Thyroid eye disease, also known as Graves’ eye disease, is a problem that usually develops in people with an overactive thyroid caused by Graves’ disease. Grave’s disease is an autoimmune condition in which immune cells attack the thyroid gland. In response, the thyroid gland secretes an excess amount of thyroid hormone.
The thyroid gland enlarges while the excess hormones increase the body’s metabolism. This resultant hypermetabolic state is characterized by fast pulse and heartbeat, palpitations, profuse sweating, high blood pressure, irritability, fatigue, weight loss, heat intolerance, and loss of hair and alterations in hair quality. In the case of Graves’ eye disease, the immune system attacks the tissues around the vision and causes the eye muscles or fat to expand.
Eye muscles and connective tissues contain proteins that appear to the immune system as similar to those of the thyroid gland, which makes the eyes particularly sensitive to Grave’s disease. Those living with thyroid eye disease can experience symptoms ranging from mild to severe, though only 10-20% of patients are at risk for losing their eyesight.
When the immune system attacks the muscles and other ocular tissues in the eye socket, the swelling and scarring resulting from the inflammation causes symptoms such as redness, pain, puffiness, bulging of the eyes, dry eyes and irritation, occurring when the eyelids cannot close completely over bulging eyes.
Severe symptoms include increased pressure inside the eye socket, pressure-pain or deep headache, which worsens with eye movements, and decreased vision, when swollen tissues push on the optic nerve.
In the most severe cases, an ulcer can develop on the cornea, the clear covering of the eye, or the optic nerve can be damaged. A permanent loss of vision can result from either of these scenarios, if the eye is not treated appropriately.
Many patients with mild to moderate Graves’ eye disease will experience spontaneous improvement over the course of two to three years. However, severe cases do occur in 10% of patients. If your doctor suspects you have an Grave’s eye disease and therefore an overactive thyroid gland, your thyroid function must first be evaluated and treated. This may include medications to suppress the production of hormones by the thyroid gland, radioactive iodine to eliminate hormone-producing cells, and surgery to remove the thyroid tissue.
In most cases, replacement thyroid hormone is required following the natural course of the Graves' autoimmune attack on the thyroid gland or following effective treatment. It is important to note, however, that Graves' disease does not directly cause Graves' eye disease. Treatment of the thyroid gland, while important, will not improve thyroid eye disease. The two diseases run their separate courses and do not necessarily occur at the same time.
To address thyroid eye disease, treatment generally occurs in two phases. In phase one, the active eye disease is treated. This active period usually lasts two to three years and requires careful monitoring. During phase one, treatment focuses on preserving sight and the integrity of the cornea, as well as providing treatment for double vision.
During phase one, patients with dry eyes are treated using artificial tears throughout the day and gels or ointments at night. Some patients also use eye covers at night or tape their eyes shut to keep them from becoming dry if the eyelids do not close properly. In some cases, prednisone may be used for a limited time to treat acute swelling that causes double vision or loss of vision. However, prednisone should not be given for more than a few weeks at a time.
In patients who respond to prednisone, radiation therapy may also be offered to reduce swelling, double vision, and, in severe cases, loss of vision. While most patients get relief from their symptoms within two months of the radiation, it is only marginally effective and may cause ocular dryness. It also can only be used at most twice in a person's lifetime and bears a slight risk for inducing tumors. Surgical treatment may be used as well, most often to relieve optic neuropathy. It is also helpful in reducing congestion, redness, pain, and ocular exposure.
In January of 2020, the Food and Drug Administration (FDA) approved a drug by the name of Tepezza, currently the only medication approved to treat thyroid eye disease. It reduces eye swelling, bulging, and double vision, and patients reported that they also experienced less pain and redness during Tepezza treatment.
In most cases, during phase two - the remission phase - treatment lasts indefinitely. It involves correcting permanent changes that persist after the conditions of the active phase have stabilized. Treatment of these permanent changes may require surgery, either to correct double vision and reduce eyelid retraction or to return the eye to a normal position within the socket.
Whether you are in treatment phase one or two, it is important to continue monitoring your eye function on a continual basis. Scarring and visual loss that can only be detected by a professional can still occur, even if you don’t notice symptoms yourself.