Alternative names for thyroid eye disease
TED; Graves’ ophthalmopathy; Graves’ orbitopathy; Graves’ eye disease; thyroid ophthalmopathy; TO; thyroid associated ophthalmopathy; thyroid associated orbitopathy.
What is thyroid eye disease?
Thyroid eye disease is an autoimmune condition affecting the eyes that is associated with Graves’ disease. Graves’ disease is an autoimmune thyroid condition where the body’s immune system produces auto-antibodies that activate receptors in the thyroid gland causing it to produce too much thyroid hormone (hyperthyroidism). This immune response against the thyroid gland can sometimes also affect the eyes – as in thyroid eye disease.
What causes thyroid eye disease?
The exact cause of thyroid eye disease is not known but it is thought to be caused by an abnormal immune response which is targeted at the healthy tissues of the eye. This leads to the eyes becoming sore, watery, swollen and red. This inflammation is directed against several different parts of the eyes, including the muscle and fat behind the eyes. This results in the eyes becoming prominent or giving an appearance of a permanent stare. Similar inflammation of the muscles that move the eye can result in the muscles becoming stiff. As a result, the eyes do not move together, causing double vision. In severe cases of stiffness, squinting may result.
What are the signs and symptoms of thyroid eye disease?
Early symptoms of thyroid eye disease are itching, watering or dry eyes and a feeling of grittiness of the eyes. Some people may notice a swelling around the eyelids and sometimes the front of the eye becomes swollen. The eyelids may become uneven in size and they may seem to sit further back on the eyeballs (known as retraction of the eyelids). Patients may experience prominent or protruding eyes (like a stare), and in more advanced cases, double vision.
Rarely, patients may not be able to completely close their eyes due to protrusion of the eyeball. This exposes the cornea (membrane that covers the eyeball) to damage from dirt, causing reduced vision. Sometimes the swelling at the back of the eyes can press on the nerve behind the eye (optic nerve) causing pain, ‘washed out’ colour vision and reduced vision which, if untreated, can lead to blindness.
How common is thyroid eye disease?
About one in four patients with Graves’ disease will have thyroid eye disease. It does not occur with other causes of an overactive thyroid (such as a toxic thyroid nodule).
Thyroid eye disease is almost five times more common in women than men. However, the disease is often more severe in men. In 90% of people it is associated with an overactive gland, in which case it may be diagnosed before, after, or at the time of diagnosis of Graves’ disease. In 5% of people it is associated with an underactive thyroid gland and 5% of people affected do not have any thyroid problems. Thyroid eye disease is seven times more likely to occur in smokers.
Is thyroid eye disease inherited?
No, thyroid eye disease is not inherited. However, autoimmune conditions tend to run in families, and it is likely that a patient with thyroid eye disease may have some other autoimmune disease.
How is thyroid eye disease diagnosed?
Thyroid eye disease is often diagnosed at the same time as Graves’ disease. The signs and symptoms described above such as red, swollen eyes will prompt the doctor to suspect thyroid eye disease. A simple blood test called a thyroid function test will be carried out to measure the levels of thyroid hormones (thyroxine and triiodothyronine) and thyroid stimulating hormone in the bloodstream. In Graves’ disease, levels of thyroxine and/or triiodothyronine will usually be raised with undetectable levels of thyroid stimulating hormone. Blood tests may also be carried out to detect thyroid antibodies, which would indicate autoimmune thyroid disease.
If the signs and symptoms are doubtful (for instance, if only one eye is affected), a computerised tomography (CT) or magnetic resonance imaging (MRI) scan of the eyes may be used to examine any swelling of the tissues behind the eye.
How is thyroid eye disease treated?
It is important to keep the thyroid function stable. The treatment will depend on whether the thyroid gland is overactive (majority of cases) or underactive. An overactive gland is treated with antithyroid tablets such as carbimazole or propylthiouracil to treat the raised hormone levels. These act on enzymes in the thyroid gland to prevent production of thyroid hormones. A block and replace regime should be used where a high dose of the drug stops the thyroid gland working altogether and this is combined with replacement doses of thyroid hormone. In the case of an underactive gland, thyroxine replacement tablets will need to be taken daily for life (see the article on hypothyroidism for more information).
Smoking is the biggest external factor known to make the disease worse and it is important for affected people to stop smoking immediately.
Symptoms of thyroid eye disease should be treated as they happen. These can include:
Dry eyes – Use of artificial liquid tears can help
Eyes not closing at night – Ointment, eye pads and taping the eyelids closed can help to keep the eye moist and protected
Swelling around the eyes – Raising the head further at night with the help of extra pillows or raising the head end of the bed may help
Double vision – use of special glasses with prisms can help; after the disease has settled down, eye muscle surgery can correct residual double vision
Deteriorating vision or worsening prominence – medications such as steroids or steroid-like medications (immunosuppressive treatment) are used to reduce the swelling. They are usually used at a high dose to start with and continued for a long time. Radiotherapy to the tissues behind the eyes is also effective but takes several months to work.
It may be important to continue these treatments until the inflammation dies down, which generally takes 12 to 18 months. The extent of the residual effects of the disease can then be assessed. Following significant thyroid eye disease, rehabilitative surgery is frequently required to return the eyes to their previous appearance and function. A series of different operations including operating on the eyelids, eye muscles or orbital decompression to reduce the pressure behind the eyes, may be needed. If there is any risk to vision, decompression by surgery may need to be carried out urgently.
Are there any side-effects to the treatment?
Long-term treatment with steroids used in severe cases of thyroid eye disease (if the vision is deteriorating) can cause side-effects such as weight gain and diabetes.
Surgery for cosmetic reasons should be carried out after the inflammation has died down in order to avoid repeated operations. There are general risks associated with surgery and anaesthesia which should be reviewed by the surgeon or anaesthetist.
Antithyroid tablets can very rarely suppress the production of white blood cells, making the individual more open to infections. Anyone who experiences a sore throat, mouth ulcers or a high temperature whilst taking the tablets should seek medical attention immediately.
Radioiodine therapy used to treat an overactive thyroid gland can worsen thyroid eye disease so this should be avoided while the eyes are inflamed. Radioiodine is therefore only used in mild eye disease if felt necessary and is usually combined with steroid treatment to minimise the risk. Patients should discuss any concerns with their doctor.
What are the longer-term implications of thyroid eye disease?
With the correct treatment, thyroid eye disease can be well managed and patients can live full and active lives. Most of the effects of the thyroid eye disease will settle with time and when thyroid function is stabilised. Patients taking carbimazole tablets to treat hyperthyroidism may need to take them daily for life. Regular blood tests should be carried out to monitor thyroid hormone levels and the dose of carbimazole adjusted accordingly. However, there are other treatment options such as thyroidectomy or radioiodine treatment which can be considered once the eye disease has settled down.
The changes in the physical appearance of the eyes can have a psychological effect on the individual, causing low self-esteem. The long-term consequences of the disease, even after the thyroid has settled down, may be difficult to accept. Some patients may have a permanent change to their appearance, which may require surgery. Very rarely, there is a permanent loss of vision – this can happen if the disease is left untreated at the sight-threatening stage.
Patients should stop smoking as this is known to aggravate the condition. Sunglasses may be necessary even when indoors. If double vision is not corrected, driving will be dangerous. If a patient has any concerns they should discuss them with their doctor.
Written: November 2011