Thyroid eye disease (TED) can cause inflammation and associated swelling of the muscles that allow the eye to move in different directions. Since each muscle does not swell the exact same amount, this may result in double vision or blurred vision. Evaluation and treatment of abnormal thyroid levels in your bloodstream by your primary physician or endocrinologist is important. Even when the thyroid function studies are normal, there may be eye findings related to the thyroid. Careful expert monitoring of any changes in vision, eye pressure, lid retraction or proptosis (bulging eyes) should be done on a routine basis in patients with known thyroid disease. In addition, your doctor will do a careful examination of the back of the eye to look for changes in the optic nerve. Visual field (peripheral vision) testing should also be done regularly. Surgical intervention may be suggested, including orbital decompression, eye muscle surgery, and/or eyelid surgery.