Pathology

Stimulating TSH receptor antibodies are inevitably found.

Fibroblastic deposition of glycosaminoglycans and lymphocytic infiltration into the extraocular muscles and retrobulbar connective tissue produces retrobulbar oedema. This is followed by fibrosis with restricted movement as the muscles become tethered to the surrounding structures.

Consequently:

• the eye is pushed forwards and there is axial proptosis The cornea may become exposed with drying, irritation and later ulceration
• extraocular muscle movement is impaired
• increasing pressure is exerted on the optic nerve with loss of acuity and eventually, atrophy
• venous drainage from the orbit is impaired resulting in conjunctival and periorbital oedema, and conjunctival injection