pupil disorders Flashcards
what can cause abnormal pupil shape?
TRAUMA to sphincter muscles
anterior uveitis
AACG
rubeosis iridis
colobama
tadpole pupil
how can trauma to sphincter muscle cause abnormal shape?
sphincter muscle is within iris
can be from cataract surgery
what is anterior uveitis?
adhesions - scar tissue within iris
causing irregular pupil shape
how can AACG cause irregular shape?
ischaemic damage to muscles of iris and abnormal pupil shape
what is rubeosis iridis?
neovascularisation of iris and can distort shape of iris/ pupil
what is colobama?
congenital malformation that can cause a hole in iris and irregular pupil shape
what is tadpole pupil?
muscle spasm in part of dilator or iris - misshapen pupil
what is tadpole pupil associated with?
migraines and horners
what is mydriasis?
dilated pupil
what can cause mydriasis?
congenital
stimulants - cocaine
anticholinergics - oxybutinin
trauma
third nerve palsy
holmes - adie syndrome
raised ICP
AACG
what is holmes-adie syndrome?
rare neuro condition
pupil remains relatively dilated and does not react to light
what is miosis?
pupil constriction
what can cause miosis?
horner syndrome
opiates
nicotine
pilocarpine
cluster headaches
argyll-roberston pupil
what is argyll roberston pupil?
neurosyphilis
remain small and do not react to light
what features are seen in third nerve palsy?
ptosis
dilated non-reactive pupil
divergent strabimus
what is ptosis?
drooping of eyelid
what is divergent strabismus?
squint in affected eye
gives down and out appearance
which cranial nerve is the 3rd?
occolumotor
what does the CNIII supply?
all extraoccular except lateral rectus and superior oblique
how do you assess CNIII?
do 2,3,4,6 together
light reflex
H test
looking distance and back to finger
why does third nerve palsy cause eyelid drooping (ptosis)?
CNIII also supplies levator palpedbrae superiosis
this is resposible for lifting eyelid
what nervous system does CNIII supply?
parasympathetic - rest and digest
why does third nerve palsy cause dilated and non-reactive pupil?
CNIII supplies parasympathetic to circular muscles of iris
what can cause typical third nerve palsy?
idiopathic
what could cause third nerve palsy without affecting pupil be caused by?
microvascular cause
parasympathetic fibres are spared
- diabetes
HTN
- ischaemia
what causes a full third nerve palsy?
compression of nerve
including compression of parasympathetic fibres
- trauma
- tumour
- cavernous sinus thrombosis
- posterior communicating artery aneurysm
- raised ICP
what is cavernous sinus thrombosis?
blood clot within this sinus
sinus located behind eye socket
why can posterior communicating artery aneurysm cause full third nerve palsy?
CNIII travels directly from brainstem in a straght line very close to PCA - a aneurysm would push it
why can a cavernous sinus thrombosis cause full third nerve palsy?
CNIII travles directly from brainstem to eye in a straght line
- blood clot would push against it as the nerve travels through the sinus
what is the horner syndrome triad?
ptosis - drooping eyelid
miosis - pupil constriction
anhidrosis - loss of sweating
what sign may also be seen within horners?
enophthalomas
sunken eye
light and accomodation reflexes not affected
what causes horner syndrome?
damage to sympathetic chain
what type of ganglion nerve are the ones affected within horners?
pre-ganglion - enter from spinal cord at base of neck
how can the location of lesion be determined by horner symptoms?
anhidrosis location:
arm, trunk and face - central lesions
face - pre ganglionic
no anhidrosis - post ganglion
what are the underlying pathologies for horners? - pre ganglion
4S, 4T
4S: central lesions - Stroke, mS, Swelling (tumours), Syringomyelia (cyst in spinal cord)
T: pre ganglionic - Tumour (pancoast), Trauma, Thyroidectomy, Top rib (cervical rib growing above first rib)
what is the underlying pathology for post ganglion horners?
4Cs
carotid aneurysm
carotid artery dissection
cavernous sinus thrombosis
cluster headache
what is congenital horner syndrome associated with?
heterochromia - difference in colour on affected side
how can you test for horner syndrome?
cocaine eye drops
low dose adrenaline eye drops will dilate pupil in Horner syndrome
what is Holmes-addie syndrome?
holmes addie pupil associated with absent ankle and knee reflexes
damage to post-ganglion fibres
