Pupillary Pathway Flashcards
near pupil response pathway efferent
cn3 sphincter (miosis) + cb (acc) -Mr convergence
consensual pupillary light response
constriction of contralateral eye
dorsal midbrain- pineal gland
- paralysis of upgaze bilateral
- convergent refraction syndrome- eyes converge with trying to look up
- eyelid retraction
Disruption of the efferent sympathetic pathway: Horner syndrome
pathway - preganglionic
spinal cord –> apex of lungs –> superior cervical ganglion
disruption in the central nervous system pathway causes
lesion of the midbrain can affect the tract between the pretectal and EW nucleus
dorsal midbrain syndrome
- bilateral light - near dissociation
- pupils are normal to mid-dilated
- most commonly due to pineal gland abnormality
in efferent sympathetic pathway is anisocoria better or worse in dim illumination
worse
efferent parasympathetic pathway causes- cn3 palsy
- also innervates sr, mr, io, ir, levator sphincter, cb
- ischemic lesion –> pupils spared
- aneurysm –> pupils involved
causes of RAPD retina
large lesion needed bc fibers are spread out
physiological anisocoria
- 20% of pop, can switch eyes
- more apparent in dim illumination - sympathetic, but no other problem
- <1 mm difference
- reactive to light + acc
- no dilation lag (usually seen w/ horner’s)
RAPD brachium
RAPD with normal vision (only place this happens)
efferent parasympathetic pathway cause- pharmacologically dilated pupil
- fixed dilation, worse in bright
- pharm testing 1% pilocarpine
- 0.13% pilo –> constriction = tonic
- 1% pilo –> remains dilated –> pharm dilated pupil
what is light-near dissociation
near pupil response bypasses the central portion of the pupillary light response
-acc, convergence, miosis
argyll roberston pupil
-bilateral light near dissociation (-) light (+) acc -without light stimulus the pupils will be very small <1mm -most commonly due to neurosyphilis also due to Dm, chronic alcoholism , ms -lesion likely in central light pathway
Pharmacologic testing
- Diagnostic: 5-10% ophthalmic cocaine
a. Indirect acting adrenergic agonist
normal = dilation horner's= no dilation
efferent lesion light near
affects near + light response due to overlap of pathway
cataracts and RAPD
cataracts do not cause an ipsilateral RAPD
- cataract –> spreading light –> more fibers simulated –> other eye may look like it has APD
- if cataract and APD then its not cause- look for something else
efferent parasympathetic pathway cause- tonic pupil
-caused by damage to the ciliary ganglion or short ciliary nerves
-segmental constriction- only segment of iris constriction (purse-string effect- not uniform constrction -slow)
-decreased corneal sensitivity
-slow and prolonged near pupillary response (light near dissociation)
-cholinergic denervation supersensitivity
(when some nerves are damaged the remaining nerves are supersensitive; dilted 0.13% pilocarpine will constrict these nerves)
pancoast tumor
tumor at apex of lungs
- injury to thoracic area (heart surgery)
efferent parasympathetic pathway cause- damage to iris
trauma- post surgery
inflammation- syneichiae
ischemia- due to angle closure, will have high pressure
RAPD grading
grade 3
immediate dilation
horner’s + cn6 palsy
look @ cav sin likely aneurysm of ICA within sinus, cannot abduct, ptosis, miosis
causes of RAPD optic nerve
very small lesion –> very large APD b/c fibers are compressed
- Alternative diagnostic agents
b. 1% phenylephrine
normal= minimal dilation horner's= a lot of dilation due to super sensitive post ganglion
efferent
leaving CNS (motor) going to eyeball
efferent parasympathetic pathway cause- tonic pupil causes
- autonomic- bilateral, diabetes
- orbital mass- unilateral
- orbital trauma/surgery - unilateral
- idiopathic (adie tonic pupil)
direct pupillary light response
constriction of ipsilateral eye
RAPD optic tract
get APD contralateral to the lesion with complete homonymous hemianopia more nasal
-more nasal fibers cross at chiasm –> see on opposite side
RAPD grading
grade 1
grade 1- weak constriction followed by greater redilation
afferent
brings info to CNS, ON, retin
in efferent parasympathetic pathway is anisocoria better or worse in dim illumination
better
afferent pathway
- afferent pathway follows the visual fibers
- the fibers leave the optic tract and travel within the brachium of the superior colliculus to the pretectal area of the midbrain
- pretectal nucleus (synapse)
- fibers travel to the EW nuclei in posterior commissure (central pathway)
what will the disruption of the afferent pathway affect
disruption of the afferent pathway will affect the direct response of the ipsilateral eye and the consensual response in the contralateral eye
- RAPD
- will not cause anisocoria
RAPD grading
grade 4
no reaction to direct light
RAPD chiasm
unusual bc fibers are crossing
disruption of the efferent sympathetic pathway: Horner’s syndrome
- miosis
- anisocoria greater in dim light
- normal reaction to light (direct and consensual is good)
- dilation lag - not as quickly
(more aniso after 15 secs than 5 secs) - ptosis and pseudoenopthalmos (eye appears sunken in due to ptosis + reverse ptosis of lower lid)
- facial anhidrosis (absence of sweating–> w/ preganglionic or central problem)
- iris heterochromia in congenital horner’s syndrome (melanin is sympathetic system to develop- eye w/ horner’s would be lighter than other eye)
RAPD grading
grade 2
grade 2- no constriction followed by redilation
near pupil response pathway CNS
frontal eye fields–> CNS -nucleus EW + MR
disruption in the efferent parasympathetic pathway
a lesion of the efferent pathway will cause the ipsilateral eye to show poor direct, consensual, and near pupillary responses
(remains ipsi after leaving midbrain)
ipsilateral mydriasis
anisocoria worse in bright light (bad pupil won’t constrict)
Disruption of the efferent sympathetic pathway: Horner syndrome
pathway - postganglionic
follows ICA plexus –> cav sin –> CN5 (nasociliary nerve) –> long ciliary nerves –> dilator
when does light near dissociation occur
disruption in the central NS pathway
adie tonic pupil
mild tonic pupil –> asymptomatic
common- 20-40 yo females
decrease tendon reflexes (via spinal cord)
swinging flashlight test
- dr moves light from one eye to other many times
- make sure each pupil is equally illuminated
- if no damage, there will be little no change in pupil size
- if damage, the ipsilateral pupil will dilate when shining light alternately between the eyes
near pupil response pathway
-afferent
(visual pathway to the striate cortex)
- Alternative diagnostic agents
a. Apraclonidine 0.5 or 1%
(1) Alpha adrenergic agonist
- normally lowers pressures
- works on tm, bm, usually no dilation
- normal= no dilation
- horner’s= dilation (w/ pre or post)
efferent pathway parasympathetic
ew nucleus –> through cn3 –> inferior division of cn3 –> synapse in ciliary ganglion –> follows short ciliary nerves –> iris sphincter
- Localization: 1% hydroxyamphetamine
a. Indirect acting adrenergic agonist
pre= dilation post= no dilation
Disruption of the efferent sympathetic pathway: Horner syndrome
pathway - central
hypothalamus –> brainstem –> cervical spinal cord (T1-T2) –>
