Thyroid-associated ophthalmopathy (commonly known as hyperthyroidism) is the most common cause of proptosis in adults. In mild cases, there is only a slight recession of the eyelid, while in severe cases the eye is highly protruding with compressive optic neuropathy or exposure keratitis. It is difficult to diagnose in early stages and typical in later stages of ocular disease. I. Epidemiology and etiology Thyroid-associated ophthalmopathy is mostly adult-onset and rare in children; the number of female patients is 5 to 8 times higher than that of male. Thyroid-associated ophthalmopathy is an autoimmune inflammatory disease involving the orbital tissues, and its etiology is unknown. Clinical features Thyroid-associated ophthalmopathy (hyperthyroid proptosis) often begins with non-specific irritation of the eye, followed by eyelid recession, late drop, swelling, and protrusion of the eyeball. Patients may feel that the condition worsens in the morning and decreases during the day. Most patients have a history of abnormal thyroid function, but about 30% of patients start with normal thyroid function. Initial signs are very nonspecific and difficult to diagnose. Eyelid recession and late drop are early signs that help in the diagnosis. As the disease progresses, eyelid edema, protrusion of the eyeball, dyskinesia, and diplopia become progressively more pronounced. Late onset of compressive optic neuropathy leads to loss of vision and severe corneal exposure. Eyelid retraction Eyelid retraction Conjunctival congestion, edema Eyeball protrusion Compressive optic neuropathy III. Imaging Imaging (CT or MRI) of thyroid-related ophthalmopathy (hyperthyroidism proptosis) may show hypertrophy of the extraocular muscle belly and less involvement of the tendons. The inferior rectus muscle is most commonly involved, followed by the internal rectus, superior rectus, and rarely the external rectus. Imaging is not necessary for diagnosis, but is helpful in the diagnosis of atypical cases and in the evaluation of optic nerve compression to facilitate a full understanding of the condition before and after surgery and radiotherapy. IV. Course The course and severity of the disease varies widely in patients with thyroid-related ophthalmopathy (hyperthyroid proptosis). It can be a mild inflammation lasting several months with no sequelae, or it can be severe and severe, leading to high proptosis, diplopia and loss of vision over months or years. Patients who smoke often have a longer and more severe course of disease. Treatment with radioactive iodine in patients with hyperthyroidism can aggravate the condition of thyroid-related ophthalmopathy (hyperthyroid proptosis). Treatment The early (active) treatment of hyperthyroidism is mainly to control inflammation to reduce scar formation and avoid severe progression of the disease. Systemic application of hormones can reduce the inflammatory response, but long-term use can have side effects; therefore, short-term (high-dose) treatment is advocated. Orbital radiotherapy can effectively control the development of lesions but cannot reverse existing lesions, and its clinical application is controversial. Immunomodulators (rituximab) have been attempted to block the autoimmune course of thyroid-related ophthalmopathy (hyperthyroidism and proptosis). Immunosuppressive agents (cyclophosphamide) may be tried in thyroid-related ophthalmopathy (hyperthyroidism) where treatment has failed. The later (stable) stages of treatment for thyroid-related ophthalmopathy (hyperthyroid proptosis) are based on surgical correction, including ocular proptosis, diplopia, and eyelid deformity. Surgical approaches include orbital decompression and surgery of the eye muscles and eyelids. In severe cases with compressive optic neuropathy or corneal exposure, orbital decompression surgery should be performed urgently. Prognosis The prognosis for patients with thyroid-related ophthalmopathy (hyperthyroid proptosis) is generally good. However, some patients may require multiple surgical procedures over several years. Patients with severe disease often require longer treatment cycles.