Thyroid eye disease is a relatively rare condition, with an incidence of 2.9 to 16.0 cases per 100 000 population per year.1 The disease mainly affects women. Many patients experience distressing symptoms, and a few develop sight threatening complications. Patients are often young or middle aged and at the peak of their career. Most patients are very aware of their altered appearance. Sight loss can be prevented by appropriate management, yet it still occurs even in countries with advanced healthcare systems. This problem is largely due to delays in starting treatment, because health professionals are not always aware of the remarkable difference that treatment can make in restoring visual function and appearance.2 For example, treatment can reverse blindness and help a reclusive patient to become socially reintegrated. Referral to specialist centres is appropriate for all but the mildest cases.3 Thyroid eye disease is an autoimmune disorder, with associated thyroid autoimmunity always discernible.4 The presence of one or more shared autoantigens between the thyroid and the orbit may explain why retro-orbital tissues are affected.5 6 Extraocular muscles and retro-ocular connective tissue are infiltrated by lymphocytes, leading to activation of cytokine networks and inflammation and interstitial oedema of the extraocular muscles.7 8 Excess secretion of glycosaminoglycans by orbital fibroblasts seems to be an important contributor. The end result is expansion of the volume of extraocular muscles, retro-orbital fat, and connective tissue. Similar changes affect the eyelids and anterior periorbital tissues. Smoking increases the risk of developing thyroid eye disease by seven to eight fold.9 Apart from visible swelling and redness of the eyelids and conjunctiva, the other clinical features of thyroid eye disease can also be accounted for by the expansion of inflammatory soft tissue within the constraints of the rigid bony orbit. Anterior displacement of …