- Home
- Knowledge centre
- Eye glossary A–Z
- Exophthalmos: Bulging Eyes, Causes, Symptoms and Treatment
Exophthalmos: Bulging Eyes, Causes, Symptoms and Treatment
Medically reviewed by {{surgeon}}, {{surgeon's title and specialty}}, on {{review date}}. Last updated {{date}}.
Exophthalmos (noun; also called proptosis): exophthalmos is the forward bulging of one or both eyes out of the eye socket (the orbit). It happens when something inside the orbit, such as swollen muscle and fat, a growth, an infection or a blood vessel problem, takes up more room and pushes the eye forward. In adults the most common cause is thyroid eye disease, usually linked to Graves' disease, but sudden or one-sided bulging with pain, fever or lost vision is an emergency.
Exophthalmos: key facts
- Other names
- Proptosis, bulging eyes, protruding eyes. "Exophthalmos" comes from the Greek for "bulging eyes"
- What it is
- A sign, not a disease in itself: the eye is pushed forward because the contents of the bony orbit have increased
- One eye or both?
- Both eyes usually points to a general cause such as thyroid eye disease; one eye more often points to a local cause such as a tumour, infection or blood vessel problem
- Most common cause in adults
- Thyroid eye disease (Graves' orbitopathy)
- How it is measured
- With a Hertel exophthalmometer (a small handheld device that measures how far the front of the eye sits in front of the orbital rim), plus CT or MRI scans
- Urgent warning signs
- Sudden bulging, pain, fever, double vision, a drop in vision, or an eye that cannot close
- Who treats it
- An ophthalmologist (often an oculoplastic or orbital specialist) together with an endocrinologist when the thyroid is involved; at Laser Istanbul Clinic, eyelid and oculoplastic assessment is with Prof. Dr. Ahmet Satıcı
What is exophthalmos?
Exophthalmos is a medical term for eyes that protrude forward out of the orbit. The StatPearls medical reference describes it as the protrusion of one or both eyes anteriorly out of the orbit, caused by an increase in the contents of the bony orbit. The eye socket is a rigid cone of bone, so if its contents (the eye itself, the eye muscles, fat, nerves and blood vessels) swell or something new grows inside it, the only way out is forward.
Exophthalmos or proptosis: what is the difference?
In everyday medical use the two words mean the same thing. "Proptosis" is the broader, more modern term and is used for forward displacement of the eye from any cause. "Exophthalmos" is often kept for bulging caused by thyroid eye disease, but the terms are used interchangeably, and both are correct for this page.
Is it the same as having "big eyes" or a "staring look"?
Not always. A person can look as though their eyes bulge when the eyelids are simply sitting too high (eyelid retraction), exposing more of the white of the eye. This is common in thyroid eye disease, where eyelid retraction occurs in up to about 90% of patients, and it can exist with or without true forward displacement of the eye. Doctors call a bulging look without real forward displacement "pseudoproptosis". An examination and measurement tell the two apart.
What is a normal eye position?
There is no single normal number. Normal exophthalmometer readings vary with age, sex and ethnic background; a 2022 study of 1,000 North Indian adults, for example, found an average reading of 14.9 mm with a range from 8 to 22 mm, while a 2026 study of a Japanese population found an average of 15.6 mm. Because of this, doctors judge a reading against the person's own background, compare the two eyes, and look at whether the position has changed over time. A change, or an eye that looks different from the other, matters more than one reading on its own.
What causes exophthalmos?
Causes fall into a few groups. Thyroid disease is by far the most common in adults.
| Cause | How it pushes the eye forward | Usually affects |
|---|---|---|
| Thyroid eye disease (Graves' orbitopathy) | The immune system inflames and swells the eye muscles, fat and connective tissue in the orbit | Both eyes, often unevenly; one eye sometimes |
| Orbital cellulitis | A bacterial infection, often spreading from the sinuses, swells the tissue behind the eyelid | Usually one eye; emergency |
| Orbital inflammation (non-thyroid) | Inflammation of orbital tissue without infection, sometimes related to other immune conditions | One or both eyes |
| Tumours and growths | A benign or malignant growth in the orbit takes up space; examples include a cavernous haemangioma (a benign blood-vessel tumour) | Usually one eye, gradually |
| Blood vessel problems | Abnormal vessels or a bleed behind the eye increase the volume or pressure in the orbit | Usually one eye |
| Injury | Bleeding or swelling inside the orbit after trauma | One eye |
| Other | Inherited skull and orbit conditions, and in children some tumours and cancers, including leukaemia | Varies |
Thyroid eye disease: the most common cause
Thyroid eye disease (TED, also called Graves' ophthalmopathy or Graves' orbitopathy) is an autoimmune condition. The immune system attacks tissue around the eyes, the orbital fibroblasts become active, and the eye muscles and orbital fat swell. Several points are worth knowing:
- It is linked to Graves' disease. Graves' disease causes about 4 in 5 cases of overactive thyroid, according to the NHS. The American Thyroid Association says about one in three people with Graves' disease develop eye symptoms; EyeWiki, the American Academy of Ophthalmology's clinical wiki, gives about half. TED can rarely occur when the thyroid blood tests are normal or low.
