Exophthalmos is a medical term for a bulging or protruding eyeball or eyeballs.

It is often used interchangeably with the term “proptosis”, which means the same thing.

What causes exophthalmos?

Exophthalmos can be caused by many different conditions. It’s important that the underlying cause is identified so appropriate treatment can be given.

Thyroid eye disease

One of the main causes of exophthalmos in the UK is thyroid eye disease, also known as Graves’ ophthalmopathy.

This is an autoimmune condition that affects around one in every three people with an overactive thyroid gland (hyperthyroidism) caused by Graves’ disease. It is particularly common in women who are 30-50 years of age and people who smoke.

An autoimmune condition is where the immune system (the body’s defence against illness and infection) mistakenly attacks healthy tissue. In the case of thyroid eye disease, the immune system attacks the muscles and fatty tissues around and behind the eye, causing them to become inflamed (swollen).

Graves’ disease is an autoimmune condition in which the thyroid is attacked, leading to an increase in the level of thyroid hormones in your blood. It’s not clear exactly why thyroid eye disease sometimes occurs along with this condition.

Thyroid eye disease can also occasionally affect people with an underactive thyroid gland (hypothyroidism) and, in rare cases, people with seemingly normal thyroid function.

Other causes

Exophthalmos can also have a number of other causes, but these are generally less common than thyroid eye disease.

Other cause of exophthalmos can include:

• an injury to the eyes
• bleeding behind the eyes
• abnormally shaped blood vessels behind the eyes
• an infection of the tissue in the eye socket
• cancerous tumours – such as those caused by neuroblastoma and some soft tissue sarcomas

Exophthalmos can also affect newborn babies if they are born with eye sockets that are shallower than normal.

Other problems associated with exophthalmos

Depending on what is causing your bulging eyes, you may also have other associated symptoms. For example, if exophthalmos is caused by a thyroid eye disease, your eyes may also be:

• inflamed, red and painful
• dry and “gritty”
• tearful
• sensitive to light (photophobia)

You may also experience some double vision.

In severe cases of exophthalmos, you may not be able to close your eyes properly. This can damage your corneas (the transparent tissue that covers the front of your eye) by causing them to dry out.

If your corneas become very dry, an infection or ulcers (open sores) may develop. These could damage your vision if left untreated.

There is also a small risk of the optic nerve (which transmits signals from the eye to the brain) becoming compressed if you have exophthalmos, which may affect your sight permanently if it is not treated quickly.

Seeking medical advice

It’s important to see your GP or an optometrist (optician) if you notice that one or both of your eyes are protruding, as treatment is often more effective if it’s started as soon as possible.

If necessary, your GP or optometrist can refer you to an ophthalmologist (a specialist in diagnosing and treating eye conditions) for further assessment.

The ophthalmologist will check how well you are able to move your eyes. They may also use an instrument called an exophthalmometer to measure how far your eyeball protrudes.

If the ophthalmologist wants to examine your eye socket in more detail, a computerised tomography (CT) scan or magnetic resonance imaging (MRI) scan may be carried out.

You may also have a blood test to assess how well your thyroid gland is working, and you may be referred for an assessment by an endocrinologist (a specialist in conditions affecting glands and hormones) if you are found to have abnormal thyroid hormone levels.

Treating exophthalmos

If exophthalmos is being caused by thyroid eye disease, the following treatments are often helpful:

• medication to correct the level of thyroid hormones in your blood – this will not necessarily improve the problems with your eyes, but may stop them getting worse
• corticosteroid medication given directly into a vein (intravenously) – this can help reduce the inflammation associated with the condition
• corrective surgery – this may be carried out to improve the appearance of your eyes once the inflammation is under control

Other useful measures include stopping smoking, using artificial tears to reduce eye dryness and irritation, and wearing special lenses to correct double vision.

In other cases, treatment will vary depending on the underlying cause of the condition. For example, treatments such as radiotherapy, chemotherapy and/or surgery may be recommended if exophthalmos is caused by a tumour.

Read more about treating exophthalmos.

Outlook

The outlook for exophthalmos can vary considerably.

Many of the symptoms of thyroid eye disease tend to improve over time, although this can take a number of years, and there is a chance your eyes will continue to protrude if corrective surgery is not carried out.

Some people with exophthalmos are left with long-term vision problems, such as double vision, but permanent visual impairment is rare if the condition is identified and treated promptly.

If you have exophthalmos (bulging eyes), your eyes will need to be regularly examined.

This is because sometimes exophthalmos can get worse and so your eyes need to be closely monitored.

The treatment your ophthalmologist (eye specialist) recommends will depend on what is causing your symptoms.

Thyroid problems

If your exophthalmos is caused by a thyroid problem, treatment to improve the functioning of your thyroid gland may be recommended. The aim of treatment will be to return your thyroid hormone levels to normal.

