This study is being done to investigate the effects (good and bad) of Rituximab for the treatment of an autoimmune eye disease called Graves' ophthalmopathy. This disease has proven to be difficult to treat. Rituximab is a monoclonal antibody that depletes a line of cells involved in the autoimmune response. The study hypotheses is that rituximab is effective in the treatment of patients with moderate to severe active Graves' ophthalmopathy.