- It affects women more than men (about 5 to 1 in EyeWiki's summary), and the median age at diagnosis is 43, although it can occur from childhood to old age.
- Smoking makes it more likely and more severe. EyeWiki calls smoking the most consistently linked risk factor, and the American Thyroid Association says secondhand smoke counts too.
- It has an active and a settled phase. The inflammatory (active) phase lasts roughly 6 to 18 months; after that the disease settles, and the eyes improve gradually, though some changes can be permanent.
- Eyes can be affected before, during or after the thyroid problem is found. Symptoms usually appear within the first year after Graves' diagnosis, according to the American Thyroid Association.
The eyes in TED often show more than bulging: eyelid retraction (up to about 90%), double vision, redness and swelling of the lids, and dryness. In a classic 1994 survey, about 60% of patients had exophthalmos and about 40% had restricted eye muscle movement.
Orbital cellulitis: the infection you must not miss
Orbital cellulitis is an infection of the soft tissue behind the eyelid, most often bacterial and often spreading from the sinuses. It typically causes a bulging, painful, red and swollen eye, pain when the eye moves, and fever. EyeWiki states it needs hospital admission and intravenous antibiotics, and that with prompt treatment the outlook is excellent. Delay can be dangerous. If a bulging eye comes with fever, pain on eye movement or illness, it is an emergency, especially in a child.
Tumours, inflammation and blood vessel problems
A growth in the orbit usually pushes the eye forward slowly and often on one side. Benign tumours such as cavernous haemangioma and malignant tumours both occur; imaging is needed to tell them apart. Inflammatory conditions and vascular anomalies also cause bulging, which is why a new bulge in just one eye always deserves a specialist assessment and imaging.
What are the symptoms of exophthalmos?
Bulging itself is the main sign, but the problems it causes in the eye are what most people notice first. Typical symptoms and signs include:
| Symptom or sign | What it can mean |
|---|---|
| Eyes that look larger, more prominent or "staring" | Forward displacement of the eye, eyelid retraction, or both |
| Gritty, dry, burning or watering eyes | The surface of the eye is exposed to air; dry eye and surface damage |
| Redness and swelling of the eyelids, puffiness around the eyes | Active inflammation, as in TED |
| Pain or pressure behind the eye, especially when moving it | Active inflammation or infection |
| Double vision | Swollen or stiff eye muscles no longer move the eyes in step |
| Eyelids that do not close fully | Exposure of the cornea (see below) |
| Sensitivity to light | Surface irritation or corneal damage |
| Blurred, dim or lost colour vision | The optic nerve may be compressed: urgent |
Why exophthalmos can damage vision
Two complications are the reason doctors take bulging eyes seriously:
- Corneal exposure. If the eyelids cannot close over the front of the eye (lagophthalmos), the cornea dries out and can become inflamed, ulcerated or infected. EyeWiki describes exposure keratopathy in thyroid eye disease as an ocular emergency and a major cause of vision loss.
- Optic nerve compression. In a small number of patients (fewer than 5% in TED, according to EyeWiki), swollen tissue squeezes the optic nerve, causing dysthyroid optic neuropathy. It shows up as dimming or blurring of vision, loss of colour vision or a changed pupil reaction, and it is also an emergency that needs urgent treatment.
How is exophthalmos diagnosed?
Diagnosis answers two questions: is the eye really displaced, and what is pushing it? The steps are usually:
History and examination
The doctor asks how long the bulging has been present, whether it is in one eye or both, and about thyroid symptoms, smoking, injury, pain and vision. They look at the position of the eyelids, eye movements, how well the eyes close, and the front of the eye with a slit lamp.
Exophthalmometry
A Hertel exophthalmometer measures how far each eye sits forward, in millimetres. Repeated measurements track change over time.
Vision, colour vision, pupil and visual field tests
These check the optic nerve and are essential if compression is suspected.
Blood tests
The NHS notes that a GP can arrange blood tests to assess thyroid function; an abnormal result leads to further tests to find the cause, such as thyroid antibodies.
Imaging
CT shows the bone and tissue density of the orbit and, in thyroid disease, the enlarged muscle bellies with the tendons spared; MRI shows how much water the tissue holds, which relates to inflammation. In any one-sided or unexplained case, imaging is how a tumour or vascular problem is found.
