Thyroid eye disease causes the muscles and soft tissues within the eye socket to swell. This pushes the eyeball forward and causes various eye symptoms. Treatment involves steps to protect the eye as the disease runs its course. This may involve artificial tears, medicines and, in some cases, surgery. Thyroid eye disease is usually associated with an abnormality of thyroid gland function. This also needs to be treated.
What is thyroid eye disease?
Thyroid eye disease (TED) is a disease marked by swelling of the muscles and fatty tissues surrounding the eyeball within the eye socket (orbit).
The swelling is due to inflammation of these tissues. There is limited space inside the orbit so, as the tissues swell, the eyeball is pushed forward. This causes the clear window in the front part of the eye (the cornea) to lose its protection, which is provided by the eyelids. The eyeball cannot move so easily as the muscles that control it work less well. When the disease is very severe, the nerve connecting the eyeball to the brain can be compressed and damaged. This period of swelling is followed by a healing response.
TED is sometimes called other names such as thyroid ophthalmopathy, dysthyroid eye disease, Graves' ophthalmopathy or ophthalmic Graves' disease.
Understanding thyroid eye disease
The thyroid gland
The thyroid gland is a small butterfly-shaped gland sitting near the top of your windpipe (trachea) at the front of your neck. It has an important role in controlling the speed at which chemical reactions happen in the tissues throughout your body (metabolic rate). The thyroid gland can become overactive or underactive. This is most often due to an autoimmune disease.
The immune system normally makes small proteins (antibodies) to attack germs (bacteria, viruses and other microbes). In people with autoimmune diseases, the immune system makes antibodies against tissues of the body. It is not clear why this happens. Some people have a tendency to develop autoimmune diseases. In such people, something might trigger the immune system to attack the body's own tissues.
Thyroid eye disease
Autoimmune thyroid disease occurs when the body's antibodies attack the thyroid gland. In some people, these same antibodies also attack the tissues surrounding the eyeball. This is TED. It is not known exactly why this happens in some people and not in others. So, TED is an autoimmune disease, most often occurring in association with an overactive thyroid gland. Occasionally, TED occurs when the thyroid gland appears to be working normally. However, people with an apparently normal thyroid gland at the time of TED have usually had abnormal thyroid function in the past or they go on to develop abnormal thyroid function in the future.
Who gets thyroid eye disease?
This is a rare condition affecting about 16 women in every 100,000 people and 3 men in every 100,000 people each year. Most of these people have a problem with an overactive thyroid gland and have an underlying autoimmune condition. It generally occurs in middle age. Some people carry genes that makes it more likely that they will get thyroid eye disease. It is also more likely to develop if you smoke.
What are the symptoms of thyroid eye disease?
Symptoms are caused by the tissues of the eye socket swelling and pushing the eyeball forward:
- The front of your eyes can get red and irritated as the sensitive cornea is less well covered or lubricated by the eyelids.
- The front of your eyes may feel (and be) dry if the tear-producing gland (the lacrimal gland) has been affected.
- Your eyes may ache.
- Your eyes may look more bulgy, giving you a staring appearance.
- You may get double vision (diplopia) as the muscles become too swollen to work properly.
- In advanced disease, your vision may become blurred and colours can appear less vivid.
The two eyeballs are not always equally affected. You may have other non-eye symptoms due to the abnormal thyroid gland.
How is thyroid eye disease diagnosed?
Diagnosis can be made simply on examining your eyes if you already have a diagnosis of a thyroid gland problem.
Sometimes, blood tests are needed to back up the diagnosis. They look at how well the thyroid gland is functioning by measuring its chemical messengers (hormones) in your bloodstream. These are called thyroid function tests (TFTs). More specialised blood tests can be done to measure the antibodies in your blood.
Occasionally, thyroid scans need to be done to see how actively the thyroid gland is working (uptake scans). If the doctors are particularly concerned about the swelling in the orbit, they may organise a scan (known as an MRI) which will show up which tissues have been most affected.
Doctors will want to assess your general sight carefully, including how well you see colours and how good the vision out of the corner of your eye (your peripheral vision) is. They may also want to carry out an eye movement test to see how much the muscles have been affected. These assessments will be repeated throughout the course of the disease.
What is the treatment for thyroid eye disease?
