Ocular manifestations of systemic disease: Thyroid eye disease

Question 1

Pathophysiology of what happens in thyroid eye disease

Answer 1

TSH-R Ab can activate T cells in the retro-orbital space
→ T cells produces interferon gamma and tumour necrotic factor alpha
→ fibroblasts will be stimulated in the retro-orbital space
→ increase in glycose amino glycans stimulated
→ GAGs are hyperosmolar and pulls a lot of water into the muscle tissue and tissue around the adipose
→ GAGs increase number of adipocytes behind the eye
→ swelling + increase orbital pressure
=> exophthalmos/proptosis

Question 2

Symptoms of thyroid eye disease

Answer 2

Binocular diplopia
Lid swelling
Staring gaze
Pain, tightness

Question 3

Signs of thyroid eye disease

Answer 3

• Peri-orbital/lid swelling
• Chemosis (Conjunctival edema)
• Conjunctival hyperemia/injection (Near medial and lateral rectus)
• Lid retraction
• Lid lag
• Exophthalmos/proptosis
• Ophthalmoplegia/Restricted EOM (binocular diplopia (especially on downward gaze))
• Corneal ulceration if presence of lagophthalmos
• ↓ vision, ↓ colour vision, RAPD, red desaturation in compressive optic neuropathy

Question 4

Order of muscles affected in ophthalmoplegia in thyroid eye disease

Answer 4

Most commonly affected muscles: inferior rectus > medial rectus > superior rectus > lateral rectus

Question 5

Investigations for thyroid eye disease

Answer 5

Bloods
- Thyroid function test (free T4, TSH)
- Thyroid Receptor Antibodies (TRAb)

Imaging
- CT orbits
- MRI orbits

Question 6

Imaging findings in thyroid eye disease

Answer 6

• Bilateral proptosis
• Coke bottle sign: swelling of muscle belly of EOM sparing the tendon (bilateral medial recti muscle)
• Apical crowding and congestion of orbital apex
• Tenting of optic nerve bilaterally
• Re-modelling of sphenoid bone

Question 7

Sight threatening complications of thyroid eye disease

Answer 7

Compressive neuropathy
Open angled glaucoma
Exposure keratitis

Question 8

Management ladder of thyroid eye disease

Answer 8

• Conservative
• Medical
• Radiotherapy (if medical fails)
• Surgical
• Rehabilitative (prism glasses)

Question 9

Conservative management of thyroid eye disease

Answer 9

• Topical Lubricants
• Elevate head to 30 degrees when sleeping
• Smoking cessation
• Eye patch/ Lid; Taping eyes in sleep (lagophthalmos)

Question 10

Medical management of thyroid eye disease

Answer 10

• Disease Control: Carbimazole
  + Co-management with endocrinologist to optimize thyroid control and modify risk factors
• Steroids (IV methylprednisolone) for active disease
• Anti-Glaucoma Eye drops

Question 11

Surgical management of thyroid eye disease

Answer 11

• Orbital Decompression
• Strabismus/Squint Surgery (if unresolved diplopia to correct misalignment of eye)
• Lid Surgery - Tarsorrhaphy