Thyroid Eye Diseases Causes, Symptoms, Prevention & Treatment

Photo by JeevaMuthuramalingam, CC BY-SA 4.0, via Wikimedia Commons

Thyroid eye disease (TED) is a condition in which the muscles and fatty tissues around the eye become inflamed and swollen. This can push the eye forward, so the eyes look bulging or staring.

The muscles that move the eye can also swell, so the eyes no longer line up and you see double. Rarely, swelling presses on the optic nerve and threatens vision, which needs urgent treatment.

Why do thyroid eye diseases occur? TED is an autoimmune disease: the immune system attacks the muscles and other tissues around the eyes. It is most often linked to Graves' disease, an autoimmune cause of an overactive thyroid (hyperthyroidism), and is also called Graves' ophthalmopathy.

According to the NIDDK, more than 1 in 3 people with Graves' disease develop this eye disease. It can also occur when thyroid levels are normal.

Classical Symptoms of Thyroid Eye Diseases

Eye symptoms can start before, at the same time as, or rarely after the thyroid problem. You need to call your doctor if you have any of the following symptoms:

Dry eye
Excessive tearing of the eye
Staring or bulging eyes
Gritty sensation in the eyes
Inflammation of the eye
Puffy eyelids or bags under the eyes
Redness
Eye Disease that causes Blindness warning signs, such as blurred vision or dim colors
Swelling or fullness in one or both upper eyelids
Irritation
Double vision
Difficulty in eye movements
Forward bulging of the eye, often called proptosis
Pain or pressure in the eyes, especially during eye movements
Sensitivity to light, or photophobia

Sometimes TED is hard to diagnose because its symptoms resemble conjunctivitis, allergies or other eye conditions. Some features point more toward TED:

Double vision
Pain in or behind the eyes during movement
Symptoms that don't change with the season
Little or no itching, unlike allergic conjunctivitis

Causes of Thyroid Eye Diseases

Thyroid eye disease is an autoimmune condition. It often occurs with graves Eye diseases, in which the immune system makes an antibody that tells the thyroid gland to make too much thyroid hormone. The thyroid hormones T3 and T4 speed up the body's metabolism.

Too much thyroid hormone can cause a fast heartbeat, palpitations, sweating, irritability, heat intolerance, weight loss, fatigue and hair thinning. A sudden, severe worsening called thyroid storm is a medical emergency.

The eye disease itself comes from inflammation of the soft tissues and muscles around the eye. Smoking makes it worse, and stressful life events can trigger flares. Early diagnosis and treatment help protect the eyes.

Tests and Diagnosis

If you have the symptoms above and your doctor suspects a thyroid problem, these tests may be used to confirm the diagnosis.

1- Thyroid Function Tests

Blood tests measure TSH and the thyroid hormones T4 and T3. In hyperthyroidism, TSH is usually low and T4 or T3 is high. Blood tests can also check for the antibody that causes Graves' disease.

2- Imaging

An eye doctor examines the eyes and may order a CT scan or MRI of the eye sockets. These scans show swollen eye muscles and help rule out other causes.

3- Thyroid Scan

A radioactive iodine uptake test measures how much iodine the thyroid takes up from the blood. You swallow a small amount of radioactive iodine, and a scan shows how it spreads through the thyroid gland.

In Graves' disease, the iodine shows up throughout the whole gland.

4- Tissue Extraction

If the thyroid has nodules, a doctor may do a fine needle aspiration (FNA) biopsy. A thin needle takes a small sample of thyroid cells to send to a lab. This test checks the nodules; it is not used to diagnose the eye disease.

Treatment for Thyroid Eye Diseases

Treatment depends on how severe and how active the eye disease is. An ophthalmologist and an endocrinologist often work together on care.

For Mild Disease

Most cases are mild. Lubricating eye drops can relieve dry, gritty, irritated eyes, and sunglasses can help with light sensitivity.

Sleeping with your head raised may reduce eyelid puffiness. Taping the eyelids shut at night or wearing an eye mask can help if your eyes don't fully close. Special prism lenses may help with double vision.

For Severe Disease

For moderate to severe disease, doctors may use steroids or other medicines that calm the immune response. Teprotumumab, an infused medicine, was approved by the FDA in 2020 as the first drug for thyroid eye disease.

Surgery can relieve pressure on the optic nerve, reduce bulging, or correct double vision and eyelid position. Radiation therapy to the eye tissues is used rarely.

The overactive thyroid is treated separately with antithyroid medicine, radioiodine therapy or surgery. Radioiodine can make eye symptoms worse, so tell your doctor if you have eye problems. If the whole thyroid is removed, you will need thyroid hormone medicine for life.

Important Preventative Tools

You cannot always prevent thyroid eye disease, but these steps can lower the risk of it getting worse:

Quit smoking, as it aggravates the symptoms and worsens the condition.
Keep thyroid hormone levels stable by taking medicines exactly as prescribed.
Avoid sudden swings in your thyroid hormone levels. Get regular blood tests and follow your doctor's advice.
Don't start supplements, including iodine or selenium, without talking to your doctor first.
You should have regular eye checkups with an ophthalmologist to catch changes early.
Report new double vision, vision loss or eye pain to your doctor right away.