The thyroid gland, located in the neck, produces thyroid hormone that helps regulate our metabolism. It may produce either too much thyroid hormone (hyperthyroidism) or too little (hypothyroidism). Another name for hyperthyroidism is Graves Disease. Hyperthyroidism can be associated with eye and vision problems.
Initially, the symptoms of hyperthyroidism are subtle. Fatigue, tiredness, and malaise may be the first symptoms. In addition, hyperthyroid patients may lose weight, have a fast heartbeat, be intolerant to heat, and have diarrhea. Their hair may become finer and they may lose hair. Hypothyroidism, in contrast, may result in weight gain, constipation and a slow heartbeat. A blood test can detect either hyperthyroidism or hypothyroidism.
With hyperthyroidism, initially the eyes will feel dry, gritty, and irritated. There can be a sense of pressure behind the eyes, but rarely pain. Several changes occur around the eye that result in a staring appearance. The eyelids swell and are drawn apart, and the eyes become red. The muscles behind the eye become swollen, pushing the eye forward (see our article on bulging eyes) and often limiting eye movement that causes double vision. If the muscles become very swollen, they can push on the optic nerve, which may cause vision loss.
As the disease progresses, the symptoms mentioned above commonly come and go from day to day, week to week, or month to month. However, over time (up to 36 months) the fluctuating symptoms will disappear but the startled appearance, double vision, and eyelid swelling may persist. It is impossible to predict which patients will spontaneously improve. Often hyperthyroidism affects each eye differently so the face may look imbalanced. Eye differences can also occur even when there are no blood findings to indicate hyperthyroidism.
Once an overactive thyroid gland is suspected, the thyroid function must be evaluated and appropriately treated by your primary physician or a physician specializing in thyroid abnormalities (endocrinologist). Eye symptoms may continue to progress even after treatment returns thyroid levels to normal. Therefore, any eye symptoms should be checked and followed by an eye doctor.
From a vision standpoint, hyperthyroidism is evaluated and treated differently depending on the stage of the disease – the first ‘active’ phase, where the eye symptoms change daily or weekly, or the second ‘stable’ phase, after approximately 36 months, when the symptoms have stabilized. Treatment is different during these two phases.
Treatment during the active phase of the eye disease focuses on reducing discomfort, avoiding double vision, and preserving sight. Discomfort may be improved by using artificial tears or ointments, elevating the head of the bed at night, using dark glasses and taping the eyelids closed at night. Occasionally, corticosteroids (prednisone) may be required to decrease the swelling but may produce their own side effects. Double vision is usually treated during the active phase by patching one eye or using prisms in glasses. Thyroid eye disease rarely causes vision loss. However, vision needs to be monitored by an ophthalmologist or optometrist. If necessary, corticosteroids, surgery, or radiation may be recommended.
Once the eyes stabilize, treatment is directed toward correcting unacceptable permanent changes. Surgery may be recommended to reduce protrusion of the eyes. Eye muscle surgery may improve double vision. Eyelid surgery may also be recommended to correct the startled appearance.
Thyroid eye disease may run a prolonged course and be emotionally stressful. A person’s appearance may change, causing stress in work and interpersonal relationships. Double vision may make walking or driving difficult or risky. Fortunately, the disease will stabilize. If the eyes do not improve acceptably on their own, surgery can help. However, patience is necessary during the active stage.