Thyroid Eye Disease (TED)
Thyroid eye disease, a.k.a. TED or thyroid orbitopathy, is an autoimmune condition. The body’s immune system produces inflammation that causes enlargement of the tissues in the eye socket (also called the orbit), including the muscles that move the eye. This can result in bulging of the eyes, retraction of the eyelids (making them more wide open), double vision, decreased vision, and eye irritation.
The eye condition is associated with abnormalities in thyroid gland function. When overactive, the thyroid condition is called Graves’ disease, and when underactive, it is called Hashimoto’s thyroiditis. Signs of an overactive thyroid include tremors, shakes, weight loss, rapid heartbeat or palpitations, nervousness, and sensitivity to heat. Less commonly the attack on the thyroid gland leads to low thyroid production with weight gain, dry skin, and fatigue. Occasionally, the thyroid levels may be normal, but antibodies in the blood that can be identified as attacking thyroid tissue.
The eye findings of thyroid eye disease may be independent of treatment of thyroid abnormalities and may not go away or get better even if the thyroid is “controlled.” These symptoms may also be present even when your thyroid has no apparent problems.
How or why the immune system attacks the orbital tissues, particularly the eye muscles, is not fully understood. The result is enlargement of the muscles and the fat that normally cushions the eye and other important structures in the orbit. As the eye socket tissues get larger, 3 things may happen:
- the eyeball gets pushed forward
- the muscles themselves become stiff and the eye may not move normally and/or
- the muscles may press on the optic nerve, leading to visual loss.
The eye muscles
There are 6 muscles that move the eye. These muscles originate behind the eye at the very back of the eye socket and attach near the front part of the eyeball. The muscles cannot be seen on the surface as they are covered by a thin layer of tissue (the conjunctiva) but may become visible as the blood vessels over their front portion become very prominent.
In thyroid eye disease, the eye socket fat and the eye muscles become inflaned and swollen. With eye muscle enlargement, the eyeball is pushed forward and the eyes appear more prominent and wide open. In addition, the muscles become stiff and the upper eyelid tends to pull up (retract) away from the colored portion of the eye, making the white part of the eye more visible. The eyes may become red due to difficulty closing as well as increased prominence of the blood vessels. This often results in double vision with one image seen vertically one on top of the other, side by side, or diagnonally.
The optic nerve
The optic nerve transmits information from the eye to the brain. Damage to the optic nerve results in decreased vision. If the muscles get large enough, they may press on the optic nerve causing damage to the nerve. If the optic nerve is compressed, the patient may experience blurred, dark or dim vision. Fortunately, this only occurs in about 5% of the patients with thyroid eye disease and may be reversible if the pressure on the optic nerve is relieved in a timely fashion.
It is important for Dr. Banik to sort out whether or not there is any evidence of abnormal optic nerve function. This is detected by carefully checking vision, color vision, pupil reaction, visual fields (a peripheral vision test), the appearance of the optic nerve in the back of the eye.
Common symptoms of thyroid eye disease, or TED, include:
- Blurred or distorted vision
- Dry eyes
- Eyelid retraction (the eyelid gets pulled away from the colored part of the eye, exposing more of the white part)
- Eyelid or eye swelling
- Double vision due to eye misalignment
- Eye tightness or ache, worse with moving the eyes
- Protrusion, or bulging of the eye
- Pressure or mild pain behind the eye
- Dimming or darkening of vision
Sometimes patients will only be aware of symptoms related to thyroid overaction (nervousness, tremors, rapid or irregular heart beat, increased sweating and intolerance to heat, weight loss, and diarrhea) or underaction (fatigue, weight gain, constipation, thickening of the skin). These symptoms may precede eye symptoms by months or even years.
Thyroid eye disease, like other autoimmune diseases, often comes and goes on its own. There is frequently only one inflammatory episode that comes on over a short period of time and lasts for about 1 to 2 years. This is called the “active phase”. The effects on your eyes may persist for years or even permanently, especially if untreated. This is referred to as the “inactive phase”.
Smoking will exacerbate the severity of eye involvement in thyroid eye disease and thus, quitting tobacco use is recommended.
Even when the inflammation resolves, the eyes usually do not go back to what they looked like beforehand. There may be some reduction of the prominence of the eye and the eyelid may come down a little, but patients may still require treatment to reach a comfortable state. If eye movements are significantly involved and there is double vision, this will often not return to normal. Fortunately, permanent damage to vision from optic nerve involvement is rare (5%) and often reversible is caught early.
Treatment is aimed at improving the symptoms and severity of eye socket involvement to prevent long-term problems. Avoiding tobacco smoking and controlling the thyroid function with medications or other methods is recommended to decrease severity of eye involvement. Treatment is most effective early in the active phase.
In this stage, irritation and foreign body sensation from surface dryness may improve with artificial tears (preferably preservative free if using more than 4 times daily) and the use of lubricating ophthalmic ointment at night. If the eyelids are not closing completely, they may be taped closed at night. Humidifiers and moisture chamber goggles/glasses may also be used to reduce evaporation of tears and improve dry eye symptoms. Non-steroidal anti-inflammatory medications (such as diclofenac, ibuprofen, naproxen, etc.) may be used to manage pain or discomfort from orbital inflammation. Oftentimes, Dr. Banik may recommend specific supplements or a customized diet regimen.
Moderate to severe TED
With increased prominence of the eye and opening of the eyelids, symptoms of exposure of the eye surface may be too severe to be treated with lubricating drops and ointment.
Double vision from misalignment of the eyes may lead to significant decrease in quality of life. Treatment of these signs and symptoms will depend on whether the patient is in the active or inactive phase. Surgery for treating thyroid eye disease is usually performed in a specific order, preferably in the inactive phase.
Double vision may be addressed with wearing temporary prism glasses, which shift the images to allow single vision. If the images are too far apart to address with prisms, covering one eye may be necessary to relieve double vision. Either eye may be covered.
Steroid treatment is used to treat the inflammation in the active phase in moderate to severe eye involvement from thyroid eye disease. Reasons to get steroid treatment include severe double vision, severe exposure of the eye surface from prominence of the eye with inability to close the eye, or if the optic nerve becomes involved. During this treatment, side effects need to be monitored and treated.
An alternative treatment to steroids includes low dose radiation (X-ray therapy) to the orbit. This treatment has been shown in some studies to be effective in the active phase.
Medications that suppress the immune system other than steroids may also be used, but these have not been definitely proven to work and are given on a case-by-case basis to people who are unable to tolerate steroid treatment.
If medical treatments fail to improve symptoms, surgery may be necessary in the active phase. Eyelid surgery may be required to help partially close the lids to treat exposure of the eye surface. Orbital decompression surgery during the active phase may also be required to create more room in the eye socket for the expanding tissues, but this is usually reserved for more severe eye involvement with optic nerve compression causing damage to the vision. One of the side effects of surgical decompression is that it may affect eye movements, potentially producing or worsening double vision.
During your visit, Dr. Banik will spend the time to review all the options for treatment of thyroid eye disease which are best for you.
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