage can become permanent.

Treatment for Thyroid Eye Disease

For decades, treatment of thyroid eye disease was limited to corticosteroids to tamp down inflammation, radiation to the orbit, and surgery for severe cases. That changed in 2020 with the approval of teprotumumab, a drug that blocks a specific receptor involved in the inflammatory process behind the eye. In clinical trials, it reduced proptosis, double vision, and inflammation, and it improved quality of life. Since its approval, more than 5,800 patients have been treated, and both the American Thyroid Association and the European Thyroid Association have recommended it as first-line therapy for moderate to severe thyroid eye disease with prominent proptosis or double vision.¹⁶

That said, teprotumumab is expensive, not universally available, and not right for every patient. Some people experience hearing changes or worsening of inflammatory bowel disease during treatment.¹⁷ It remains the only FDA-approved drug specifically for thyroid eye disease, so for patients who cannot take it, corticosteroids and orbital radiation are still the mainstay of medical management.

When Surgery Is Needed

When medical treatment isn’t enough, or when proptosis is severe enough to endanger the optic nerve or the cornea, orbital decompression surgery can make room for the swollen tissue by removing bone from the walls of the eye socket, removing orbital fat, or both. The goal is to let the contents of the socket expand into adjacent spaces, allowing the eye to settle back into a more normal position.¹⁸

How much the eye recedes depends on the technique. A meta-analysis comparing different approaches found that fat removal alone reduced protrusion by about 3.5 mm on average, while removing one bony wall achieved roughly 3.9 to 4.0 mm of reduction. Balanced two-wall decompression yielded about 5.2 mm, and three-wall decompression achieved the most, around 5.8 mm.¹⁹ More aggressive techniques produce bigger reductions but also carry higher risks of complications like double vision and numbness. No single approach has been proven superior in randomized trials, so the choice depends on how much recession is needed and the surgeon’s experience.²⁰

Surgery is generally staged: doctors wait until the thyroid eye disease has been stable for at least six months before operating. If a patient needs multiple procedures (decompression, strabismus surgery to correct eye alignment, and eyelid surgery to improve closure and appearance), they are done in that order, with healing time between each stage.

How Childhood Proptosis Differs

The cause of bulging eyes in children is dramatically different from adults. While thyroid disease dominates the adult picture, infections and cancers are far more common in kids. A review of pediatric proptosis found that orbital cellulitis was the single most frequent cause, followed by thyroid disease and then several types of tumors including optic glioma and rhabdomyosarcoma.⁹ The key takeaway for parents is that any unexplained protrusion of a child’s eye warrants prompt medical evaluation. In many pediatric cases, the eye bulges rapidly, and early diagnosis and treatment can be the difference between a good outcome and a devastating one.

The Emotional and Social Toll

Bulging eyes change how people see themselves and how others see them. Patients with thyroid eye disease consistently report that the condition affects their quality of life well beyond the active inflammatory phase. Even after the disease has stabilized and the medical emergency has passed, many still feel self-conscious about their appearance, avoid social situations, and experience depression or anxiety. A study of chronic thyroid eye disease patients in the United States confirmed that vision impairment, appearance concerns, and psychosocial distress persisted long after the acute disease had burned out.⁵

This emotional burden is often underestimated by doctors and even by patients’ families. The appearance change can be so striking that strangers stare, and well-meaning people may ask if the patient is feeling all right. Support groups and mental health counseling can help, and it is worth knowing that rehabilitative surgeries (decompression, eyelid repositioning) can significantly improve both function and appearance even years after the initial diagnosis.

When to Seek Urgent Help

Not all proptosis is an emergency, but certain patterns are. You should go to an emergency room if an eye suddenly bulges outward after trauma, if proptosis develops rapidly alongside fever and severe pain (suggesting orbital cellulitis), or if you notice your vision dimming or your color vision changing alongside an already bulging eye (suggesting optic nerve compression). Retrobulbar hemorrhage after a facial injury can cause irreversible blindness within hours if the pressure is not released.¹³ Gradual, painless protrusion still deserves evaluation, but the timeline is less urgent. See an ophthalmologist or your primary care doctor within a few weeks rather than hours.

One practical thing you can do at home is compare old photographs. Because proptosis often develops slowly, people sometimes don’t notice the change until it becomes quite advanced. Looking back through photos from different years can reveal a gradual shift that might otherwise go unrecognized, and can help your doctor gauge how long the process has been developing.