What is Thyroid Eye Disease?

Thyroid eye disease (TED) is a rare autoimmune disease. Autoimmune means that the body’s immune system cannot tell the difference between healthy cells and invaders like viruses, fungi, or bacteria. Because it cannot tell the difference, the body begins to attack and damage healthy cells.1,2

Antibodies are proteins your body makes to kill germs. In TED, harmful antibodies attack various parts of the body, including the tissues around the eyes. This results in inflammation and damage to the muscles, connective tissues, and fat around the eyes. Damage and inflammation is progressive, with an active and inactive phase.1,3

Thyroid eye disease is called many different names, including:5

  • Graves’ eye disease
  • Graves’ ophthalmopathy (GO)
  • Graves’ orbitopathy
  • Thyroid-associated ophthalmopathy (TAO)
  • Thyroid orbitopathy

TED and Graves’ disease are separate conditions. The different names for TED adds to the confusion that both conditions may occur together but are not necessarily caused by the other.1

Symptoms

Symptoms of TED are highly variable from person to person. Eye symptoms range from mild to severe, including:6

  • Eyelids pulling back (retraction and lateral flare)
  • Bulging eyes (proptosis, prop-toe-sis)
  • Sensitivity to light
  • Vision changes
    • Double vision (diplopia, dip-low-pee-uh)
    • Blurred vision
    • Loss of color vision
    • Eye focusing problems
    • Vision loss
  • Eye pain and pressure
  • Misaligned eyes that do not line up and point in different directions (strabismus, struh-biz-miss)
  • Eye inflammation
    • Red eyes
    • Watery eyes
    • Swelling of the clear membrane of the eye (chemosis, key-moe-sis)
    • Swelling of tissues around the eye
    • Eyelid swelling
  • Open sores on the surface of the eye (corneal ulcers)
  • Compression of the nerve fibers in the eye (optic nerve compression)

Who gets TED?

About 19 in every 100,000 people have TED. TED occurs more often in women than in men. However, men are more likely to have a severe form of TED than women. The disease is most likely to occur in middle age but can occur at any age. TED is more rare in children.7,8

What causes it?

Your thyroid is a butterfly-shaped organ located at the base of your neck, below your Adam’s apple. This gland secretes thyroid hormones. Thyroid hormones play an important role in nearly every body function. The main function of the thyroid gland is metabolism, or the speed at which your body cells work.3,4

If your thyroid makes too much of a hormone called thyroxine, hyperthyroidism (overactive thyroid) results. Insulin-like growth factor 1 receptor (IGF-1R) is a protein that is connected to the thyroid hormone. Too much thyroxine turns on the IGF-1R protein. This causes muscle, fat, and connective tissue cells around the eyes to grow. Too much growth of these cells causes the symptoms of TED.3

Graves’ disease

Graves’ disease is an autoimmune disease that results in an overactive thyroid (hyperthyroidism). Graves’ disease affects 1 in every 200 people in the United States.9,10

A part of the brain called the pituitary gland makes and releases a hormone called thyroid-stimulating hormone (TSH). TSH tells the thyroid how much thyroid hormones (known as T3 and T4) to make. If the levels of T3 and T4 drop too low, the pituitary gland makes TSH, and more thyroid hormones are made by the thyroid gland.9,10

In Graves’ disease, the body makes an abnormal antibody (thyroid-stimulating immunoglobulin, or TSI). TSI mimics TSH and tricks the body into thinking it needs more thyroid hormone. This causes the body to make too much T3 and T4, leading to an overactive thyroid and increased metabolism.9,10

Because TSI is a harmful antibody, it begins to attack normal cells and proteins in the thyroid. Doctors think the proteins around the eye are similar to those in the thyroid. This explains why TSI also attacks the tissues around the eye. This leads to the symptoms of TED.1,3,9

Up to half of those with Graves’ disease develop TED. Despite this link, TED and Graves’ disease are separate conditions requiring different treatment. Each disease runs its own course, and they do not always occur at the same time.11

Thyroid function

In 8 to 9 out of every 10 cases, TED is caused by an overactive thyroid. This is the result of hyperthyroidism or Graves’ disease.3

However, about 1 in 10 people with TED have lower thyroid function, or hypothyroidism. The most common cause of hypothyroidism in the United States is Hashimoto’s thyroiditis. Like Graves’ disease, Hashimoto’s thyroiditis has harmful antibodies that attack the thyroid.3

Most people with TED will have either too much or too little thyroid hormone. However, about 1 in every 100 people have a normal-functioning thyroid (euthyroid).3

Risk factors

Smoking and secondhand smoke exposure are the leading risk factors for TED. Those who smoke are 7 to 8 times more likely to get TED. Other risk factors include:11,12

  • Family history of TED
  • History of radioactive iodine therapy
  • History of other autoimmune disorders
  • High blood cholesterol

Treatment

Because smoking greatly increases the risk for TED, stopping smoking is the first step doctors will recommend. Keeping thyroid hormones within a normal range might help with the disease, though this is not always the case. Your doctor will guide you on thyroid medicine that may help.7

Treatment for TED depends on the phase you are currently in. Various treatment for TED includes:7

  • Steroids
  • Drugs that work on your immune system (called immune modifiers or biologics)
  • Surgery, in some cases

Course of the disease and outcomes

TED typically has a progressive inflammatory active phase and an inactive phase. The initial (acute) phase can last from 6 months to 1 year and is highly variable from person to person. An inactive phase follows, where disease progression stops but some symptoms remain.1

TED is not considered life-threatening, but it can impact countless areas of your health and well-being. While treatments may help improve symptoms, those with TED are often met with physical and emotional hurdles. Living with the unpredictable nature of TED can cause challenges to many aspects of daily life.1

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Written by: Katie Murphy | Last reviewed: October 2021