Autoimmune responses to the thyrotropin receptor result in Graves' Disease. Evidence is accumulating that the same antigen is implicated in thyroid-associated orbitopathy (TAO) or thyroid eye disease. Progress in the establishment of receptor induced animal models has led to the development of a murine model in which the orbits of affected mice bear striking resemblance to human TAO with disruption of muscle fibres by oedema, accumulation of adipose tissue and infiltration by cells of the immune system.