Between June 1, 2006, and May 31, 2007, all patients who had developed ocular signs during the past 6 months and demonstrated active GO with a clinical activity score (CAS) of 4 or higher16 at the beginning of therapy and who underwent systemic corticosteroid therapy at Taipei Veterans General Hospital were prospectively recruited for the study. Before inclusion in the study, euthyroidism in all patients having GO was achieved by medication (antithyroid drugs only, including carbimazole, methimazole, and propylthiouracil, or combined with thyroxine sodium) for at least 6 months. None were treated with radioactive iodine. The diagnosis of GO was based on the criteria proposed by Bartley and Gorman.17 Computed tomography of the orbit and Hertel exophthalmometry were performed to help confirm the diagnosis of GO. Control subjects were recruited from age-matched and sex-matched healthy persons who were enrolled when they attended their routine physical examinations. Exclusion criteria were pregnancy, alcohol drinking, any ocular diseases other than GO, regular drug ingestion or antioxidant use, and GO with a history of surgical decompression, systemic corticosteroid therapy, or radiation therapy, as well as individuals with chronic or acute disease such as cancer, hypertension, hyperlipidemia, diabetes mellitus, and diseases of the lung, liver, or kidney or other endocrine, immunologic, or inflammatory disorders. The study was approved by the institutional review board of Taipei Veterans General Hospital, and patients gave informed consent for their participation.