Looking in the mirror and seeing one or both eyes bulging can be startling, especially if you aren’t sure why it’s happening. One possible cause of proptosis (eye bulging) is thyroid eye disease (TED), which can be a result of Graves’ disease. You might be especially concerned if you notice that one eye appears to be bigger than the other.

Read on to discover whether differences between your eye sizes might be related to Graves’ disease or TED.

Graves’ Disease and Thyroid Eye Disease

Graves’ disease is an autoimmune condition. This means the body’s natural immune system ends up attacking itself. Typically, Graves’ disease results in hyperthyroidism, where the body produces too much thyroid hormone.

Because hormones circulate around the body, hyperthyroidism can lead to many symptoms. When it affects the eyes, it can cause Graves’ ophthalmopathy, also known as thyroid eye disease, Graves’ eye disease, or Graves’ orbitopathy. The immune system produces antibodies that target tissues around the eyes, causing swelling and inflammation.

Thyroid Eye Disease

TED is also an autoimmune disease. It causes inflammation of the area around your eyes, which leads to various eye symptoms:

• Bulging eyes (proptosis or exophthalmos, which refers specifically to bulging caused by thyroid issues)
• Dry or watery eyes
• Vision changes such as double vision or vision loss
• Red or irritated eyes
• Pain around the eyes

These symptoms typically affect both eyes but can impact just one. The bulging of one or both eyes occurs for a few reasons. The eyeball can be pushed forward in the socket because of inflammation and enlargement (from swelling) of the tissues behind the eye. This is a result of the immune system mistakenly attacking the healthy tissue. It can also occur when the immune system attacks the eye muscles, causing them to thicken and stiffen and as a result, the eyeball is pushed forward. When the muscles of the eye are targeted, they can also pull back the upper eyelid. This gives the eye a bulging appearance as well.

TED Symptoms in Just One Eye

TED can affect both eyes evenly (symmetrically), one side more than the other (asymmetrically), or just one eye (unilateral TED). More severe or active disease tends to show up as asymmetry, and about 9 percent to 34 percent of cases are asymmetrical, while 4.5 percent to 14 percent involve only one eye.

The reasons TED affects one side more than the other are not well understood. Some research suggests it might be related to differences in facial structure, such as variations in eye socket size or the number of blood vessels and immune cells around the eye. Even if TED starts asymmetrically or unilaterally, it may eventually affect both sides equally, though this is not always the case.

Risk Factors for TED

Graves’ disease is a common condition that leads to TED. About 33 percent of those with Graves’ disease will end up with TED.

Other risk factors for TED include:

• Being female — Females are four times more likely to develop TED than males, according to research in Clinical Endocrinology.
• Being middle-aged — The condition most commonly develops in people ages 40 to 60.
• Having certain genetics — A family history of thyroid or autoimmune diseases increases the risk of TED.
• Smoking — People who smoke are seven to eight times more likely to develop TED than those who don’t.
• Undergoing radioactive iodine therapy — This treatment for hyperthyroidism can trigger or worsen TED.
• Having other thyroid problems — Both hyperthyroidism and hypothyroidism (underactive thyroid) can increase the risk.
• Having autoimmune disorders — Conditions like type 1 diabetes or rheumatoid arthritis are linked to a higher risk.
• Being deficient in certain vitamins — Low levels of selenium or vitamin D have been associated with a higher risk of TED.

Diagnosis and Treatment

There is some overlap between how Graves’ disease and TED are diagnosed and treated. It’s important to talk with a health care provider — such as an endocrinologist or ophthalmologist — to find the best options for your situation.

Diagnosis of Graves’ Disease

Your doctor will take a thorough history to understand which symptoms you’ve been experiencing. Diagnostic tests for Graves’ disease may include:

• Blood tests — These check the levels of thyroid hormones in your body, helping to determine if you have hyperthyroidism.
• Radioactive iodine uptake test — In this test, you will take a small amount of radioactive iodine, and your doctor will measure how quickly your thyroid absorbs it. This test can help confirm if your thyroid is overactive, which is a common sign of Graves’ disease.

