Thyroid Eye Disease Phases

Thyroid Eye Disease (TED) is a serious, potentially vision-threatening condition that can get worse over time, but can be managed with treatment. When you have TED, your immune system mistakenly attacks the muscle and fat tissue behind your eyes, causing inflammation (redness and swelling) and scar tissue to form. TED has 2 phases. The first is called the “acute” phase, which you may hear your doctor describe as the “active” phase of TED. The second is called the “chronic” phase, which you may hear your doctor call the “inactive” phase of TED.

Learn what is happening to your eyes with TED

Thyroid Eye Disease (TED) and Graves' disease are both autoimmune disorders. While TED often develops in people who have Graves' disease, they are different conditions. That's why they require different doctors and different treatments.

Graves' disease affects the thyroid. TED affects the muscle and fat behind the eyes. Both diseases affect the eye, but in different ways. Watch the video below to learn more about the differences between TED and Graves' disease, and TED risk factors.

Read transcript

Announcer: Thyroid Eye Disease (or TED) is a rare disease affecting the eyes. TED is also referred to as Graves’ Eye Disease. TED can develop in patients with Graves’ disease. Although they are both autoimmune conditions, TED and Graves’ disease are different conditions as they affect different parts of the body. 

In Graves’ disease, the body mistakenly attacks the thyroid glands, resulting in an overactive thyroid, or hyperthyroidism. In TED, the immune system attacks the muscles and fat tissues behind the eyes, causing redness and swelling known as inflammation. This process results in both the muscles and fat tissues behind the eyes expanding, as well as a buildup of fluid. 

Treatments for Graves’ disease are targeted to help the thyroid but won’t help TED. Different medications and specialists are required to manage each condition. Some of the early symptoms of TED are eye pain, redness, dry or gritty eyes, or overly watery eyes, and blurry vision. These symptoms can be mistaken for other conditions, such as allergies. 

TED is a progressive disease, which means it can get worse over time. Bulging eyes and eyelid swelling may occur as TED progresses. Eye swelling can make it hard to move the eyes. All these effects can lead to vision impairment, including double vision. In some cases, it is possible for swelling of fat and muscle tissue to push against the optic nerve, which puts vision at risk. 

While it is not entirely known why some people develop TED and others do not, doctors have found certain factors that put people at greater risk. This includes having a thyroid condition such as Graves’ disease or hyperthyroidism, and Hashimoto’s disease, or hypothyroidism. The risk of developing TED may also be increased if patients have received radioactive iodine as treatment for Graves’ disease. In general, women are more likely to suffer from TED. Smoking and middle age further increase the risk of developing the condition. 

As a rare and complicated disease, TED treatment requires a specialist who is familiar with treating it. Doctors who are most familiar with TED are usually specialized ophthalmologists, such as oculoplastic surgeons, neuro-ophthalmologists, and strabismus surgeons. Remember, TED can get worse over time. Getting treatment as early as possible can help prevent further eye damage. 

Find a TED Eye Specialist at

When you first develop Thyroid Eye Disease, you may notice changes in symptoms

TED begins with an acute phase, which means that symptoms appear suddenly and often get worse. The acute phase can last from 6 months to 2 years. The inflammation (redness and swelling) and scarring that start to form during this phase can damage your eyes, and cause a number of changes.

You may notice the following appearance and vision changes:

  • Redness
  • Swelling
  • Dry, gritty eyes
  • Eye bulging
  • Double vision
  • Misaligned eyes or eyes that don’t work together
  • Sensitivity to light
  • Eye pain and pressure

The changes caused by TED may also affect your emotions, making you feel anxious or depressed.

Learn more about the symptoms and signs of TED as well as the impact it can have on your emotional well-being.

While the length of the acute phase of TED is different for everyone, it usually lasts between 6 months to 2 years. During this time, symptoms can change or continue to get worse. Ideally, treatment should be given during the acute phase.

What can Thyroid Eye Disease look like?



Thyroid Eye Disease may slow down over time, but that doesn’t mean it goes away

The acute phase is followed by the chronic phase of TED. You may have heard your doctor refer to this phase as the “inactive” phase of TED. However, that doesn’t mean your condition has gone away. You may still have symptoms during the chronic phase.

Only a TED Eye Specialist can determine which phase of TED you are in, but there are a few signs to watch for that may signal you are entering the chronic phase:

  • Inflammation (swelling) has stopped or slowed
  • Redness has decreased or gone away
  • Eye bulging hasn’t gotten worse

Inflammation that began during the acute phase can cause scar tissue to build up over time. This can cause damage to the eyes, leaving you with ongoing symptoms like eye bulging, eye pain, eye pressure, double vision, and misaligned eyes, if not treated.

Having TED under control can help with flares. Flares can also occur after treatment. Learn about risk factors and potential triggers that can cause your TED to flare by using the Triggers and Flares Tool.

Early treatment decisions with your doctor are better, but treatment later in the course of TED may still help

The longer that TED goes untreated, the more likely it is for serious damage to happen to your eyes. While starting treatment in the acute phase is recommended, it may still help during the chronic phase.

Learn about a treatment option for TED.

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Get treatment for TED as early as possible to prevent further eye damage.