What is the main pathophysiology of Thyroid Eye Disease?

• A. ACH antibodies target NMJ
• B. TSH receptor antibodies target EOMs and orbital tissue
• C. PNS demyelinating condition
• D. Thyroid secreting tumor

Answer: (D)

Thyroid Eye Disease is driven by an autoimmune process where antibodies against the TSH receptor stimulate receptors on orbital fibroblasts and the extraocular muscles. This activation triggers inflammatory signaling, leading to cytokine release, production of glycosaminoglycans, adipogenesis, and edema within the orbit. The result is swelling and enlargement of the extraocular muscles and other orbital tissues, causing proptosis, diplopia, and sometimes impaired eye movement. This mechanism links the eye disease to Graves’ hyperthyroidism, since the same TSH receptor antibodies drive both conditions. It is not caused by antibodies at the neuromuscular junction, a peripheral nerve demyelinating process, or by a thyroid tumor secreting hormone; the orbital disease specifically reflects autoimmune targeting of TSH receptors in orbital tissues.