Diagnosis of Thyroid Eye Disease

Like with Graves’ disease, your doctor will start by reviewing your medical history. A blood test may be done to check your thyroid hormone levels. Your doctor will also perform an eye exam to assess how well your eyes are functioning, determine if there are any alignment issues, and check for bulging. Your doctor may also order imaging tests, such as an MRI, CT scan, or ultrasound, to get a detailed view of the tissues around your eyes.

An ophthalmologist may determine that your eye problems are due to a condition other than TED. Other possible causes of eye bulging include:

• Infection or inflammation — Infections or inflammatory conditions in the eye tissue can lead to swelling.
• Injury to the eyes — Trauma to the eyes or surrounding areas may cause bulging.
• Tumors in or around the eyes — Conditions like neuroblastoma (a cancer that develops from immature nerve cells) or sarcoma (a cancer that forms in bones or soft tissues) can cause growths that push the eye forward.
• Bleeding or changes in blood vessel structure — Issues behind the eyes can lead to bulging due to blood vessel abnormalities.
• Glaucoma — This condition can damage the optic nerve and may cause changes in the appearance of the eyes.

Treatment for Graves’ Disease

Treatment for Graves’ disease focuses on slowing or stopping the production of thyroid hormones and blocking their effects on the body. Treatment options include:

• Radioactive iodine therapy — This targets the thyroid gland to shrink the cells that make the hormone.
• Antithyroid medication — These medications will block the thyroid from making hormones.
• Beta-blockers — These medications don’t lower hormone levels but reduce the effects of excess thyroid hormones on the body, such as rapid heart rate or anxiety.
• Surgery — In some cases, a thyroidectomy (removal of the thyroid gland) may be recommended to permanently stop hormone production.

Treatment for Thyroid Eye Disease

There are many treatment options for TED. Medications can help manage symptoms of TED. Surgery is an option for some people. For instance, a doctor may recommend orbital decompression or decompression surgery to relieve pressure around the eye. Surgery might also be performed to allow the affected upper eyelid to close fully or to improve double vision. In more severe cases, eye muscle surgery may be needed to correct double vision.

Eyedrops, ointments, or gels can help relieve dry eyes (especially for those who have difficulty closing their eyelids fully). If there’s an infection, antibiotics may be prescribed.

Other ideas to help manage symptoms of TED include:

• Wearing sunglasses — Protects your eyes from light and wind, especially if they bulge
• Using a cool compress — A damp cloth or cool compress can reduce swelling and irritation.
• Using eyedrops or artificial tears — Helps keep your corneas moisturized and prevents dryness
• Having your eyelids taped shut while you’re sleeping — Prevents the eyes from drying out if your eyelids don’t fully close
• Sleeping with your head elevated — Reduces pressure in your eyes, which can help with swelling
• Managing double vision — May include wearing a patch over one eye or using special prism glasses

One member of the TEDhealthteam community shared, “I use eyedrops during the day and sleep with a moisture mask at night.”

Talk to Your Doctor

If you notice one or both of your eyes bulging, it’s important to see your doctor. Although TED is a common cause, other issues like infections, injuries, or tumors can also lead to eye bulging. A medical evaluation is crucial to identify the cause and prevent potential complications.

Your doctor can offer treatment options tailored to your needs, whether managing TED or addressing other conditions. Early diagnosis and intervention can protect your vision and eye health, so don’t wait to seek help.

Talk With Others Who Understand

TEDhealthteam is the social network for people with thyroid eye disease and their loved ones. On TEDhealthteam, hundreds of members come together to ask questions, give advice, and share their stories with others who understand life with TED.

Are you living with TED? Have you noticed a change in your eye size? Share your experience in the comments below, or start a conversation by posting on your Activities page.