Thyroid eye disease (TED) is an eye condition in which the eye muscles and fatty tissue behind the eye become inflamed. This can cause the eyes to be pushed forward (‘staring’ or ‘bulging’ eyes) and the eyes and eyelids to become swollen and red. In some cases, there is swelling and stiffness of the muscles that move the eyes so that the eyes are no longer in line with each other; this can cause double vision. Rarely TED can cause blindness from pressure on the nerve at the back of the eye or ulcers forming on the front of the eyes.
TED is an autoimmune disease. It occurs when the body’s immune system attacks the back of the eye and causes inflammation. It is mainly associated with an over-active thyroid due to Graves’ disease, although it does sometimes occur in people with an under-active or normally functioning thyroid. Graves’ disease is the most common cause of an over-active thyroid (hyperthyroidism) in the UK. TED is also known as Graves’ orbitopathy (GO).
Overall, about a quarter of people with Graves’ disease develop TED either before, during, or after their thyroid disorder is diagnosed. In most cases the eye disease is mild. If you have no features of TED by the time the Graves’ disease is diagnosed and you are a non-smoker or ex-smoker then your chance of developing TED is less than one in ten. But if you smoke your chance of developing TED is doubled. If you are a heavy smoker, the chances of developing TED are increased eight times compared to non-smokers.
These are the most common symptoms. See your doctor if you have any of the following:
If you have puffy eyelids and skin around and under the eyes and you have a severely under-active thyroid, this is probably not TED. It should improve once you are adequately treated with levothyroxine.
TED can sometimes be difficult to diagnose and patients may be treated for conjunctivitis, allergy or hay-fever for months before the diagnosis is made. The clues that the diagnosis may be TED rather than the above are: