Thyroid Eye Disease ( TED ) is part of an autoimmune inflammatory disease that may cause periorbital edema, enlargement of the extraocular muscles, proptosis, lid retraction, optic neuropathy, and secondary increase of intraocular pressure. Limitation of ocular motility. Limitation of elevation is by far the most common defect of ocular motility, followed in order of frequency by limitation of horizontal and vertical gaze, caused by myopathy of the medial and superior rectus, respectively. The lateral rectus muscle is least commonly involved.

 Compression of the orbital apex by the enlarged extraocular muscles, especially the medial rectus muscle, may cause congestion of the optic nerve, axonal death, and decrease in visual acuity.

 An increase in intraocular pressure on upward gaze, suggesting tightness of the inferior rectus muscle, has been used for many years as a diagnostic tool in the early stages of the disease.

 Retraction of the upper lid is one of the many manifestations of Graves’ disease. It is usually caused by increased sympathetic innervation

MRI is of great value, especially in distinguishing endocrine myopathy from other pathologic changes of the orbit that restrict ocular motility.  The dramatic fusiform swelling ( Cocacola  Bottle Appearance ) of the extraocular muscles in a patient with endocrine myopathy is diagnostic

   Steroids are known to dramatically improve the congestive phase of the disease, they have, in our  experience, no significant effect on the chronic form of endocrine myopathy. We prefer to observe such patients for at least 6 months to establish the stationary nature of the disease. On many occasions we have noted that during this observation period other muscles  become involved so that a change in the surgical approach became necessary. Prismatic correction of vertical or horizontal deviations may be beneficial during this waiting period.  Systemic treatment directed at normalization of thyroid function in patients with hyperthyroidism.