Thyroid eye disease is an autoimmune disease in which the cells that protect us from infections or other aggressive agents act defectively, attacking different organs or tissues of the body such as the thyroid and eyes. For example, with hyperthyroidism (excessive or out of control hormone production), inflammation of the eye may occur or there is an increase in pressure behind the eyes. This can lead to protruding eyes (proptosis), misalignment of the eyes (strabismus) and dysfunctions in the eyelids where, in severe cases, visual disturbances occur. Tobacco and stress are risk factors for developing hyperthyroidism. Treatment includes endocrine control, steroids or, in more severe cases, surgery.