AVL: Optic nerve disorders

Question 1

What is optic neuritis?

Answer 1

Inflammation of the optic nerve

Question 2

Causes of optic neuritis

Answer 2

Infections
- Post infectious/ vaccinations
- Bacterial (TB/ Syphilis)
- Viral (Hep/ Herpes Zoster)
- Fungal (Cryptococcus)
- Adjacent meningitis/ sinusitis

Inflammatory
- Autoimmune: SLE, Vasculitis
- Sarcoidosis

Demyelinating
- Multiple sclerosis***
- Neuromyelitis Optica (Inflammation and demyelination of the optic nerve (optic neuritis) and the spinal cord (myelitis))

Idiopathic

Question 3

Clinical presentation of optic neuritis

Answer 3

• Unilateral/bilateral depending on cause
• BoV/Vision loss over a period of hours/ days peaking 1-2 weeks
• Eye pain worsened with eye movement*
• Visual field central scotoma*
• Photopsia (Flashes of light)
• Loss of color vision
• Recent viral illness/ immunization

Question 4

Signs in optic neuritis

Answer 4

• RAPD
• Color desaturation (Ishihara)
• Visual field defect (Central scotoma)
• Fundoscopy: Optic disc swelling

Question 5

How is optic neuritis classified?

Answer 5

Based on appearance of optic disc

Papillitis:
Optic Disc swelling
- Hyperemia of disc
- Blurring of disc margins
- Distended veins

Retrobulbar Neuritis
- NIL optic disc swelling

Neuroretinitis
- Optic disc swelling and peripapillary retina

Question 6

Investigations for optic neuritis

Answer 6

Perform fundoscopy of other eye
MRI Brain and orbits
- demyelinating plaques in cerebral/ intraocular inflammation
Lumbar puncture
Visual evoked potentials
Fluorescein angiography
Optical coherence tomography

Question 7

Management of optic neuritis

Answer 7

Vision usually improves over 2-3 weeks if cause is idiopathic or related to demyelination

Tx:
IV methylprednisolone followed by oral prednisolone to expedite visual recovery

Question 8

What is the risk of developing multiple sclerosis in optic neuritis?

Answer 8

Depends on the presence of brain lesions in demyelinating optic neuritis
+ve: 72%
-ve: 15%

Question 9

What is ischemic optic neuropathy?

Answer 9

Ischemia to optic nerve head

Question 10

Types of ION

Answer 10

Anterior portion of optic disc affected
- Swollen disc
*further classified between arteritic and non-arteritic ION

Posterior portion of optic disc affected
- Normal optic disc

Question 11

Arteritic ION

Answer 11

• Giant cell arteritis
• Polymyalgia rheumatica
• Collagen vascular disease
• ESR, CRP elevated (supportive finding)
• Elderly, >70y/o

Question 12

Non-arteritic ION

Answer 12

• Most common
• Idiopathic ischemic insult on optic nerve head
• Poor perfusion in circulation of posterior ciliary artery supplying optic nerve
• Atherosclerotic RF: HTN, DM, Vascular RF, >50y/o, inflammatory conditions (SLE R.A.)

Question 13

Risk factors of non-arteritic ION

Answer 13

Ocular
- small, crowded disc

Systemic
- hypertension
- diabetes mellitus
- hyperlipidaemia
- ischaemic heart disease
- carotid artery disease
- sleep apnoea
- smoking

Question 14

Clinical presentation of non-arteritic ION

Answer 14

• Acute, monocular, painless visual loss typically on waking up in the morning*
• Variable visual acuity (Normal/ Decreased)
• Colour desaturation
• Visual field defect but inferior altitudinal defect is common
• RAPD
• Optic disc is usually swollen with either hyperaemia/ pallor

Question 15

Clinical presentations of arteritic ION

Answer 15

Similar to non-arteritic ION
- Acute, Bilateral, rapidly sequential severe visual loss
- GCA symptoms: headache, malaise, jaw claudication, scalp tenderness, proximal myalgia, arthralgia
- Pale, swollen disc

Question 16

Investigations to send for arteritic ION

Answer 16

For GCA:
ESR**/CRP (Autoimmune/GCA)
Temporal Artery Biopsy (GCA)

Question 17

Investigations to send for non-arteritic ION

Answer 17

BP, fasting lipids, fasting glucose, HbA1c, sleep study

Question 18

Management for arteritic ION

Answer 18

Tx with corticosteroids ASAP to prevent other eye involvement

Question 19

Management of non-arteritic ION

Answer 19

Treat cardiovascular RFs