Exophthalmos describes a condition where the eyeball protrudes from the eye socket, making it appear to bulge. It can affect one or both eyes.
In the long-term, symptoms tend to improve, but this can take years. There is a possibility that the eyes may continue to bulge if treatment is not received.
Exophthalmos is not a condition, but the sign of a disorder. Commonly, it can signal a problem with the thyroid gland. Graves' disease is the most common cause of exophthalmos.
The thyroid is in the neck, below the Adam's apple. The hormones it produces help to regulate growth, the rate of metabolism and other important functions of the body. The hormones are called thyroxine and triiodothyronine, and they are normally kept in balance.
Thyroid eye disease is a condition where the soft tissues and muscles around the eyes become swollen and inflamed.
It is often due to hyperthyroidism, and sometimes to hypothyroidism, which is caused by an underactive thyroid gland.
Hyperthyroidism or hypothyroidism may not cause the eyes to protrude immediately. It may take some time for this to happen.
In a healthy person, the immune system attacks pathogens, the organisms and substances that are bad for us. These include some bacteria, viruses, parasites, cancer cells, and fungi. However, in certain people, the immune system starts attacking normal tissue. This is described as an autoimmune reaction.
Graves' disease is an example of such an autoimmune reaction. Experts are not sure why autoimmune diseases occur. If a person's immune system attacks the thyroid gland, it may react by producing extra hormones.
The autoimmune antibodies can attack the muscles and soft tissue surrounding the eyes, which can cause them to protrude from the sockets.
This can lead to:
- dry or gritty eyes
- puffy eyes
- inflammation and swelling
- vision problems
Graves' disease is the most common cause of exophthalmos. Anywhere from 25-50 percent of people with this condition will have an eye involvement.
Interestingly, eye involvement can occur up to 10 years before the diagnosis of thyroid problems is made and up to 20 years after. The immune cells that attack the thyroid in Graves' disease also accumulate within the eye socket. The fatty tissue and muscles around the eye become large, pushing the eye forward and out.
A person who has Graves' exophthalmos may experience the following symptoms:
- pain in the eyes
- dry eyes
- eye irritation
- photophobia, or sensitivity to light
- lacrimation, or eye secretions, and shedding of tears
- diplopia, or double vision caused by weakening of the eye muscles
- blurred vision
- blindness if the optic nerve is compressed
- difficulty in moving eyes, as the eye muscles are affected
- feeling pressure behind and around the eyes
While Graves' disease is the most common disorder that can cause the eyes to protrude it is not the only one.
Protruding eyes, or a protruding eye, can also happen if there is something in the eye socket that pushes the eyeball forward. This could be:
- a cancerous or non-cancerous tumor
- a blood clot
- an eye injury
- orbital cellulitis (infection of tissue around the eye)
- abnormalities within the brain
Anybody who notices that one or both eyes are starting to bulge should seek medical attention.
A physician can normally notice a protruding eye by looking at it, but as exophthalmos is normally a sign of some disease or condition, tests will be needed to find the cause.
Tests may include:
- A blood test to see if the thyroid gland is functioning properly.
- Measurement of the degree of protrusion, using an exophthalmometer.
- Imaging scans, such as a CT scan or an MRI, to examine the orbit, or eye socket. A scan can detect a tumor or any abnormality in or around the eyes.
- A CT scan or MRI of the brain to evaluate the structure of the brain.
Exophthalmos tends to be a progressive disease, and symptoms get worse over time. Therefore, treatment should begin as soon as possible.
The ophthalmologist or eye specialist will monitor the person regularly.
Treatment depends on several factors, including the cause, the person's age, and their general health.
If the person has thyroid problems, the doctor will treat the underlying cause and bring thyroid hormone levels back to normal. While treating the thyroid problem is important, that alone may not resolve the exophthalmos. Often other treatments need to be added.
There are a variety of medical options for exophthalmos. Surgery can be helpful for those individuals with more severe eye involvement.
Non-surgical options for treatment can include:
- natural tears for eye lubrication
- sunglasses for light sensitivity
- medications that decrease the immune response, such as cyclosporin
- medications that block certain antibodies, such as rituximab (Rituxan)
In the case of radiotherapy, low dose radiation treatment is usually reserved for more severe cases and is often combined with corticosteroids.
Surgical options for treatment can include:
- Orbital decompression: Enlarging the orbit of the eye can make more room for the eye and its muscle and tissue.
- Eye muscle surgery: This can be done to correct abnormal eye muscles.
- Eyelid surgery: This works by protecting the cornea and outer eyeball from damage.
If left untreated, the eyelids may fail to close during sleep, resulting in the cornea drying and being damage. If the cornea dries out too much, there is a risk of infection or ulcers, which can damage vision.
People with exophthalmos are more likely to develop conjunctivitis, and especially superior limbic keratoconjunctivitis, in which the area above the cornea becomes inflamed due abnormal tearing and blinking.
Rarely, some people may experience compression of the optic nerve or ophthalmic artery, which can eventually affect the eyesight, and possibly lead to blindness.
Overall, the first step for any individual who notices bulging eyes is to seek medical care. Remember, exophthalmos is a sign that something more is going on, in or around the eye or within the brain.
The most common cause of exophthalmos is Graves' disease. It is important to work closely with the medical team to come up with a treatment plan to manage any thyroid problems, along with any eye complications. Quitting smoking is key for improving the outcome of exophthalmos, while close follow-ups will ensure the best care possible.