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Opthalmology > Pupillary Reflexes > Flashcards

Pupillary Reflexes Flashcards

1
Q

What is the pathway for pupil constriction

A

light hits retina - retinal ganglion cell fires down retinal ganglion axons to the lateral geniculate nucleus (in thalamus) and the pre-tectal area - pretectal area fires to both acessory oculomotor nuclei (1 on either side), these then send axons to preciliary ganglion fibres, that synapse in the ciliary ganglion, sending post ganglionic fibres to the ciliary muscle which synapse and cause contriction

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2
Q

what is the edinger-westphal nucleus

A

accessory oculomotor nucleus - the parasympathetic nucleus of CN3

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3
Q

What cranial nerves are tested by pupillary reflexes

A

CN2 + 3

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4
Q

What is the sympathetic pathway for pupil dilation

A

hypothalamic fibres travel to T1 and enter the sympathetic chain, they then ascend to the superior cervical ganglion and synapse with post-ganglionic sympathetic fibres

post-ganglionic fibers situated along internal carotid and travel with opthalmic artery

in the orbit, fibres pass through the ciliary ganglion synapsing with the long ciliary nerve to reach eyeball

in eyeball fibres innervate dilator pupillae muscle

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5
Q

what does the tectospinal tract regulate

A

reflexive motor adjustement in response to visual stimuli

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6
Q

What is RAPD

A

pupil dilation when a bright light is swung from the unaffected eye to the affected eye (in reality it is just constricting less but it looks like its dilating)

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7
Q

what causes RAPD

A 
optic nerve ischaemia 
optic neuritis 
compression 
asymmetric glaucoma
central retinal arter/vein ischemia/occlusion 
large retinal detachment
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8
Q

what is horners syndrome

A

sympathetic dysfunction due to upper thoracic compression of the sympathetic chain

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9
Q

what is a common cause of horners syndrome

A

pancoast tumour

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10
Q

what are PRIMARY causes of horners syndrome

A

CNS disease
cervical comression
diabetic neuropathy

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11
Q

what are secondary causes of horners syndrome

A 
cervical rib
pancoast tumour
aortic/carotid aneurysm
opical TB
neck trauma
lymphadenopathy
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12
Q

what is the classic triad of symptoms of horners syndrome

A

unilateral ptosis (eyelid drop), miosis (pupil constriction) and anhydrosis (dry skin)

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13
Q

how do you diagnose horners syndrome

A

non-dilation using cocaine 4% or dilation on apraclonidine 0.5%

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14
Q

what are the symptoms of 3rd nerve palsy

A

ptosis
dilated pupil
eyes looking down and out

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15
Q

what are the causes of 3rd nerve palsy

A 
brainstem tumour
CVA
demyelination
skull base haematoma
cavernous sinus tumour/fistula/inflammation
orbit tumour/trauma/inflammation 
vascular palsy 
surgical lesion 
uncal herniation
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16
Q

what is a feature of a vascular 3rd nerve palsy

A

pupils are spared

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17
Q

what is adies pupil

A

pupil dilation
absent light response
slow near response (no light reflex, slow but present near response)
slow tendon reflexes

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18
Q

what causes adies pupil

A

ciliary ganglion problems

19
Q

what is the usual demographic for adies pupil

A

young females

20
Q

how do you diagnose adies pupil

A

pilocarpine will constrict the affected pupil

21
Q

what is argyll robinson pupil

A

neurosyphillis causing small irregular pupils and light-near dissociation (can accommodate better than light response)

22
Q

what is traumatic mydriasis

A

dilated pupils in response to blunt trauma damaging the sphincter iris muscle

23
Q

what is posterior synechiae

A

following intraocular inflammation, the iris pigment epithelium adheres to the lens resulting in an irregularly shaped pupil

24
Q

what do you see in the accomodation reflex

A

convergence and contriction

25
Q

what does anisocoria mean

A

asymmetric pupils

26
Q

What is defined as asymmetric pupils

A

when they’re different by >1mm

27
Q

what is the common inital presentation of CN3 palsy

A

diplopia when focusing horizontally to the left/right

28
Q

what are some common causes of diplopia

A

myasthenia gravis
graves
Cranial nerve palsy

29
Q

what is a common symptom of myasthenia gravis

A

symptoms occur at the end of the day

30
Q

what extracranial nerves exist in the cavernous sinus

A

lacrimal nerve
CN3
maxillary and opthalmic division of the trigeminal
CN4

31
Q

where are the nuclei of CN3

A

medial midbrain

32
Q

how can you tell a nuclear Cn3 palsy and an infranuclear CN3 palsy

A

other eye normal = infranuclear

33
Q

what is adies pupil + decreased tendon reflexes called

A

homes-adies syndrome

34
Q

how do you fix mydriasis

A

contact lens that mimics iris position of normal light in the other eye to minimise ‘glare phenomenon ‘

35
Q

what are some causes of the inflammation preceding posterior synechiae

A 
corneal ulcer (most common) 
uveitis/anterior iritis
endophalmitis
36
Q

how do you treat posterior synechiae

A

dilate pupil and check for choroidal inflammation

give steroids + dilating agents to prevent sticking

37
Q

why are dilating agents helpful in posterior synechiae

A

prevent ciliary muscle spasm which causes most of the pain, as well as allowing aqeuous build up behind the iris to drain causing secondary glaucoma

38
Q

why does RAPD occur

A

slowed rate of conduction

39
Q

what should the top differential be for an abnormally enlarged pupil

A

adies pupil

40
Q

what is the most likely diagnosis of an abnormally enlarged pupil with near-light dissociation , and what is the next management step

A

adies, check tendon reflexes

41
Q

whats the top differential of an abnormally enlarged pupil with no near-light dissociation

A

CN3 palsy

42
Q

whats the top differential of an abnormally enlarged pupil with no near-light dissociation and normal eye movements

A

traumatic myadriasis

43
Q

whats the top differential of an abnormally enlarged pupil with no near-light dissociation and abnormal movements

A

CN3 palsy

Opthalmology (16 decks)

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