Exophthalmos

Exophthalmos’ is a Greek word which means bulging or protruding eyeballs. Exophthalmos is not a condition in itself, but it can be caused by a number of different conditions which usually affect the thyroid gland. The thyroid gland is located in the neck and controls the body’s metabolism (the rate at which the body uses energy).

Grave’s disease

Grave's disease is the most common cause of exophthalmos. It is an autoimmune disease, which means that it causes the immune system to attack some of the body’s healthy cells and tissues. This often causes the thyroid gland to become overactive (hyperthyroidism).

Proptosis

Exophthalmos usually affects both eyes. However, sometimes only one eye protrudes, which is known as proptosis. Proptosis refers to the protrusion of any organ in the body.

Thyroid problems are the most common cause of exophthalmos. In particular, Grave’s disease – an autoimmune disease that causes the thyroid gland to produce an excess amount of thyroid hormone (hperthyroidism) – is often associated with exophthalmos.

In exophthalmos, an increase in the amount of white cells (lymphocytes) in the eye, plus the inflammation and swelling that occurs as a result of an excess amount of thyroid hormone, results in the eyeballs being forced forward out of the eye sockets (orbits).

The thyroid gland

The thyroid gland is located in the neck, just below the Adam’s apple. It is one of the body’s endocrine glands which produce hormones (chemicals) that control the body’s metabolism (the rate at which the body uses energy). Thyroxine and triiodothyronine are the thyroid hormones that are produced by the thyroid gland.

Thyroid eye disease

Thyroid eye disease – sometimes known as thyroid orbitopathy (TO) – is a condition that affects the soft tissues and muscles that surround the eyes. The tissues of the eyes become swollen and inflamed. Thyroid eye disease is usually associated with an over-active thyroid gland (hyperthyroidism) or, sometimes, an under-active thyroid gland (hypothyroidism).

Autoimmune diseases

The immune system is the body’s natural defence system. It releases antibodies to help fight off infection and disease. However, an autoimmune disease, such as Grave’s disease, causes the immune system to produce auto-immune antibodies which attack healthy cells and tissue. The exact reason why this occurs is unknown.

If the auto-immune antibodies attack the thyroid gland, the thyroid gland will react by producing more thyroid hormones. The autoimmune antibodies and excess thyroid hormone can attack the soft tissues and muscles surrounding the eyes, causing eye problems such as:

  • dry, ‘gritty’ eyes,
  • redness,
  • puffiness,
  • swelling and inflammation,
  • vision problems, and
  • bulging eyeballs (exophthalmos).

Hereditary diseases

As autoimmune diseases, such as Grave's disease, are hereditary, exophthalmos may also run in families.

Exophthalmos does not always occur at the same time that thyroid gland problems, such as hyperthyroidism, or hypothyroidism, occur. It may occur months or, sometimes, years afterwards. However, sometimes, exophthalmos can occur before thyroid problems develop.

Proptosis

Proptosis (protrusion of one eyeball) may be caused by the presence of other material in the eye socket, such as:

  • a cancer,
  • a mucus-filled cyst (mucocoele),
  • a brain tumour, or
  • a blood clot.

Proptosis may also develop as a result of an injury (trauma) to the eye, or an infection in the sinuses.

If you notice that one, or both, of your eyeballs are protruding, you should seek medical advice immediately. It is important to remember that in many cases tumours are benign.

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 exophthalmos, they may refer you to an ophthalmologist (eye specialist) who will be able to carry out further investigations in order to confirm the diagnosis.

In order to help confirm exophthalmos, you may have a blood test, or a thyroid function test, to check whether your thyroid gland is functioning properly.

The ophthalmologist may also carry out some tests to check your ability to move your eyes, and to measure the degree of eyeball protrusion using an instrument called an exophthalmometer. If you have exophthalmos, you will be able to look upwards without moving your eyebrows.

CT or MRI scan

A computerised tomography (CT) scan, or a magnetic resonance imaging (MRI) scan, may be used to examine your eye socket (orbit).