This is a self-limiting disease: if left untreated, the inflammation will gradually go by itself. But, the symptoms caused by the swelling (such as bulging eyes) may remain, as some of the tissues that have been stretched may not always be able to return to their original form. The aim of treatment is mainly to limit damage occurring during the inflamed period. There are also treatments for people whose tissues have not been able to return to their original form after the inflammation has settled. The eye problems will be managed by an eye doctor (ophthalmologist) and the underlying thyroid problem by your own doctor or by a a specialist in the hormone systems of the body (an endocrinologist).
- In the early phase of the disease and where the disease stays mild, artificial tears (ocular lubricants) may be enough.
- As the disease progresses, you may need immunosuppressive drugs - a family of medicines that dampens down the immune system which is producing these abnormal antibodies.
- Commonly used immunosuppressants are steroids such as prednisolone. You will be given some other medicines to counteract some of the more common side-effects of steroids such as omeprazole, a medicine that protects the lining of the stomach.
- If you have very severe disease and the doctors are concerned about your sight, you may be admitted into hospital for a course of steroids administered through a drip.
- About 5 in 100 people with TED have such severe disease that the optic nerve (connecting the back of the eyeball to the brain) is compressed. This can permanently damage your vision. If this is the case, the doctor may decide to organise decompression surgery. This is a procedure that creates a space within the orbit for the inflamed tissues to spread into. This relieves the pressure on the nerve.
- Some people find that once the inflammation has settled, they are left with unacceptably bulgy eyes. Surgery can be done on the orbit in some cases to allow the eyeballs to settle back into the sockets.
- Occasionally, surgery to the stretched muscles or to the lids is needed to get everything back into place.
- If there are problems with stretched tissues that need surgical correction once the inflammation has settled, surgery is done to the orbit first, then to the muscles and then to the lids.
Other types of treatment
If you develop double vision (diplopia), you may be referred to a specialist health professional who manages problems with eye muscles (an orthoptist). They may give you modified glasses that block off vision from one eye (like a patch) or put a special cover, called a prism, over one side to stop the diplopia.
Radiotherapy (treatment by exposure to a radioactive substance) may be used in some places on some people. The aim is to reduce the swelling in the eye. It is used alongside other forms of treatment.
There are a number of new treatments that are being investigated. They are still in the pipeline but a lot of work is being done to improve the options for people with TED.
Additionally, your doctors will treat any abnormality of thyroid function. This is usually with tablets but may also include radioactive iodine or, uncommonly, surgery to the thyroid gland.
Is there anything I can do?
Yes. Here are a few tips:
- We know that one thing that makes this disease worse is smoking. If you do smoke, see your GP about getting help to stop.
- Sleeping propped up will help reduce the puffiness (congestion) around the eyes.
- You may find bright light uncomfortable. Sunglasses will help.
- If you are a driver, let the DVLA know if you experience double vision. This is a legal requirement. Usually, they will contact your ophthalmologist for a report. If the double vision is well controlled with prisms, you may be declared fit to drive.
Are there any complications from thyroid eye disease?
Most people do not develop permanent complications. However, they do occur in some people, especially those where treatment is delayed or where the TED has been severe. They are also more likely in older people, in those who smoke and in people with diabetes. Possible complications include:
Complications from the disease
- Damage to the clear window of the eye (the cornea).
- Permanent squint or double vision.
- Damage to the nerve of the eye, resulting in poor vision or colour appreciation.
- Unsightly appearance.
Complications from treatment
- Side-effects from the immunosuppressive medicines.
- Side-effects from the surgery:
- New double vision (about 15 in 100 people with TED).
- Loss of vision (less than 1 in 1,000 people with TED).
- There are some other very rare complications that your surgeon will talk you through.
What is the outlook (prognosis) for thyroid eye disease?
This is a drawn-out illness. The inflamed period tends to last months to years (usually about two years). However, for most people it will be a mild disease needing lubricants and regular assessments only. It 'burns out' (fades away) by itself. For those with more severe disease, the outlook depends on how early it is diagnosed and how intensive the treatment is. About 1 in 4 people will end up with reduced eyesight.
Further help & information
Dr Tim Kenny
Dr Laurence Knott
Prof Cathy Jackson