Thyroid eye disease is a rare disease characterized by inflammation in the tissues around the eyes and especially in the eye muscles, eyelids, lacrimal glands and fatty tissues in the back of the eye. Eyelid disease is an autoimmune disease, in which the immune system attacks the tissue surrounding the eye and causes inflammation in the area. In most patients, the same condition also affects the thyroid gland, and as a result they are at increased risk of developing another disease called “Graves”, which causes an overactive thyroid gland. However, in some situations, ocular thyroid disease appears precisely in people with hypothyroidism.
In the active phase of the disease, progressive inflammation and changes in the eye tissues occur. In some cases there is swelling, double vision and protrusion of the eyeballs (eyes that are “pushed forward”). The active phase can last between six months and two years, and then comes a phase where the progression of the disease stops. Cosmetic changes and significant disability can develop in some people, and in particularly severe situations loss of vision may occur.
What causes the disease?
Ocular thyroid disease is an autoimmune disorder, meaning a disorder in which the immune system mistakenly attacks healthy tissue instead of a foreign body or infectious source. In Graves’ disease, the immune system creates an abnormal antibody that also affects the cells surrounding the eyes, apparently because they contain proteins that are similar to those of the thyroid gland. The mechanism of the disease is related to the secretion of inflammatory substances.
What are the signs and symptoms of the disease?
The signs and symptoms of the disease can vary greatly from person to person, and the duration of the disorder is also not constant: in some people, the disease will remain stable for an extended period, while others will experience episodes of exacerbations and remissions over time. Initial symptoms include redness, irritation, dryness and pain when moving the eyes and eyelids. Eyelid retraction is also common when the upper eyelid is positioned too high or the lower eyelid is too low. The most significant external symptom may be the bulging of the eyeballs, as a result of the appearance of swelling in the muscles that control eye movements and the tissues behind the eye, which may appear as a glare. Other symptoms include blurred vision, double vision, strabismus, bleeding and tearing, along with sensitivity to light and difficulty moving the eyeball. Progressive swelling can even cause headaches, and in severe cases nerve damage and vision loss can develop.
Who is at risk of developing the disease?
Thyroid disease affects more women than men, but men tend to have more severe disease and the disorder is more common in middle age. There is a genetic component to the disorder, so people with an affected family member are at higher risk of developing it. People with other disorders associated with immune system dysfunction, such as juvenile diabetes or rheumatoid arthritis, also have an increased risk of getting sick. Also, pregnancy, smoking and treatment with radioactive iodine (for example as a treatment for overactivity of the thyroid gland) are risk factors for the disease.
The ways of treating the disease
Smoking causes worsening of symptoms and is strictly prohibited! Quitting smoking may bring about a significant benefit in the severity of symptoms.
The treatment of the disease usually occurs in two stages. The first stage includes treatment of the active eye disease and requires careful monitoring until the disease stabilizes. The treatment at this stage is focused on maintaining vision and the integrity of the cornea as well as double vision. Most patients experience relief from dry eyes when using artificial tears throughout the day and gels or ointments at night. Some also use eye covers at night. A disease with significant inflammatory activity is mainly treated with steroids to control the thickening of the eye muscle tissues.
Today there is a biological treatment that is specific to the disease and is approved by the FDA and is also used in Israel. This treatment is given by infusion and is based on an antibody of human origin that stops the secretion of the substances that cause inflammation in the tissues and is mainly given to patients who do not respond to steroids. In certain situations there is a need for surgery, to relieve the pressure on the optic nerve or to increase the volume of the eye socket. The treatment in the remission phase involves correcting permanent changes caused to the eye.