What Is Orbital Radiotherapy?

Reviewed by: HU Medical Review Board | Last reviewed: September 2023

Thyroid eye disease (TED) can lead to swelling behind and around the eyes. This occurs in phases. The active phase of TED causes inflammation, swelling, and irritation. Symptoms of TED continue to worsen the longer the active phase continues.1

During the active phase, stopping the inflammation from TED is challenging. Steroids, which are strong drugs to reduce inflammation, are often used but have serious side effects. Surgery that corrects function and facial appearance is usually performed in the inactive phase only.2

New drug therapies help decrease the inflammation and damage caused by TED. These new drugs work on the cause of TED rather than just treating the symptoms. Other nonsurgical options might also be effective for treating the disease.2

What is orbital radiotherapy (ORT)?

Orbital radiotherapy (ORT) is a treatment given to decrease inflammation caused by TED. ORT involves low-dose radiation delivered to and around the eyes. Therapy is usually performed in an outpatient setting with divided doses over multiple visits.3

How does it help treat thyroid eye disease?

ORT works by decreasing the autoimmune response of TED. ORT helps fight off the effects of the body’s own immune system mistakenly attacking healthy tissue. ORT also helps to prevent swelling of tissue in and around the eye socket. ORT can also help decrease swelling and tightening of the muscles responsible for moving the eye.3

Studies have shown that ORT works better to decrease swelling when used with steroids. Doctors have studied ORT for many years and have found it is a safe treatment for the active (acute) phase of TED.3

ORT versus radioiodine treatment

Many people with TED have an overactive thyroid (hyperthyroidism). Radioiodine (RAI) treats overactive thyroid and certain types of thyroid cancer.4

While also well-tolerated, those who have had RAI in the past are at greater risk of developing TED. For those with TED, RAI has been linked to worsening symptoms of TED.4

Orbital radiotherapy is a treatment for TED, while RAI is a risk factor for developing TED.4

What are the possible side effects?

Like other procedures, ORT has possible side effects. Many of these side effects are mild and affect the area of treatment only, including:3

  • Skin redness
  • Hair loss around the temples

ORT can cause problems to the retina, which is the thin layer of tissue that lines the back of the eye. Retinal disease is called retinopathy. Conditions that affect the small blood vessels can cause retinopathy, such as:3,5

  • High blood pressure (hypertension)
  • Diabetes

Those with diabetes and high blood pressure are at increased risk of retinopathy after ORT and should not have ORT.3

ORT can increase the risk of developing a cataract or clouding the eye’s normally clear lens.6

These are not all the possible side effects of orbital radiotherapy. Talk to your doctor or TED specialist about what to expect or if you experience any changes that concern you during or following your treatment with ORT.

Things to know about ORT

Medical insurance carriers may or may not cover new treatments for TED. ORT might be a good option for those who struggle with medical insurance coverage. Also, some people with TED might prefer nonsurgical options like ORT.3

Despite advances in treatment, much uncertainty remains for those with TED. Studies have had mixed results on how effective ORT is for TED. While some studies show improvements in symptoms of TED, others do not. This adds to the complex nature of TED.3

Treatment for TED is not a one-size-fits-all. Everyone is different, and ORT might be useful for some and not for others. Talk to your TED specialist about ORT, its risks and benefits, and whether or not it is a treatment option for you.

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