Graves’ disease is an autoimmune disorder in which the immune system attacks the thyroid gland and causes it to make too much thyroid hormone, a condition called hyperthyroidism. Thyroid hormones control body metabolism, and too much can cause unexpected weight loss, fatigue, increased heart rate, and feelings of irritability and anxiety. The immune system may also attack the muscles and tissues around and behind the eyes, causing thyroid eye disease (TED). Symptoms of TED may include bulging eyes, dry, gritty and irritated eyes, red eyes, watery eyes, puffy eyes, sensitivity to light, pain or aching, and blurred or double vision. Up to one-half of people with Graves’ disease develop TED, which can be one of the first signs of Graves’ disease. However, TED and Graves’ disease are two different conditions, and each require their own treatment plans.