Optic Neuritis

Question 1

Define optic neuritis

Answer 1

Inflammation of the optic nerve

Question 2

Aetiology of optic neuritis

Answer 2

Idiopathic ON: multiple sclerosis
Neuromyelitis optica spectrum:
- Features of autoimmune disease
- Chronic relapsing inflammatory optic neuropathy
- Post-infection/post-vaccine conditions e.g. disseminated encephalomyelitis
Neuropathies associated with autoimmune disease e.g. SLE, Sarcoidosis, Sjogren’s, Behcet’s
Infection: Lyme disease, syphilis

Pathological features of MS/ON: inflammation, demyelination, axonal loss, and gliosis

Question 3

Symptoms and signs of optic neuritis

Answer 3

Peri-orbital/retro-orbital pain
- Especially on movement
Loss of visual acuity
- Visual acuity loss ranges from minimal to severe and reaches nadir in 1 to 2 weeks. Described as seeing through cloud, through fog, through a window with rain drops trickling down.
Field defect: scotoma
Loss of colour vision
Relative afferent papillary defect
Papilloedema
MS signs

Question 4

Investigations for optic neuritis

Answer 4

FBC
ESR/CRP: ?GCA
VDRL: ?syphilis
Neuromyelitis optica antibody (NMO) and anti-myelin oligodendrocyte glycoprotein (MOG): ?NMOSD?MOG
Uric acid: low
Serum ACE: ?Sarcoidosis
ANA: ?SLE

MRI optic nerves: swelling of optic nerve; enhancement in optic nerve
- MS → white matter lesions

Question 5

Management for optic neuritis

Answer 5

IV pulse methylprednisolone 1000mg for 3 days → PO prednisolone

Question 6

Prognosis for optic neuritis

Answer 6

Recovers spontaneously, typically over weeks/months
General visual prognosis is good
8% have residually decreased acuity <20/40