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Exophthalmos is not a condition. It is the Greek word used to describe bulging or protruding eyeballs. Proptosis is another term that also means bulging eyeballs.
Bulging eyeballs are usually a sign or symptom that you have a condition which is affecting the thyroid gland. The thyroid gland is located in the neck and controls the rate at which the body uses energy (metabolism).
When a thyroid condition causes symptoms that affect the eyes, it is known as a thyroid eye disease or thyroid orbitopathy. See Exophthalmos - symptoms for more information.
One condition that can cause thyroid eye disease and, therefore, exophthalmos is Graves’ disease. In rare cases, exophthalmos may be caused by other diseases. See Exophthalmos - causes for more information.
Graves’ disease is an autoimmune disease. This means that the immune system - the body’s natural defence system - attacks some of the body’s healthy cells and tissues. This usually causes the thyroid gland to become overactive (hyperthyroidism).
Graves’ disease can cause thyroid eye disease with symptoms that affect the eyes, such as:
Exophthalmos is a common symptom of thyroid eye disease, but thyroid eye disease can also exist without bulging of the eyes.
Nearly one-third of people with Graves’ disease develop thyroid eye disease and they commonly have exophthalmos.
How common is exophthalmos?
It is not clear exactly how common exophthalmos is. Each year there are an estimated five or six cases of thyroid eye disease for every 100,000 people. About two-thirds of people with thyroid eye disease have exophthalmos.
Thyroid eye disease is usually more common in women aged 30-50 years old. People who smoke also have a significantly increased risk of developing thyroid eye disease.
When exophthalmos is caused by thyroid eye disease, the eyes may not go back to normal. If the eyes are red, irritable and swollen, these symptoms usually settle down after a few months. However, in some cases it may take more than two years.
Treatment for the underlying thyroid problems will not necessarily help exophthalmos, but it is essential that the thyroid disease is treated. Corticosteroids are a type of medication that may reduce the swelling of your eyes, and radiotherapy (high-energy radiation) is also an effective treatment. In rare cases, surgery may be necessary. See Exophthalmos - treatment for more information.
The outcome of treatment can be excellent as long as treatment is carried out at centres with experience and expertise in dealing with this condition. The best results for people with thyroid eye disease come from treatment involving:
Exophthalmos means bulging or protruding eyeballs. The swelling of tissues behind the eyeballs pushes the eyes forwards, making them protrude from their sockets.
The eye sockets are made of rigid bone so cannot expand to accommodate the protruding eyeballs. The bulging tissues behind the eyeballs force the eyelids apart, causing you to take on a wide-eyed, staring expression. Most of the whites of your eyes may be exposed.
The eyelids also tend to become retracted or pulled back. This may cause a wide-eyed appearance without you having any bulging of the eyes.
Painful, dry and itchy eyes are also common symptoms associated with exophthalmos.
Limited eye movement
If you have exophthalmos, you may have limited eye movement. This is because the muscles that move your eyes are stiff, making it difficult to move your eyes. Muscle stiffness can result in double vision (diplopia).
Graves’ disease is a common cause of exophthalmos, which can also cause a number of other symptoms. A thyroid condition, such as Graves’ disease, that causes symptoms affecting the eyes is known as a thyroid eye disease. Other symptoms of thyroid eye disease include:
Symptoms of Graves’ disease that can affect the rest of your body include:
Other eye conditions
Sometimes, thyroid eye disease can be difficult to diagnose, especially in the early stages and when there is no exophthalmos. In these cases, treatment may be incorrectly given for another condition that affects the eyes, such as:
Factors that might suggest thyroid eye disease rather than any of these other conditions are:
Thyroid eye disease may affect your ability to drive. You are legally obliged to inform the Driver and Vehicle Licensing Agency (DVLA) about a medical condition that could have an impact on your driving ability.
Visit the Directgov website to find out how to tell the DVLA about a medical condition.
Thyroid problems are the most common cause of exophthalmos. They are often caused by Graves’ disease.
The thyroid gland
The thyroid gland is located in the neck, just below the Adam’s apple. It produces hormones that control the rate at which the body uses energy (metabolism). Thyroxine and triiodothyronine are the hormones produced by the thyroid gland.
Thyroid eye disease
A condition that affects the thyroid gland, such as an overactive thyroid (hyperthyroidism) or an underactive thyroid (hypothyroidism), can sometimes cause thyroid eye disease. This is also known as thyroid orbitopathy. In rare cases, thyroid eye disease can occur without any problems of the thyroid gland.
Thyroid eye disease affects the soft tissues and muscles that surround the eyes and increases the amount of fluid behind the eyeballs. The tissues around the eyes become swollen and inflamed. This results in the eyeballs being forced forward and out of the eye sockets, causing exophthalmos.
Graves’ disease is an autoimmune condition (see below) and is the most common cause of an overactive thyroid. It is estimated that up to 30% of people with Graves’ disease develop thyroid eye disease.
The immune system is the body’s natural defence against infection and illness. It releases white cells, antibodies and other chemicals to help fight infection and disease. In autoimmune conditions such as Graves’ disease, the body’s immune system turns against healthy cells and tissues. The exact reason for this is unknown.
