Thyroid Eye Disease

Autoimmune disease caused by the activation of orbital fibroblasts by autoantibodies directed against thyroid receptors type two hypersensitivity.

Aetiology

  • 90% of cases associated with Graves disease
  • About 10% of patients with TED have either a normal-functioning (euthyroid) or under-functioning thyroid (gypothyroidism e.g. Hashimoto's thyroiditis

Pathophysiology

  • Characterized by enlargement of the extraocular muscles, fatty and connective tissue volume
  • Orbital fibroblasts are activated by Graves' disease-related autoantibodies, leading to an inflammatory response which results in swelling, extraocular muscle enlargement and orbital fat expansion

Stages of TED

  1. Soft tissue involvement
    1. Sympoms - grittiness, photophobia, lacrimation
    2. Signs - hyperaemia, chemosis, periorbital swelling
  1. Lid retraction
  1. Proptosis
    1. Could lead to exposure keratopathy → corneal ulceration
  1. Optic neuropathy
    1. Compression of the optic nerve or its blood supply at the orbital apex
    2. Reduced vision and colour vision, RAPD
  1. Restrictive myopathy (inflammation and fibrosis)

Clinical presentation

  • Thyroid eye disease is the most common cause of unilateral and bilateral proptosis
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