Hyperthyroidism can cause swelling of the tissue in the eye socket (orbit). Symptoms of this condition, called Graves' orbitopathy or ocular Graves' disease, include:
- The eye being pushed forward, creating a wide-eyed or bulging stare. This is known as exophthalmos.
- Pain in the eyes when looking up or down
- Dryness and itching in the eyes
- Double vision
- Temporary or permanent loss of vision in severe cases
Eye symptoms usually occur at the same time as hyperthyroidism, but they may start before or after the symptoms of hyperthyroidism begin. Most patients with thyroid abnormalities will not be affected by eye disease and some patients only mildly so. Vision loss due to pressure on the optic nerve is the most severe form of the disease. Fortunately, this condition is rare, affecting less than 5% of patients with Graves' orbitopathy. Treatment with prednisone, radiotherapy, and/or surgery may be required to restore vision. Although the chance of having ocular Graves' disease is higher and more severe in smokers, there is no way to predict which thyroid patients will be affected. In addition, successful treatment of hyperthyroidism does not guarantee that the eye disease will improve although surgery seems to have better results than RAI ablation in improving eye disease. Once inflamed, the eye disease may remain active from several months to as long as three years. While rare, recurrence of the eye disease can happen and may be asociated with poor control of thyroid hormone levels.
Overall, it is important to keep in mind that eye disease associated with Graves' disease will only improve gradually. The management of ocular Graves' disease includes both medical and surgical therapy and our ophthalmology experts in the Thyroid Center can help plan the appropriate treatment.
Medical Treatment of Thyroid Eye Disease
Early eye symptoms, such as dryness, redness, itching, swelling of the lids and inability to wear contact lenses, are usually mild. Some patients find these symptoms to be particularly irritating at night and during exposure to air conditioning, hot air heating, and wind. A few patients will develop double vision (diplopia), which is the result of asymmetric inflammation of the muscles that control eye movement. Many patients develop mild symptoms that are often misdiagnosed as an "ocular allergy." Therefore, Graves' disease patients should be followed by an ophthalmologist familiar with the condition and available treatments. Patients with mild symptoms can often be successfully treated with frequent use of lubricating eye drops and wearing eye covers at night. Humidification of room air can prevent drying of the eyes, and wrap-around polarizing sunglasses can also help relieve glare. Diplopia can be improved by wearing special prism lenses while awaiting either spontaneous improvement or surgical correction. Temporary plastic prisms may be put on a regular set of eyeglasses and changed as needed. Prednisone, a steroid medication, may be taken in pill form to provide temporary relief from pain, swelling and redness, although side effects of the medication may limit its use.
Surgical Management of Thyroid Eye Disease
If ocular Graves' disease does not improve or if it gets worse despite treatment, surgery may be required. Retracted and puffy eyelids can change a person's appearance and increase the risk of the cornea drying. Corrective eyelid surgery can improve this problem through loosening of the eyelid muscles, as well as removal of scar tissue, excess fatty tissue and skin to place the eyelids into a more normal position. Surgery may also be necessary to correct diplopia when this problem has not improved either spontaneously or with prism lenses. Surgery to correct diploplia involves disconnecting and repositioning the muscles that control eye movement to improve ocular alignment and minimize double-vision.
The enlargement of tissue behind the eye may sometimes cause significant bulging of the eye (exophthalmos), which produces the characteristic wide-eyed stare seen in ocular Graves' disease. Swelling in the orbit may also contribute to vision loss as pressure increases on the optic nerve. Surgical procedures to reduce pressure on the optic nerve can improve vision and allow the eye to settle back to a more normal position. Orbital decompression is indicated in patients with significant exophthalmos, visual loss, or severe exposure of the corneas. Orbital decompression involves surgical removal of fat from behind the eyeball and may also involve removing some of the bone surrounding the eye socket.
For most patients, surgery is performed under general anesthesia and usually requires an overnight hospital stay.