Optic Neuritis

Question 1

What is Optic Neuritis?

Answer 1

Demyelination of the optic nerve and loss of vision in one eye.

Question 2

Aetiology of Optic Neuritis (8).

Answer 2

1. Multiple Sclerosis (Main).
2. Sarcoidosis.
3. SLE.
4. Diabetes.
5. Syphilis.
6. Measles.
7. Mumps.
8. Lyme disease.

Question 3

Epidemiology of Optic Neuritis (2).

Answer 3

Commoner in :-

1. Women.
2. High Latitude Dwellers.

Question 4

Pathophysiology of Optic Neuritis.

Answer 4

Inflammatory process leads to activation of T-Lymphocytes that can cross the BBB and cause a hypersensitivity reaction to neuronal structures.

Question 5

Clinical Features of Optic Neuritis (5).

Answer 5

1. Unilateral Reduced Vision (Hours-Days).
2. Central Scotoma (Enlarged Blind Spot).
3. Ophthalmoplegia.
4. Impaired Colour Vision and ‘Red Desaturation’.
5. RAPD.

Question 6

Investigations of Optic Neuritis (2).

Answer 6

1. Urgent Referral to Ophthalmology.

2. Diagnosis - Clinical : Triad of (i) Visual Loss; (ii) Periocular Pain; (iii) Dyschromatopsia.

Question 7

Management of Optic Neuritis (2).

Answer 7

1. 1st line - IV Methylprednisolone.

2. Oral Prednisolone alone is contraindicated due to increased risk of second episode.

Question 8

Prognosis of Optic Neuritis (4).

Answer 8

1. Recovery takes 2-6 weeks.
2. 50% of patients with a single episode go on to develop MS over the next 15 years.
3. If MRI shows 3+ white matter lesions, 5 year risk of developing MS is 50%.
4. Contrast sensitivity, colour vision and visual field can remain impaired even after good recovery.