During a CT scan, pictures of the body are taken and a computer is used to put them together to form a detailed image. An MRI scan is a similar diagnostic 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 will be able to highlight any abnormalities that may be present in or around your eye, such as a tumour.

Bulging, or protruding, eyeballs are the most obvious and noticeable symptom of exophthalmos.

In thyroid conditions, such as Grave’s disease, bulging eyes occur as a result of the swelling of tissues in the eyeballs, and an increase in the number of cells in the eye. This pushes the eyes forward, making them protrude from their sockets (orbits).

As the eye sockets are made of rigid bone, they are unable to expand in order to accommodate the protruding eyeballs. The bulging eyeball forces the eyelid apart, causing you to take on a ‘wide-eyed’, staring expression. In exophthalmos, most of the whites of the eyes are exposed.

Grave’s disease

The symptoms of Grave’s disease that affect the eyes include:

  • painful eyes,
  • dry eyes,
  • irritation of the eyes,
  • photophobia (sensitivity to light),
  • the production, secretion, and shedding of tears (lacrimation),
  • weakness of the eye muscles which causes double vision (diplopia), and
  • vision loss that is caused by compression of the optic nerve.

Symptoms of Grave’s disease that can affect the body as a whole include:

  • palpitations (irregular heart beats),
  • anxiety,
  • increased appetite,
  • weight loss, and
  • insomnia (difficulty sleeping).

If you have Grave's disease, it may have implications for driving. See the 'useful links' section for how to inform the DVLA about medical conditons.

Limited eye movement

If you have exophthalmos, you may have limited eye movement. This is because the muscles in your eyes are weakened making it difficult to move your eyes. Muscle weakness can also result in the eyes turning inwards (amblyopia), or it can cause double vision (diplopia).

Painful, dry, and itchy eyes are also common symptoms that are associated with exophthalmos.

If your child has a bulging eye, you should take them to see your GP. It may be due to a sinus infection.

                             

If you are diagnosed with exophthalmos, your opthalmologist will want to examine your eyes on a regular basis. This is because exophthalmos is a progressive disease and your symptoms will worsen over time.

If you have exophthalmos, the treatment that your ophthalmologist will recommended for you will depend on what is causing the symptom.

Thyroid problems

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

After treatment has been started, the appearance of your eyes and any distortion to your vision will hopefully be restored to normal. However, in some cases of exophthalmos, such as those that are caused by Grave’s disease, thyroid treatment may not help to improve bulging eyes and, sometimes, changes to your vision and the appearance of your eyes may be long-term or permanent.

Therefore, it is important that you seek medical advice as soon as you notice exophthalmos, so that treatment can be started immediately.

Surgery

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.

In very severe cases of exophthalmos, surgery may also be required to remove the bony floors of your eye sockets. This procedure is known as surgical orbital decompression. It allows the build up of any excess material, such as the white cells (lymphocytes) that are pushing your eyeballs forward, to move down into the space below. This space is known as the maxillary sinus (antrum).

Other treatments

As well as surgery and thyroid treatments, there are a number of other treatments that can be used to help improve the symptoms of exophthalmos.

Eye drops and eyeshades

For dry eyes, lubrication of the cornea (the transparent tissue that covers the front of your eyeball) using eye drops will help keep your eyeballs moist. If your eyes are painful and sensitive to light (photophobia), wearing eyeshades may help.

Corticosteroids

In severe cases of exophthalmos, where your eyes are particularly painful and inflamed, corticosteroids may be recommended. Corticosteroids are a type of medication that is often used to reduce swelling and inflammation.

Therefore, if you are prescribed a course of corticosteroids, it should help to improve your symptoms by reducing the inflammation in your eyes.

Treating a tumour

If you have a tumour behind your eye, your opthalmologist will discuss with you the possibility of removing it. Depending on the type of tumour that you have, chemotherapy, radiation therapy, surgery, or a combination of these, are all possible treatment options.