If the autoimmune attack targets the thyroid gland, the thyroid gland may react by producing more thyroid hormones. The autoimmune attack can also involve soft tissues and muscles surrounding the eyes, causing eye problems, such as dry, ‘gritty’, swollen eyes and exophthalmos.
Exophthalmos does not always occur at the same time as thyroid gland problems, such as hyperthyroidism or hypothyroidism. It may occur months or years afterwards. Sometimes, exophthalmos can occur before thyroid problems develop and, in rare cases, the thyroid gland is not involved.
Exophthalmos is often caused by Graves’ disease which:
Exophthalmos is often recognisable from the appearance of the eyeballs, which bulge or protrude from the sockets, exposing most of the whites of the eyes.
Referral to an ophthalmologist
If your GP suspects that you have exophthalmos, they may refer you to an ophthalmologist, who can carry out further investigations to confirm the diagnosis. An ophthalmologist is a medical doctor who specialises in diagnosing and treating eye conditions. They mainly work in hospitals and hospital eye departments.
To help confirm exophthalmos, you may have a blood test or a thyroid function test to check whether your thyroid gland is functioning properly.
Your ophthalmologist will also carry out some tests to check your ability to move your eyes. They will also measure the degree of eyeball protrusion using an instrument called an exophthalmometer.
CT or MRI scan
A computerised tomography (CT) scan or magnetic resonance imaging (MRI) scan may be used to examine your eye socket in more detail.
During a CT scan, pictures of your body are taken and a computer is used to put them together to form a detailed image. An MRI scan is a similar technique that uses a strong magnetic field and radio waves to produce a detailed image of the inside of your body.
A CT or MRI scan can highlight any abnormalities that may be present in or around your eyes, such as a tumour (growth).
If you are diagnosed with exophthalmos, your ophthalmologist (eye specialist) will want to examine your eyes regularly. This is because, in some people, exophthalmos can get worse and the functioning of your eyes needs to be monitored.
If you have exophthalmos, the treatment your ophthalmologist recommends will depend on what is causing your symptoms.
If your exophthalmos is caused by a thyroid problem, treatment to improve the functioning of your thyroid gland may be recommended. The aim of this type of treatment will be to return your thyroid hormone levels to normal.
For example, an overactive thyroid can be treated with thionamides, a type of medication that prevents your thyroid gland producing excess amounts of thyroid hormones. See the A-Z topic about Overactive thyroid - treatment for more information.
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) is required before going ahead.
Treating your thyroid problems will not necessarily improve your eye symptoms. However, an untreated overactive thyroid or an untreated underactive thyroid can make the eyes worse.
In general, the longer you have had exophthalmos and the more severe it is, the more likely it is to be permanent. It is important to seek medical advice as soon as you notice exophthalmos so treatment can be started immediately.
Some other treatments that can be used to treat the eye symptoms of thyroid conditions include:
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 quit smoking. The response of people who smoke to treatment for thyroid eye disease is also worse than for people who do not smoke, although this seems to reverse very quickly once you stop smoking.
If you smoke, you are also less likely to have your overactive thyroid cured after a course of treatment with thionamide medicine than people who do not smoke.
See the A-Z topic about Quitting smoking for further information and advice about giving up smoking.
Corticosteroids may be recommended to treat severe cases of thyroid eye disease where the eyes are particularly painful and inflamed. Corticosteroids are often used to reduce swelling and inflammation.
You may be prescribed a high dose of a type of corticosteroid called a glucocorticoid. This treatment is effective but can cause a number of side effects such as:
You may be given corticosteroids intravenously (directly into a vein in your arm) as this is thought to be safer and more effective than taking corticosteroid tablets.
See the A-Z topic about Corticosteroids for more information.
Radiotherapy is a type of treatment that uses controlled doses of high-energy radiation, usually X-rays, to destroy cells. Low doses of radiotherapy can be used on the eyes to reduce the swelling. This is called orbital radiotherapy.
Orbital radiotherapy may be considered first, or if corticosteroids alone have not been effective or if your condition is getting worse. It may 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. See the A-Z topic about Radiotherapy for more information.
In some cases of exophthalmos, surgery is a very effective treatment. It will depend on the underlying cause of your exophthalmos. For example, surgery may be required if you have exophthalmos that is caused by a problem with the connection between the arteries and veins in your eyes.
Surgery is the only treatment that can improve significant exophthalmos in people with thyroid eye disease.
If you have other eye symptoms, surgery may be an option if these symptoms appear to be permanent and are not getting any worse. For example:
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 orbital decompression surgery, a small amount of bone is 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.
Complications can occur following surgery, for example the operation may cause 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. Surgery may also be required when your vision is at risk. Centres with experience in this type of surgery have excellent results.
Treating a tumour
If you have a tumour behind your eye, your ophthalmologist will discuss the possibility of removing it with you. Depending on the type of tumour you have, possible treatment options include:
Corneal damage and conjunctivitis
If you have particularly severe exophthalmos or proptosis, you may be unable to close your eyes properly.
This can damage your cornea (the transparent tissue that covers the front of your eyeball) by causing it to dry out. If your cornea becomes very dry, it may cause an infection or ulcers (open sores) to develop, which may damage your vision.
Conjunctivitis - inflammation of the lining of your eye - is another possible complication of exophthalmos or proptosis.
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