Neurophthalmology Flashcards
Causes of optic disc pressure
Papilloedema
Optic neuritis
Anterior ischaemic optic neuropathy
Severe hypertension
Horner syndrome
- Features
Dysfunction of the sympathetic system:
- Miosis (constricted pupils)
- Ptosis
- Ipisilateral Anhidrosis
CN3 palsy presentation
Globe deviation
- Eyeball down and out
Abnormally dilated pupil
Ptosis (levator
CN6 palsy presentation
Inability to abduct the eye
- can present with binocular horizontal diplopia (diplopia due to ocular misalignment)
Horner syndrome
- Causes
Pancoast tumour
- Lung cancer at the apex
Carotid artery dissection
- Sympathetic pathway to the eye travels along here
Investigations for Horner syndrome
Chest X-ray
- rule out pancoast tumour
Head MR or CT angiogram
- Rule out carotid dissection
Confirmation of Horner’s in subtle cases
- cocaine or apraclonidine drops = dialtion of pupils if normal sympathetic function
Head CT/ MRI if other neurological deficits arise
Describe the optic pathway
- Retina
- Right and left optic nerve
- Innervates respective side bilaterally - Optic chiasm
- Right and left optic nerves from contralateral eye cross to their respective sides. - Optic tract
- Right and left optic nerve fibres on respective sides. Containing contralateral fibres. - Lateral geniculate nucleus (LGN)
- Relay centre in the thalamus for the visual pathway, receiving fibres from the optic tract. - Upper and lower optic radiations
- Axons from the LGN that go directly to the primary visual cortex
- Upper radiations= upper quadrant vision
- Lower radiations= lower quadrant vision - Primary visual cortex: calcarine fissure
- Upper bank= receives fibres from lower optic radiations
- Lower bank= receives fibres from upper optic radiations
autoimmune causes of optic neuritis
- SLE
- Neuromyelitis optica (myelitis and optic neuritis)
- Sarcoidosis
- Bechet’s disease (vasculitis)
- Granulomatosis with polyangitis
Investigations for optic neuritis
Brain MRI
- Investigate for MS
- Characteristics of other causes
Lumbar puncture
- Oligoclonal bands and elevated IgG supports MS diagnosis
Atypical features (i.e. bilateral, chronic, not resolving)
- Bloods: FBC, ESR, TFTs, autoantibodies
- Serology testing for neuromyelitis optic immunogolobulin
- CXR (sarcoidosis, TB, malignancy)
Types of optic neuritis
Dependent on the region of the nerve affected:
Retrobulbar
- posterior nerve affected
Intrabulbar/ papillitis
- head of nerve affected
Neuroretinitis
- involvement of optic disc and surrounding retina
Treatment of acute, idiopathic optic neuritis
Oral/ IV methylprednisolone
Deficiency of what vitamin can cause optic neuritis?
Vitamin B12
Toxicity from which cardiac drug can cause optic neuritis?
Amiodarone
Presentation of optic neuritis
Symptoms:
- Unilateral retrobulbar/ ocular pain on eye movement
- Subacute visual loss.
- Loss of colour vision (Dyschromatopsia)
Signs
- Reduced visual acuity
- Weaker direct pupillary response
- Optic disc swelling
- Scotoma
Management of demyleinating/ idiopathic optic neuritis
IV/ Oral methylprednisolone
