Thyroid eye disease: Causes and treatments
What is thyroid eye disease?
Thyroid eye disease (TED) is an autoimmune condition in which your body’s immune system has started attacking the thyroid gland. Treatment includes medications and procedures to control thyroid hormone levels, along with eye drops and ointments to treat symptoms such as dry eye.
Thyroid eye disease is a confusing condition. It’s often mild but it can also be severe enough to threaten your eyesight.
Thyroid eye disease is usually linked to levels of thyroid hormones that are too high (hyperthyroidism), but it also can occur in people whose hormone levels are too low (hypothyroidism) and even in those who have normal thyroid hormone levels.
Thyroid eye disease is often considered part of another condition called Graves’ eye disease, but it can occur without Graves’ being present.
Even the name of the condition — or at least what to call it — can be confusing. Thyroid eye disease can also be called Graves’ ophthalmopathy, thyroid-associated orbitopathy, thyroid ophthalmopathy or Graves’ eye disease.
Symptoms of thyroid eye disease
The symptoms of thyroid eye disease include dry eyes, itchy or gritty-feeling eyes, swollen eyelids, watery eyes, bulging eyes, misaligned eyes and double vision.
Thyroid eye disease may affect one of your eyes more than the other.
If severe and left untreated, thyroid eye disease can damage your corneas or increase the pressure inside your eyes — which can damage your optic nerve — either of which can harm your overall vision.
However, only about 10% to 20% of people with thyroid eye disease have it severely enough to possibly damage their eyesight, according to the Kellogg Eye Center at the University of Michigan.
Thyroid eye disease often causes inflammation of the surface of your eye, including the sclera (the whites of your eyes) and corneas. Your eyes may not form enough tears or may be watery. The muscles and tissue behind and around your eyes may become swollen, which pushes your eyeballs forward and pulls the eyelids up higher, causing more of your corneas and sclera to be exposed to air and drying your eyes even further.
If the eye is pushed far forward, your eyelids may not be able to close properly.
If you have Graves’ eye disease in addition to TED, you may also experience symptoms like fatigue, irritability, anxiety, rapid heartbeat, excessive sweating, and sensitivity to heat or cold.
Because thyroid eye disease can be mild, you may not find out you have it unless you are diagnosed with other thyroid issues. You may also go through periods in which the condition flares up and other times when the symptoms subside for a while.
What causes thyroid eye disease ?
Let’s back up a bit and explain how TED is related to your thyroid.
The thyroid is a gland in your neck that creates hormones which control your growth during childhood; help control your metabolism; and help regulate functions like your heart rate, sleep patterns and some parts of sexual function.
Thyroid eye disease may result in Graves’ eye disease, in which the thyroid produces too much of the thyroxin hormone (also called hyperthyroidism). The same autoimmune response also attacks the tissue around and behind your eyes, including the muscles that help move your eyes, sclera and corneas.
But, here is another confusing factor: About 10% of people with thyroid eye disease have hypothyroidism, which means their thyroid does not produce enough thyroxin. An even smaller percentage of people with TED have normal thyroid levels.
Not everyone with abnormal hormone levels gets thyroid eye disease. Between 25% and 50% of patients with either hyperthyroidism or hypothyroidism will develop some form of TED, according to an article in Review of Ophthalmology.
Once thyroid eye disease starts, it may continue even if thyroxin levels are later controlled. However, having poorly controlled thyroxin levels will usually cause TED to get worse.
As with many autoimmune conditions, more women than men have thyroid eye disease. TED is more common in people who smoke, and stress can cause the disease to flare up.
What are treatments for thyroid eye disease ?
Thyroid eye disease will most likely be diagnosed first by your general physician, who may then refer you to an ophthalmologist. You will probably also need to see an endocrinologist, a physician who treats hormonal conditions.
Either your general physician or your endocrinologist will take blood samples to test for levels of thyroid hormones.
If you have Graves’ eye disease and have hyperthyroidism, there are several treatments — including prescription medications — that will help lower and control your thyroid hormone levels.
If your hyperthyroidism is serious, you may also need to undergo a procedure that uses radiation to reduce the thyroid gland or surgery to remove it. If you need this procedure, you will need to take replacement thyroid hormone for the rest of your life and have blood tests once or twice a year to ensure that your hormone levels are in the right range.
Hypothyroidism is usually treated with replacement thyroid hormone, but this treatment may not have a direct effect on your thyroid eye disease. You will probably need thyroxin replacement for the rest of your life along with regular blood tests.
Many people with mild TED do well by treating the symptoms of the condition. Ophthalmologists prescribe artificial tear products or ointments and anti-inflammatory eye drops.
In January 2020, the Food and Drug Administration approved a drug called Tepezza (Teprotumumab) to treat thyroid eye disease in adults. It works by treating the inflammation of the tissues behind and around the eye. An intravenous drug, Tepezza is administered every three weeks (for a total of seven treatments) in outpatient clinics.
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Published February 2020