Radiation for Thyroid Eye Disease

Thyroid eye disease is a rare autoimmune disorder that irritates and damages the eye muscle and fatty tissue behind the eyes. Orbital radiation therapy (ORT) can slow and may even reverse eye damage in people with thyroid eye disease.

The earlier you start ORT, the higher the chances of preserving your sight and improving symptoms of thyroid eye disease.

Thyroid eye disease primarily affects people living with Graves’ disease — an autoimmune disease in which the immune system stimulates the thyroid gland in the neck. The thyroid responds to this by enlarging and releasing too much thyroid hormone into the circulation.

The immune system also attacks tissues and muscles in the eye, possibly because they contain proteins that are similar to proteins in the thyroid gland. This causes the connective tissues and muscles in the eye swell. 

Symptoms of thyroid eye disease include:

• blurred or double vision
• bulging or staring eyes
• difficulty moving the eyes
• dry or watery eyes
• light sensitivity
• pain in the eyes
• redness and irritation of the eyes and eyelids
• swelling of the eyelids

Thyroid eye disease has an active phase that can last from 6 months to 2 years. This is when most of the inflammation and damage happen in the eye. The longer you’re in the active phase, the harder it is to reverse symptoms like bulging eyes and double vision. 

Early treatment can help to protect your eyes’ appearance and vision.

For mild thyroid eye disease, treatments to manage symptoms may be enough. Artificial tears relieve dryness, dark sunglasses help with light sensitivity, and special glasses with prisms attached correct double vision.

One medication approved by the Food and Drug Administration (FDA) to treat thyroid eye disease is teprotumumab trbw (Tepezza).

This medication blocks the protein insulin-like growth factor-1, which is involved in causing symptoms of the disease. Tepezza helps reduce eye bulging and double vision. 

If your thyroid eye disease is more severe, you may need high-dose corticosteroids to reduce orbital inflammation. Long-term use of high-dose corticosteroids is discouraged because it frequently yields serious adverse events. Surgery is sometimes needed to correct double vision, improve the appearance of the eyelids, or create more space in the eye to accommodate for swelling.

ORT uses low doses of radiation to reduce inflammation in the eye. It works by reducing the activity of inflammatory immune cells that attack and damage your eyes. 

Your doctor might recommend this treatment if you have moderate to severe thyroid eye disease and steroids haven’t helped you enough or you can’t take steroids. ORT is also an option if thyroid eye disease has affected your eye movement, or it has put enough pressure on your optic nerve to threaten your sight.

You’ll typically get radiation once a day for 10 days. Your doctor may prescribe steroids at the same time as ORT to maximize the anti-inflammatory effects. 

Radiation isn’t recommended if you have mild thyroid eye disease. Managing your symptoms may be enough in that case.

A 2021 study suggests this treatment is useful for improving eye movement, double vision, and symptoms like pain and watery eyes. ORT may also help to prevent optic neuropathy — pressure on the optic nerve from swollen eye muscles that can lead to vision loss. This treatment may not be as helpful for bulging eyes or eyelid problems. 

A 2020 study suggests ORT works just as well as steroids at treating thyroid eye disease. Radiation therapy starts to work more slowly than steroids, but its effects last longer. Some people who get ORT can lower their steroid dose or stop taking steroids altogether. 

ORT is generally safe. The most common side effects may be dry eye and cataracts. 

A small number of people who get ORT develop damage to the blood vessels in the back of their eye, called retinopathy. Living with diabetes or high blood pressure increases the risk of retinopathy. Your doctor might not recommend this treatment if you have one of these conditions. 

Because thyroid eye disease involves both your thyroid gland and eyes, treatment may involve more than one specialist. Your treatment team could include an ophthalmologist, a primary care doctor, and an endocrinologist (hormone specialist). 

Talk with your doctors about the different treatment options, including radiation therapy. Ask how ORT can help protect your sight, prevent eye changes, and what side effects it might cause.