What are thyroid eye disorders?
Thyroid eye disorders are eye problems that may occur when the thyroid gland does not produce the normal amount of thyroid hormone.
The thyroid gland, which is located in the neck, produces hormones that regulate the body’s metabolism. Metabolism is the rate at which the body’s cells do their work. Your heart rate and the rate at which you burn calories reflect your metabolism. When your metabolism is not normal, eye problems may develop.
How do thyroid problems occur?
The exact cause of thyroid problems is not known. Possible causes include:
- a problem with the body’s immune system
- a growth on the thyroid gland
- a substance in your blood that causes the thyroid gland to produce too much hormone.
The problem usually affects people who are middle-aged and older. It is uncommon in people younger than 20. Thyroid eye problems are usually caused by hyperthyroidism (too much thyroid hormone). Rarely hypothyroidism (too little thyroid hormone) can affect your eyes.
What are the symptoms?
At first, thyroid problems may not produce many eye symptoms. Later, symptoms of thyroid eye disorders may include:
- Bulging eyes. The eyes are pushed forward, and you appear to stare. Bulging may occur in one or both eyes and in different amounts.
- A scratchy or gritty feeling in your eyes, especially when you wake up.
- Eyelids that do not close completely or cover less of the eye than normal when you are awake.
- Dry eye, which can occur when eyelids do not close normally. Constant dry eye can damage the cornea (the clear dome on the front of the eye).
- Tearing, which is your body’s response to dry eye.
- Lid lag, when the eyelid does not move down correctly when you look down.
Swelling, which can occur in many places, including:
- upper and lower eyelids
- tissues around your eyes
- the conjunctiva (clear tissue that lines the eyelids and covers the eye)
- blood vessels and other tissues inside the eye socket
- the optic nerve, which carries images to the brain
- the muscles that control the movement of the eye
- Increased sensitivity to light.
- Blurred vision, sometimes with reduced color vision.
- Double vision, which may occur as a result of limited eye movement.
- Limited eye movement because of swelling in the muscles around the eye. One eye may be more limited than the other. The direction of movement may be different for each eye.
How are they diagnosed?
Bellotte MD will look at how much your eye bulges out. He or she may press gently on your eye through the eyelid to see how firm it is. They will also look at the inside of your eye through an ophthalmoscope to see if there is any swelling or inflammation. They will then ask you to look in all directions to check your eye muscles, and check your color vision and pupils to see if your optic nerve has been damaged by the swelling of your eye muscles.
Various lab tests may be needed, including tests for:
- an infection caused by bacteria
- hormone levels
- thyroid function
- A test showing normal thyroid levels does not rule out thyroid disorders. You may still have eye problems that need treatment.
Drs. Bellotte may perform an ultrasound, a CT scan, or an MRI, which provide images of the inside of your eyes and eye sockets. These tests may show what is causing your symptoms.
How are they treated?
Thyroid eye disorders can be treated in a variety of ways. Medicines that may help include:
- drugs to regulate the production of thyroid hormones
- steroids to reduce inflammation and swelling
- a mild diuretic to reduce swelling
- artificial tears to keep the eyes wet
Surgery can be performed for various reasons. These include:
- changing the shape of eyelids so they close better
- changing the shape of eye sockets in the skull to provide room for swollen tissues
- removing the thyroid gland to cure hyperthyroidism
- altering the muscles, to relieve double vision.
- Some surgery, particularly that to improve your appearance, should be done only after treatment has reduced most of your symptoms.
Other measures that may help include:
- raising the head of your bed, which may help reduce the amount of fluid around your eyes
- taping your eyes shut at night to keep them moist
- wearing prism glasses to correct double vision
- having radiation treatments to reduce the size of the thyroid gland
- radiation treatments to reduce inflammation of the eye muscles
Some thyroid problems cannot be cured, such as a disorder called Graves’ disease. Often, thyroid problems can be well controlled and do not affect your eyes.
How long do the effects last?
Some of the effects last as long as hyperthyroidism exists. For example, 8 weeks of antithyroid medicine reduces many of the problems of Graves’ disease. Other drugs may take 6 months to 1 year to regulate your level of thyroid hormones.
Some symptoms, such as tearing and a scratchy feeling in your eyes, can be relieved by using medicine for a few days. Steroids can reduce swelling and inflammation in a few days to a few weeks. Problems that can be treated by surgery usually do not return if the surgery is done after the hyperthyroidism is under control.
Occasionally, eye problems appear, continue, or worsen after treatment for thyroid disorders is underway. Be sure that you have regular checkups so Bellotte MD can find out about any problems you have. Some thyroid eye disorders can lead to blindness if not treated.
How can they be prevented?
Usually thyroid problems can’t be prevented. However, serious problems with your eyes and blindness can be prevented by early diagnosis and treatment. Have regular checkups, and contact Bellotte MD at West Boca Eye Center if you develop any symptoms that concern you.