Wednesday, July 18, 2012

What Is Exophthalmos? What Causes Exophthalmos?

Exophthalmos, or exophthalmia, is a protruding eyeball anteriorly out of the orbit (eye socket). The Greek word ophthalmos means "eye" and the Greek word ex means "out". Exophthalmos can be either bilateral (both eyes bulge out) or unilateral (just one eye bulges out). Doctors use an exophthalmometer to measure the degree of exophthalmos.

Depending on the severity of the exophthalmos, if it is left untreated the eye lids may fail to close during sleep, resulting in corneal dryness and eventual damage. People with exophthalmos also risk developing superior limbic keratoconjunctivitis, where the area above the cornea becomes inflamed because of the friction that occurs when the patient blinks. Some patients may experience compression of the optic nerve or ophthalmic artery, which can eventually affect the patient's eyesight, leading to blindness.

Exophthalmos is not a condition, but rather a sign of a condition, usually caused by something wrong with the thyroid gland.

According to Medilexicon's medical dictionary, exophthalmos is "Protrusion of one or both eyeballs; can be congenital and familial, or due to pathology, such as a retroorbital tumor (usually unilateral) or thyroid disease (usually bilateral)."

What are the signs and symptoms of exophthalmos?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor notice. For example, pain may be a symptoms while a rash may be a sign.

The most noticeable sign of exophthalmos are bulging or protruding eyeballs (either one or both). If the patient has Graves' disease, a thyroid condition, the bulging develops because the tissues in the eyeballs swell, and the number of cells in the eye increases - resulting in larger eyes which push forward from their orbits (sockets). The human eye sockets are rigid and cannot expand to accommodate the larger eyeball. As the eyeball protrudes the eyelid is forced apart, giving the patient a staring expression with a higher-than normal proportion of the whites of the eyes exposed.

Graves' disease is the most common cause of bulging eyeballs. Signs and symptoms of Graves' disease include:
  • Pain in the eyes
  • Dry eyes
  • Eye irritation
  • Sensitivity to light (photophobia)
  • Lacrimation - eye secretions and shedding of tears
  • Diplopia - double vision caused by the weakening of the eye muscles
  • Progressive blindness, if the optic nerve is compressed
  • Difficulty in moving eyes - as the eye muscles weaken the patient may find it harder to move the eyes. In some cases the eyes may turn inwards (amblyopia).
The following non-ocular signs and symptoms are also possible with Graves' disease:
  • Irregular heartbeats (arrhythmia, palpitations)
  • Anxiety
  • Raised appetite
  • Sleeping problems (insomnia)

What are the causes of exophthalmos?

Graves' disease, an autoimmune disease that causes hyperthyroidism (thyroid gland produces too much thyroid hormone) is the most common cause of exophthalmos. Thyroid problems generally are common causes.

The thyroid gland - the thyroid gland is in the neck, below the Adam's apple. It produces hormones which help to regulate growth and the rate of chemical reactions (metabolism) by which the body uses energy. The thyroid gland produces thyroxine and triiodothyronine.

Thyroid eye disease - also known as TO (thyroid orbitopathy), is a condition in which the soft tissues and muscles surrounding the eyes become swollen and inflamed. This condition is closely linked to hyperthyroidism (overactive thyroid gland), and sometimes hypothyroidism (underactive thyroid gland).

Exophthalmos does not necessarily occur during the onset of hyperthyroidism or hypothyroidism. The eyes may start bulging long after a thyroid problem starts; and even before.

Autoimmune diseases - healthy people's immune systems attack pathogens; organisms and substances that are bad for us, such as some bacteria, viruses, parasites, cancer cells and fungi. If the person's immune system starts attacking good tissue they have an autoimmune disease - the immune system is attacking parts of the person's body that are needed for good health. Graves' disease is an example of an autoimmune disease. Experts are not sure why autoimmune diseases, such as Graves' disease occur.

If the patient's immune system attacks the thyroid gland it often reacts by producing more hormones than normal. The excess thyroid hormone, as well as the autoimmune antibodies may attack the muscles and soft tissue surrounding the eyes, causing:
  • Dry eyes (often described as gritty eyes)
  • Redness
  • Puffy eyes
  • Inflammation and swelling
  • Problems with eyesight
  • Exophthalmos (bulging or protruding eyes)
Inherited diseases - some diseases which may affect the eyes are inherited, the patient has acquired the faulty genes from their parents or grandparents. Graves' disease is an example of a hereditary disease.

Proptosis (eyeball protrusion, one eye) - the presence of something in the eye-socket can cause proptosis, such as:
  • A cancerous tumor
  • Mucocoele (mucus-filled cyst)
  • A blood clot
  • Trauma (eye injury)
  • Sinus infection
Anybody who notices that one or both eyes are starting to bulge should see their doctor immediately.

How is exophthalmos diagnosed?

In most cases the protrusion or bulging of the eyeballs from the sockets, with much more of the whites of the eyes exposed, is enough for the doctor to diagnose exophthalmos fairly easily. However, as mentioned earlier, exophthalmos is a sign of some disease or condition, and is not a disease in itself. Therefore, if a GP (general practitioner, primary care physician) suspects exophthalmos the patient will probably be referred to an eye specialist - an ophthalmologist. The ophthalmologist will most likely order further tests before confirming a diagnosis.

The following tests may be ordered:

A blood test - this will probably be a thyroid function test to see whether the thyroid gland is healthy.

Exophthalmometer - this instrument measures the degree of eyeball protrusion as well as determining how well the patient can move their eyes. Patients with exophthalmos will be able to look upwards without moving their eyebrows.

Imaging scans - in order to examine the orbit (socket) the doctor may order a CT (computerized tomography) scan or an MRI (magnetic resonance imaging) scan. A scan may also detect a tumor, or any abnormalities in or around the eyes.

What are the treatment options for exophthalmos?

As exophthalmos tends to be a progressive disease - symptoms get worse over time - the ophthalmologist will wish to monitor the patient regularly. Treatment depends on several factors, including the cause, as well as the patient's age and general health.

Thyroid problems - the doctor will treat whatever is causing the thyroid problem so that thyroid hormone levels are brought back to normal. Usually, effective thyroid treatment results in the restoration of normal vision and the appearance of the eyes.

If the patient has Graves' disease thyroid treatment might make no difference to the appearance of the eyes. On occasions the affected vision and appearance of the eyes cannot be improved.

It is important to see your doctor as soon as you notice any bulging of the eyes. Treatment is much more effective if it can begin early.

Surgery - if there is a problem with the connection between the arteries and veins in the eyes the patient may have to undergo surgery. In severe cases the bony floors of the eye sockets may have to be surgically removed (surgical orbital decompression). The procedure allows excess material to move down into the extra space in the antrum (maxillary sinus) by the surgical intervention.

Eye drops - if the patient suffers from dry eyes, eye drops will help keep the eyeballs moist - it is important to keep the cornea lubricated.

Eyeshades - eyeshades may be required if the patient suffers from photophobia (oversensitivity to light).

Corticosteroids - for patients whose eyes are especially painful or swollen (inflamed), the doctor may prescribe corticosteroids. Corticosteroids are effective in reducing swelling and inflammation.

A tumor - most likely the doctor will talk to the patient about removing the tumor surgically, as well as using chemotherapy, radiotherapy (radiation therapy), or a combination.

What are the possible complications of exophthalmos?

In severe cases patients may not be able to close their eyes properly, especially when they are asleep. This can cause the cornea to dry out and become damaged. If the cornea dries out too much there is a much higher risk of infection or ulcers, which can damage vision.

People with exophthalmos or proptosis are more susceptible to developing conjunctivitis.

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