Clinical Activity Score (CAS)
In TED, doctors score signs such as pain, redness and swelling out of 7; a score of 3 or more indicates active disease, which affects treatment choice.
Further routine measurements and scans that eye specialists use are described on our page about eye examinations and diagnostic tests.
How is exophthalmos treated?
Treatment depends on the cause. Treating the cause is first, and protecting the eye is always part of it.
If the cause is thyroid eye disease
Care is shared between an endocrinologist (who manages the thyroid) and an ophthalmologist (who manages the eyes). The 2021 European guidelines (EUGOGO) group treatment by severity:
| Severity | Typical approach |
|---|---|
| Mild | Control risk factors (stop smoking, keep thyroid levels stable), lubricating drops, and selenium supplements in areas where selenium intake is low; many mild cases settle with time |
| Moderate to severe, active | Intravenous methylprednisolone (a steroid) in 12 weekly infusions, 4.5 g in total, usually with mycophenolate; further options include orbital radiotherapy and biologic drugs |
| Sight-threatening (optic nerve compression, corneal breakdown) | High-dose intravenous steroid at once and, if there is no quick response, urgent orbital decompression surgery |
| Settled disease with leftover changes | Rehabilitative surgery |
Some details:
- Smoking and thyroid control. EyeWiki states that stopping smoking and keeping the thyroid level normal ("euthyroid") help prevent worsening and shorten the active phase. The EUGOGO guideline also lists radioactive iodine treatment of the thyroid as a risk factor to discuss with your endocrinologist.
- Self-care. The American Thyroid Association lists sunglasses, lubricating drops and sleeping with the head raised.
- Teprotumumab. In 2020 the US FDA approved this drug (Tepezza), an IGF-1 receptor blocker given as eight intravenous infusions three weeks apart. In the 2020 NEJM trial, 83% of patients on teprotumumab had a meaningful reduction in proptosis at week 24 versus 10% on placebo. The FDA label lists hearing impairment, high blood sugar and bowel inflammation among its warnings, and requires contraception during treatment and for 6 months after. It is prescribed by specialists, and availability varies by country.
- Orbital decompression. A surgeon removes bone or fat to give the eye more room. In a 2026 study of secondary decompression, average eye position fell by 4.5 mm; 5 of 17 patients developed new double vision, a known risk of the operation.
- Order of surgery. After the disease has settled, EyeWiki advises an order: orbital decompression first, then eye-muscle (squint) surgery for double vision, then eyelid surgery for retraction or exposure, because each step changes the next.
If the cause is infection
Orbital cellulitis is treated in hospital with intravenous antibiotics, and surgery if an abscess forms or antibiotics do not work within 24 to 48 hours (EyeWiki).
If the cause is a tumour, inflammation or a vessel problem
Treatment follows the diagnosis: observation of a harmless growth, surgery, medication such as steroids for non-infectious inflammation, or radiotherapy and other cancer treatment. This is directed by an orbital specialist after imaging, and often a biopsy.
Protecting the eye while it is treated
Whatever the cause, doctors protect the cornea first: preservative-free lubricating drops by day, ointment at night, taping or other measures when the lids do not close, and treatment of any eyelid retraction. Our team deals with the eyelid side of these problems.
Treatment with us: if your bulging eyes come with eyelid problems (a high, retracted lid, a lid that will not close, or a lid position that has changed), eyelid and oculoplastic surgery is led by Prof. Dr. Ahmet Satıcı. Thyroid control stays with your own endocrinologist, and a bulging eye that is new, painful or one-sided needs a local emergency assessment first. Send us your reports and scans and the surgeon will tell you whether treatment in Istanbul is right for you.
When to see a doctor about bulging eyes
Seek emergency care the same day if you or your child have:
- sudden bulging of an eye, or bulging with pain, fever, or a red, swollen eyelid
- pain when you move the eye
- a drop in vision, dimming or loss of colour vision
- new double vision with eye bulging
- an eye that will not close, with pain or redness
- bulging after a head or eye injury
Book an appointment soon (within days to weeks) if:
- your eyes have gradually become more prominent, or one eye looks different from the other
- you have an overactive thyroid or Graves' disease and develop dry, gritty, red or puffy eyes
- friends or family comment that your eyes look "staring" and you are not sure why
- you smoke and have thyroid disease and eye symptoms: ask for help to stop, because it affects your eyes
If you already have a diagnosis and want a second opinion on eyelid or surgical options, you can send your scans for review before you travel.
