Overview   

Thyroid eye disease (TED) is an autoimmune condition closely related to Graves' disease. This condition affects the eye as the immune system will mistakenly start attacking the tissue around the eyes. This will cause inflammation, swelling and changes to the eye structure and function. While TED is not life-threatening, the symptoms that range from bulging eyes, dryness, redness and double vision can really impact your vision and the quality of your daily life. In the worst case, it's possible to have visual impairment. 

When you know the signs of TED, it's easier to spot it early and manage the symptoms. Having TED can make you more insecure about your look and make day-to-day tasks harder due to the visible changes. Which is why it’s important to find a treatment that works. This article will talk about how TED starts, its key signs, and the ways to treat and manage it.¹

Pathophysiology of Thyroid Eye Disease

TED happens when your immune system mistakenly attacks the tissues that are around the eye. This is what leads to the redness, swelling and bulging. In the centre of the process, there are special eye socket cells known as orbital fibroblasts. In people who have TED, these special cells will react to certain immune signals, which makes them grow and release substances that cause inflammation and tissue buildup. This is what makes the eyes bulge forward, creating a bulging appearance. 

The inflammation will also bring more cells that are immune cells into the area, which will make the swelling worse. Over time, this swelling leads to eye pain, irritation and redness. Sometimes the swelling can also press onto the eye muscle, causing double vision.²

Major Symptoms of Thyroid Eye Disease

Bulging Eyes

Bulging eyes, or proptosis, are a clear sign of TED. When the tissue behind the eyes swells, the eyeball is pushed forward, making the eyes look more protruding. This can make it harder for the eyes to close fully, making the eye more exposed and vulnerable to irritation and dryness. In severe cases, exposure keratopathy may occur, where there is a lot of damage to the cornea from the excessive exposure.^1,3

Dryness  

When the eye is pushed forward because of TED, the natural layer of tears that keeps the eye moist is disrupted. This will make it harder to blink and spread tears evenly, which causes dryness and irritation. People with TED may also feel a gritty sensation in their eyes, become more sensitive to light, and develop eye pain. Over time, this dryness can make it harder to continue their daily tasks, such as reading.^1,3

Redness 

TED can also cause inflammation in the conjunctiva (this is a thin layer that covers the white part of the eye). This will lead to redness, swelling, and a burning sensation. You might also feel pressure in your eyes or pain that may seem like it's just allergies. If inflammation isn't treated, it can damage the cornea ( surface of the eye).^1,3  

Double Vision

When TED progresses, the extraocular muscles that control the eye become more swollen. This can cause double vision (diplopia). People with double vision may struggle with tasks that require precise vision such as driving. In some cases, the misalignment in the eye can become permanent, and surgery may be needed to bring back normal eye function.^1,3

Diagnosis and Assessment 

TED can stem from many sources, so doctors will test for other causes before it is called TED. Bulging eyes in grown-ups are often due to TED, yet it may also come from tumours, infections, or other conditions. Double vision may be caused by TED, but it may also happen with conditions such as myasthenia gravis or orbital tumours. A blood test can check for TED by testing how well the thyroid works and by looking for certain antibodies that show a thyroid problem.   

CT scans and MRI tests are also useful in diagnosing and monitoring TED. CT scans help by giving detailed images of the eye socket, which is important before surgery, while  MRI tests are good for spotting inflammation and soft tissue changes. Another test that's not so common is an orbital ultrasound; this is a quick and radiation-free way to check for swelling. Or you can also have Octreoscan, which spots inflammation. Overall, in the majority of cases, TED can be diagnosed without a biopsy, but if a doctor suspects cancer, a small tissue sample can be taken for testing.^3,5

Treatment and Management 

TED can be mild or severe, a mild case can get better on its own, while severe cases might need stronger treatment to help protect the eye’s vision. Managing TED involves both treating the eye condition and the thyroid problem.

Managing Thyroid Levels: Keeping the thyroid hormone levels normal can help prevent TED from getting worse. Medications and surgery for hyperthyroidism does not make TED worse, but a treatment known as radioactive iodine can increase the risk of eye problems. This risk however can be reduced by a short course of steroids. Smoking is also another risk factor, so quitting is the best option.

Mild TED treatment: 

• Using lubricating eye drops to ease dryness
• Sleeping with your head raised to prevent swelling
• In some cases, you can take selenium supplements 
• Avoiding steroids and radiotherapy unless it's needed  

Moderate to Severe TED treatment: 

• Steroids: This is usually the first treatment.  IV steroids work better than oral ones, but they may lead to weight gain or shifts in mood
• Radiotherapy: This can aid in eye movement, but it's not wise for young people or those who suffer from diabetes to use this method
• New Treatments: Some newer drugs can help reduce inflammation and eye bulging. This can include targeted therapies such as teprotumumab which is FDA approved for TED
• Surgery: In severe cases, surgery may be needed to fix the eye misalignment^3,4,6

Summary

Thyroid eye disease can be a very distressing condition both emotionally and physically. TED's symptoms- bulging eyes, dryness, redness and double vision can significantly impact your daily life. Although when you know these signs are suggestive of TED, you can get help sooner and receive the right care to prevent long-term effects. Identifying TED early and treating it quickly are both vital in preventing loss of sight or long-term damage to the eyes. With the discovery of various treatment methods for mild and moderate TED, it’s always best to see a doctor as soon as possible when you experience the symptoms or if you have issues with your thyroid.