Thyroid eye disease

• Thyroid eye disease (TED) is an autoimmune condition resulting in inflammation and swelling of the extraocular muscles, fatty tissue and connective tissue within the orbit.
• It is the most common cause of unilateral and bilateral exophthalmos in adults and more common in females
• Aetiology:

  • Commonly occurs in patient's with Graves' disease
  • Can present in euthyroid or hypothyroid patients
  • In most patients, eye disease and thyroid issues evolve within 1.5 years of each other
• Pathophysiology:

  • Closely correlating with Graves disease, patients with TED have been found to have elevated levels of antibodies against TSH receptors - expressed in orbital fat and connective tissue
• Risk factors for thyroid eye disease include:

  • Smoking
  • Previous radioiodine therapy
  • Men have more severe disease (more common in females)
• Symptoms:

  • Excessive watering
  • 'Gritty' sensation
  • Photophobia
  • Eye pain
  • Other important symptoms to ask - red eye, blurred vision (incomplete eyelid closure) and sensation of pressure
  • May also present with systemic signs of thyroid disease
• Clinical exam:

  • Eyelid retraction - Dalrymple's sign
  • Proptosis
  • Lid lag - Von Graefe's sign
  • Lid oedema
  • Diplopia - restriction of extraocular muscles (most commonly inferior rectus - unable to look up)
  • Incomplete eyelid closure
• Compressive optic neuropathy:

  • In a small portion of patients, the enlarged muscles and fat can press on the optic nerve
  • Sight - threatening complication
  • Reduced visual acuity
  • Decreased colour vision
  • RAPD (may be absent if both eyes affected)
  • Optic nerve can be normal, oedematous or pale
  • Treated with urgent IV methylprednisolone
• Incomplete eyelid closure can lead to corneal exposure and ulceration
• Investigations:

  • TFTs
  • Antibody testing
  • USS/CT/MRI or orbits
• Smoking cessation advice should be given to reduce the risk of further exacerbations. If patients are reporting symptoms from corneal exposure, artificial tears and tapes can be used to provide relief.
• Some patients may require surgery, such as orbital decompression and lid surgery, if there is significant corneal exposure or progressing proptosis
• Complications:

  • Loss of sight secondary to compressive optic neuropathy
  • Globe subluxation - eye 'popping' out
  • Gaze abnormalities
  • Raised intraocular pressure leading to glaucoma