Frequently asked questions
Exophthalmos is the medical term for one or both eyes bulging forward out of the eye socket. It is a sign of another problem, most often thyroid eye disease in adults, and the word means the same as proptosis.
In practice there is none. Proptosis is the more general term for any forward displacement of the eye, while exophthalmos is often used when the cause is thyroid disease. Doctors use them interchangeably.
Thyroid eye disease, linked to Graves' disease, is the most common cause in adults. Others include orbital infection (orbital cellulitis), orbital tumours, non-infectious orbital inflammation, blood vessel problems and injury. In one-sided cases the cause is more often local, which is why imaging is needed.
It depends on the cause. Infections can resolve fully with prompt treatment, and mild thyroid eye disease often settles on its own as the disease passes its active phase. When changes remain, they can be improved with medication or surgery, but results vary and no outcome can be promised.
Sometimes. Sudden bulging, pain, fever, double vision or reduced vision can mean orbital cellulitis or optic nerve compression, and need same-day assessment. A slow change in the appearance of the eyes should be checked within days to weeks.
No. Thyroid eye disease is the most common cause in adults, but infection, tumours, inflammation, blood vessel problems and injury also cause it. A person can also have a "staring" look from eyelid retraction without the eye being pushed forward at all (pseudoproptosis).
Yes. Smoking is the best-documented risk factor for developing thyroid eye disease and for it becoming more severe, and secondhand smoke also counts. Stopping smoking is one of the most useful things a person with thyroid eye disease can do.
They can. An eye that does not close fully can develop corneal damage, and in a small number of people with thyroid eye disease the optic nerve is compressed. Both are treatable if found early, which is why sudden changes in vision should be seen urgently.
Usually an ophthalmologist, often with oculoplastic or orbital training, working with an endocrinologist if the thyroid is involved. Eyelid and oculoplastic surgery at Laser Istanbul Clinic is led by Prof. Dr. Ahmet Satıcı.
Sources for the facts on this page
- Exophthalmos. StatPearls (NBK559323), NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK559323/ (definition; checked through Europe PMC record PMID 32644749)
- EyeWiki (AAO). Thyroid Eye Disease. https://eyewiki.org/Thyroid_Eye_Disease
- EyeWiki (AAO). Orbital Cellulitis. https://eyewiki.org/Orbital_Cellulitis
- American Thyroid Association. Thyroid Eye Disease. https://www.thyroid.org/thyroid-eye-disease/
- NHS. Overactive thyroid (hyperthyroidism). https://www.nhs.uk/conditions/overactive-thyroid-hyperthyroidism/
- Bartalena L, Kahaly GJ, Baldeschi L, et al. The 2021 European Group on Graves' Orbitopathy (EUGOGO) clinical practice guidelines for the medical management of Graves' orbitopathy. Eur J Endocrinol 2021;185(4):G43–G67. PubMed: https://pubmed.ncbi.nlm.nih.gov/34297684/
- Douglas RS, Kahaly GJ, Patel A, et al. Teprotumumab for the treatment of active thyroid eye disease. N Engl J Med 2020;382:341–352. PubMed: https://pubmed.ncbi.nlm.nih.gov/31971679/
- US FDA. Tepezza (teprotumumab-trbw) prescribing information. https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/761143s000lbl.pdf
- Bartley GB. Ophthalmopathy associated with autoimmune thyroid disease. Trans Am Ophthalmol Soc 1994. PubMed: https://pubmed.ncbi.nlm.nih.gov/7886878/
- Revankar S, Mehta A. Determination of exophthalmometry values in the North Indian population. Indian J Ophthalmol 2022. PubMed: https://pubmed.ncbi.nlm.nih.gov/35918977/
- Nakaji E, et al. Exophthalmometry values of a contemporary Japanese population with/without Graves' disease. Endocr J 2026. PubMed: https://pubmed.ncbi.nlm.nih.gov/41297932/
- Cheng et al. Secondary inferomedial orbital decompression. Indian J Ophthalmol 2026. PubMed: https://pubmed.ncbi.nlm.nih.gov/42671097/
- Abidin NA, Ismail IA, Jamil SN, Mustafa N. When patients present with bulging eyes: a case series of proptosis. Malays Fam Physician 2025. PubMed: https://pubmed.ncbi.nlm.nih.gov/40662124/
Bulging eyes or eyelid changes you are worried about?
Send us your reports, scans and a few photos. Our surgeon will review them and tell you honestly which treatments may help, and whether treatment in Istanbul makes sense for you, with no obligation.
3 eye surgeons
Your case is reviewed by a named surgeon, not a salesperson. Reply within {{response time}}.
Prof. Dr. Ahmet Satıcı
Doç. Dr. Muhammet Derda Özer
Op. Dr. Aysan Bayram