For example, an overactive thyroid can be treated with medication, such as thionamides, that prevents your thyroid gland producing excess amounts of thyroid hormones.

Radioiodine treatment is another type of treatment for an overactive thyroid. It involves swallowing a chemical called radioactive iodine, which builds up in your thyroid gland and shrinks it.

Thyroid eye disease can sometimes get worse after radioiodine treatment. If radioiodine treatment is planned and you have thyroid eye disease, a careful assessment by an expert ophthalmologist or endocrinologist (a specialist in hormone conditions) will be required before going ahead.

Read more about treating an overactive thyroid gland.

Treating your thyroid problems will not necessarily improve your eye-related symptoms. However, an untreated overactive or underactive thyroid gland may make your eyes worse.

In general, the more severe your exophthalmos is and the longer you have had it, the more likely it is to become permanent. Therefore, you should seek medical advice as soon as you notice you have bulging eyes so that the underlying cause can be identified and appropriate treatment can be started as soon as possible.

Self-help 

Other things you can do to help treat eye-related symptoms of thyroid conditions include:

• raising the head of your bed – for example, by using extra pillows – which could help reduce some of the puffiness around your eyes 
• stopping smoking (if you smoke) because it can significantly increase the risk of your thyroid condition affecting your eyes (see below)
• wearing sunglasses if you have photophobia (sensitivity to light) 
• using eyedrops to help relieve soreness and to moisten your eyes if you have dry eyes  
• wearing a patch over one eye if you have double vision
• taking selenium supplements, which may help people with mild thyroid eye disease that has recently started (selenium is a mineral found in brazil nuts, meat and fish)

Smoking

The risk of developing thyroid eye disease is eight times higher in people who smoke than in people who do not smoke, or who have stopped smoking.

Non-smokers also tend to respond better to treatment for thyroid eye disease compared with people who smoke. However, this seems to reverse very quickly after a person gives up smoking.

Read more about giving up smoking.  

Corticosteroids

Corticosteroids are sometimes recommended to treat severe cases of thyroid eye disease, where the eyes are particularly painful and inflamed.

Corticosteroids contain manmade versions of the hormone cortisol, and are often used to reduce swelling and inflammation.

You may be prescribed a high dose of a corticosteroid called a glucocorticoid. This treatment is effective but can cause a number of side effects including:

• weight gain
• insomnia (difficulty sleeping)
• osteoporosis (fragile bones) 
• stomach ulcers 

You may be given corticosteroids intravenously (directly into a vein in your arm) because this method is thought to be safer and more effective than taking corticosteroid tablets.

Orbital radiotherapy

Radiotherapy is a treatment that uses high-energy radiation, usually X-rays, to destroy cells. Low doses of radiotherapy can be used on the eyes to help reduce the swelling. This is known as orbital radiotherapy.

Orbital radiotherapy may be considered if corticosteroids have not been effective, or if your condition is getting worse. It may also be combined with corticosteroids.

A review of a number of studies found that orbital radiotherapy was effective in treating eye symptoms caused by Graves’ disease, particularly when combined with corticosteroids.

Radiotherapy can cause some side effects, although these should be minimal if the treatment is carried out correctly.

Surgery

Depending on the underlying cause of your exophthalmos, surgery can be a very effective treatment. 

For example, surgery can be used if your exophthalmos is caused by a problem with the connection between the arteries and veins in your eyes.

Surgery is the only form of treatment that can improve severe exophthalmos in people with thyroid eye disease.

If you have other eye-related symptoms, surgery may be an option if these symptoms appear to be permanent and are not getting any worse.

For example, it may be possible to treat double vision by operating on your eye muscles to bring them back into alignment.

Surgery to your eyelids can move your lids so that you can completely close your eyes again.

Orbital decompression surgery

In severe cases of exophthalmos, such as where vision is affected, surgery may be required to remove the bony floors of your eye sockets (orbits). This procedure is known as orbital decompression surgery.

During this type of surgery, a small amount of bone will be removed from your eye sockets. Some of the fat surrounding the socket may also be removed. This allows any excess material that builds up, pushing your eyeballs forward, to move down into the space below. It also allows your eyes to sit further back in your head so that they do not protrude forward as much.

Possible complications that can occur following orbital decompression surgery include double vision, or it may make existing double vision worse. Ask your surgeon to explain the benefits and risks of the procedure to you.

The most common reason for performing orbital decompression surgery is to improve the appearance of people with thyroid eye disease who are affected by exophthalmos. However, surgery may also be required if your vision is at risk.

Treating a tumour

If you have a tumour behind your eye, your ophthalmologist will discuss with you the possibility of removing it.

Depending on the type of tumour you have, possible treatment options include:

• chemotherapy 
• radiotherapy 
• surgery, or
• a combination of these treatments