Thyroid-associated orbitopathy is a syndrome of upper lid recession, lid drop, protrusion, diplopia, and ocular motility disorders due to abnormal thyroid function, along with generalized infiltrative skin lesions and goiter. So, what are the causes of thyroid-related orbitopathy? Common causes of thyroid-related orbital disease are as follows: 1. extraocular muscle edema, mononuclear inflammatory cell lymphocyte, plasma cell, mast cell infiltration, aminoglucan mucopolysaccharide deposition, fatty degeneration, which can damage the superior or inferior ophthalmic vein, venous reflux impairment, resulting in elevated surface scleral venous pressure, affecting the flow of anterior chamber water to the outside of the eye via schlemm’s canal and collecting duct, resulting in elevated intraocular pressure. Further development of glaucomatous optic nerve damage. In the late stage of orbital infiltrative lesions, due to fibrosis and contracture of the extraocular muscles, the eye gaze in a certain direction can cause a significant increase in IOP. When the eye is gazing upward, the upper rectus muscle contracts and the lower rectus muscle cannot relax accordingly, squeezing the eye and causing an increase in IOP. Therefore, attention should be paid to observe the IOP in different fields of vision. 3, the enlargement of the external muscle of the eye increases the orbital pressure, and in order to maintain the blood return to the central retinal vein in the eye, the intraocular pressure also increases. As thyroid-related orbital disease often causes protrusion of the eyeball, late regression of the upper lid, incomplete closure of the eyelid, and exposure of the cornea, causing exposure keratitis, when secondary to corneal infection, it can lead to adhesion of the anterior chamber angle tissue. 4, If the vortex vein is involved, so that the vortex vein reflux is blocked, it can cause uveal stasis and swelling, especially the ciliary body swelling forward, leading to narrowing and closing of the anterior chamber angle, secondary to angle-closure glaucoma. 5. Long-term elevated surface scleral venous pressure without timely treatment can reduce ocular perfusion pressure and ocular tissue ischemia, leading to iris redness and neovascular glaucoma. These are the causes of thyroid-associated orbital disease. In addition, thyroid-related orbital disease stops developing at a certain point and heals on its own. It can take as short as 1 to 2 years or as long as 10 years. Therefore, there is usually no need for any treatment.