Flashcards in Neuro-ophthalmology Deck (36):
What 3 things should one comment on when describeing an optic disk?
The three C's:
The cup-disk ratio
What are the sings of optic disk swelling
The colour: pink
The contour: Blurred with haemorrhages at the contour
The cup-disk ratio: not enlarged but hard to see anyway
What are some DDx's of optic disk swelling
papilloedema (has to be bilateral)
arteritic anterior ischaemic optic neuropathy (aion)
What is seen on fundoscopy in pt's with optic neuritis?
a swollen disc with a blurred margin
If the inflammation of the optic nerve is further back then the optic disc may not be swollen (retrobulbar neuritis)
with a pink colour and normal cup
What symptoms will a patient with optic neuritis complain of (and what is the typical age demographic)?
1) Blurred vision
2) Dull ache esp. on eye movement
(normally young to middle aged)
What examinations are indicated in optic neuritis and what would the findings be?
Fundoscopy findings (blurred disk margin showing swollen disk or not) and
Visual fields --> reduced centrally due to para-central scotoma or enlarged blind spot.
Swinging flashlight test --> RAPD
What investigations should be done in recurrent optic neuritis?
MRI to check for MS
What does papilloedema mean?
swelling of the optic discs
due to increased intracranial pressure
(therefore must be bilateral)
When is the only occasion that papilloedema can be unilateral?
If the patient has developed optic atrophy in one eye previously
What will a patient with papilloedema complain of?
transient blurring of vision
What are the early signs of papilloedema?
1) haemorrhages at disk margin
2) exudates (lipid break-down products that are left behind after localized edema resolves, they are around the macula)
3) cotton wool spots (debris from dead nerve cells)
4) retinal folds
Bilateral enlarged blind spots (early)
What are the long term signs of papilloedema?
Irreversible atrophic changes of the optic disk
Gradual field loss (late) due to generalised constriction of the optic nerve
What is arteritic anterior ischemic optic neuropathy (AION)?
inflammation of the arteries to the optic disc
which causes infarction
Explain the detailed pathophysiology of arteritic AION.
giant cell (aka temporal) arteritis
where inflammation of the temporal arteries causes occlusion of the
posterior ciliary artery supply to the optic nerve
it hence gets infarcted.
What are the early signs of arteritic AION?
temporal headache and jaw claudication (due to jaw ischemia).
This happens before the optic infarction
Raised CRP and ESR
What is the Ix/Mx for a patient with arteritic anterior ischemic optic neuropathy (AION)?
Urgent high dose steroid (or eye will do within 3 weeks) continued for at 2 YEARS.
Temporal artery biopsy. Within 1 week of starting steroid to give a conclusive diagnosis.
What are the signs of arteritic AION?
disk is pale/white
the margins are blurred
the cup is obliterated and will not be visible
The rest of the fundus will have pallor
What is non-arteritic anterior ischemic optic neuropathy (AION)
A swollen artery, usually due to atherosclerosis. (i.e. due to CV risk factors not from giant cell arteritis)
This causes obliteration of the lumen of the posterior ciliary arteries and the optic nerve gets infracted
What are the features which can be used to differentiate arteritic and non-arteritic AION?
Artertic has a higher level of swelling and
the visual impairment is worse in arteritic
ESR is not raised in non-arteritic as it is not inflammatory
What are the at-risk groups for developing non-arteritic AION?
Hypertensives (50% of pts)
What is the treatment for non-arteritic AION?
What causes optic atrophy and what are the signs on fundoscopy and otherwise?
Anything that causes a disruption/compression of the blood supply to the optic nerve,
will produce optic atrophy
The signs are pale optic disk and RAPD
Describe the pupil light reflex pathway.
Light stimulates the retinal ganglion cells after reaching the light receptors.
This passes down the optic nerve
This goes to the pre tactile nucleus
and then signals are sent to the Edinger-Westphal nucleus on the same and contralateral side.
The signals then pass along parasympathetic neurones along the oculomotor nerve (CN3)
This synapses with the ciliary ganglion cells which
sends short ciliary nerves to the sphincter pupillae causing constriction of the pupil
Describe the pupil near reflex
Information from the light on each retina is taken to the occipital lobe via the optic nerve and optic radiation
where it is interpreted as vision
The peristriate area 19 interprets accommodation
and sends signals bilaterally to the Edinger-Westphal nucleus
it then follows the same pathway as for the light reflex
(vision is not a necessity for this reflex)
What is an afferent pupillary defect?
A total defect in the afferent pathway:
from retinal ganglion cells to the Edinger-Westphal nucleus.
Clinically this means pathology affecting the retina or optic nerve (before the optic chiasm)
What is a relative afferent pupillary defect?
This is similar to APD but is not complete so a minimal slower response will be noticed
as shown with a swinging flashlight test
What causes Horner's syndrome?
a lesion affecting the sympathetic supply to the eyes
What are the signs of Horner's syndrome?
Smaller pupil (paralysis of dilator pupillae)
Ptosis (due to paralysis of sympathetic smooth muscle of the eye lid; superior tarsal muscle, this can also be known as Müller’s muscle but is "less" correct)
What should one check for in general inspection in a pupil examination?
1) Neck scars --> to look for surgery that may have damaged the sympathetic chain
2) Ptosis (could be due to 3rd nerve palsy or Horner's)
Expain the course of the sympathetic pathway to the eye?
1st order neurone: hypothalamus to C7-T1
2nd order neurone (preganglionic):
through the brachial plexus over pulmonary apex and synapses with
superior cervical ganglion (at the angle of manible/bifurcation of carotid artery)
3rd order neurone (postganglionic)
From superior cervical ganglion goes through the adventitia of the carotid artery and enter the cranium to reach the eye.
It innervates the:
Dilator muscles of the iris
Superior tarsal muscle
What is the cause of Argyll Robertson pupils?
Tertiary syphilis (neurosyphilis affecting the midbrain)
What are the signs of Argyll Robertson pupils?
Bilaterally small pupils that dont respond to light
Light-near dissociation (is a negative reaction to light but a positive reaction to accommodation)
What are the symptoms of Argyll Robertson pupils?
Blindness due to optic atrophy
Can present with uveitis
What is Adie's pupil?
in an otherwise health patient
It is thought to be due to a viral/bacterial infection of the ciliary ganglion and autonomic system
What are the signs for Adie's pupil?
poor pupil response to light
a slow response to accommodation