Optic Neuritis

Question 1

What are some causes of optic neuritis?

Answer 1

• MS - acute demyelinating ON (ADON)
• GCA - ischaemic
• Diabetes
• Infections - Syphilis, TB, mycoplasma.
• Autoimmune (SLE, sarcoidosis)
• B12 Deficiency
• Drugs - amiodarone, cytotoxics.

Question 2

What is the most common type of optic neuritis (In regions where MS is more common)?

Answer 2

Acute Demyelinating Optic Neuritis (ADON)

Question 3

What is the classic triad features of optic neuritis?

Answer 3

1. Eye pain
2. Worsening vision
3. Impaired colour vision (Dyschromatopsia)

Question 4

What are some signs of optic neuritis?

Answer 4

• Decreased pupillary light reaction in the affected eye: A relative afferent pupillary defect (RAPD)
• Central scotoma
• Flashes
• Uhthoff’s phenomenom - worsening symptoms with increased temperature.

Question 5

What is the management of optic neuritis?

Answer 5

• Refer to opthalmologist as an emergency as other causes of unilateral blindness need to be excluded.
• High dose steroids
• Recorvery usually takes 4-6 weeks

Question 6

What investigations should be done?

Answer 6

An MRI to exclude MS.

If > 3 white matter lesions, 5 year risk of developing MS is 50%

Question 7

Retrobulbar neuritis & Papillitis are subtypes of optic neuritis. Describe briefly the pathology occuring in them.

Answer 7

• In retrobulbar neuritis, the posterior aspect of the optic nerve is affected.
  
  • (No swollen optic disc)
• In papillitis, the optic nerve head is affected
  
  • Swollen optic disc