Pupils

mid-dilation

when is the greatest risk of pupil block?

optic nerve

a lesion at what site is the most common cause of a severe RAPD?

no

can you get a RAPD from a purely chiasmal lesion?

yes

can you get an RAPD from an optic tract lesion?

30:1 ratio of near:light fibers

what allows for light-near dissociation? 

miosis, accommodation, convergence

what are the parts of the near reflex?

levator inhibition, superior rectus muscle activation, miosis

what are the parts of Bell’s phenomenon?

orbicularis oculi, unilateral or bilateral miosis

what are the parts of the Westphal-Piltz reaction?

near reflex, Bell’s phenomenon, Westphal-Piltz rxn

what are the synkinetic rxns of the parasympathetic system? 

NE, alpha

what neurotransmitter is released at the dilator muscle & what receptor does it stimulate?

hippus

• pupillary unrest

• rhythmic

• 1-2mm

• bilateral

• independent of stimulation

• unknown significance

31

the pupils of premature neonates are non-reactive to light until ____wks gestation 

benign anisocoria (aka essential or physiological)

• 20% of population

• <1mm difference

• inequality is the same under all lighting conditions

• may occasionally switch sides or be transient

benign episodic unilateral mydriasis (springing pupil)

• F>M

• age: 2nd-3rd decade

• associations: migraine w/ mild blur, photophobia, HA, orbital pain

1. parasympathetic insufficiency of iris sphincter

2. sympathetic hyperactivity of iris dilator 

what is the benign neurologic prognosis of springing pupil? 

efferent

anisocoria is a _________ (afferent/efferent) disorder

fixed pupil

no rxn to light or accommodation

1. pharmacologic blockade

2. trauma or inflammatory (traumatic mydriasis, iris damage/atrophy, sphincter tears, posterior synechiae, acute angle closure glaucoma) 

3. structural abnormalities (mechanical or surgical) 

what are the possible etiologies of a fixed pupil?

naphcon 

what is an example of a topical drug that can cause a fixed pupil? 

heroin, morphine, codeine

what are some systemic drugs that can cause a miotic fixed pupil?

dramamine, cocaine, levodopa, antihistamines, Belladonna, jimsonweed plants

what are the some systemic drugs that can cause a mydriatic fixed pupil?

1% pilo will constrict a compressive CN3 or Adies’s tonic pupil but not all pharmacologically-induced pupils

how do you dx a fixed pupil?

pilocarpine, metacholine, physostigmine 

what are the parasympathetic agonists? 

atropine, tropicamide, cyclogyl, botulinum A toxin

what are the parasympathetic antagonists?

thymoxamine, dapiprazole

what are the sympathetic antagonists?

phenylephrine, hydroxyamphetamine

what are the sympathetic agonists?

RAPD

• unilateral or asymmetrical impaired function of the retina or optic nerve, possibly optic tract

• less stimulation is received by the EW nucleus when light is directed into the affected eye 

contralateral

if there is an optic tract lesion causing an RAPD, the RAPD will be _____ to the lesion

1. optic neuropathy: optic neuritis, ION, traumatic, compressive, asymmetric glaucoma

2. retinal conditions: RD or macular disease, CRAO

3. optic tract lesion

what are the possible etiologies of an APD?

1. RE

2. malingering

3. corneal opacities

4. cataracts

5. vitreous opacities

6. subtle retinal lesions

7. visual pathway lesions posterior to the LGN 

what ocular conditions will NOT cause RAPD? 

normal

when quantifying an RAPD w/ an NDF, what eye do you put the NDF over? 

put the filter over the normal eye and perform the swinging flashlight test, increasing the filter until the defect disappears

how do you quantify an RAPD?

observe the consensual response in the fellow eye 

when the pupil doesn’t react, how do you assess optic nerve function? 

light-near dissociation

• unequal rxn to light & accommodation

• occurs when afferent fibers are disrupted in pretectal region

• unequal mid-dilated or miotic pupils

1. encephalitis/meningitis

2. demyelination

3. pretectal lesions

4. diabetes

5. aberrant regeneration of CN3

6. bilateral afferent disease

what are some potential etiologies of light-near dissociation?

Argyll-Robertson pupil 

• bilateral, asymmetrical miosis 

• lesion: midbrain light reflex pathway 

• s/sx:

  • frequently irregular pupils

  • respond poorly to dilating agents 

  • virtually no response to light

  • brisk response to near

  • normal VA

1. neuro-syphilis

2. neuro-sarcoidosis

3. multiple sclerosis

4. diabetes (rare)

what are some possible etiologies of Argyll-Robertson pupil?

dorsal midbrain syndrome (Parinaud’s syndrome)

• lesion: dorsal midbrain (tectal, posterior commissure, superior colliculus) 

• s/sx: 

  • light-near dissociation

  • convergence-retraction nystagmus

  • vertical gaze palsy (limited upgaze)

1. hydrocephalus

2. pineal tumor

3. trauma

4. vascular malformation

5. ischemia

what are some possible etiologies of dorsal midbrain syndrome?

Adie’s Tonic pupil 

• F>M

• age: 2nd-4th decade

• unilateral → bilateral

• lesion: benign lesion of ciliary ganglion 

  • leads to neuronal loss & aberrant regeneration

• s/sx: 

  • acute - dilated, fixed pupil

  • old - becomes more miotic

  • mild light-near dissociation

    • poor/absent response to light

    • slow/tonic response to accommodation w/ slow re-dilation

  • areas of sectoral paresis of iris sphincter & ciliary body (vermicular/worm-like contraction of iris border)

  • diminished/absent deep tendon reflexes

1. idiopathic

2. Herpes Zoster

3. diabetes

4. Guillain-Barre syndrome

5. orbital trauma & infection

what are some etiologies of Adie’s Tonic pupil?

0.125%

what dose of pilocarpine is used to help ddx Adie’s Tonic pupil?

Adie’s pupil constricts

normal pupil will not constrict 

describe the pupil responses when using 0.125% pilocarpine to DDx Adie’s Tonic pupil 

hypersensitive

Adie’s Tonic pupil is ___________ to week cholinergics

both pupils constrict

describe the pupil responses when using 1% pilocarpine to DDx Adie’s Tonic pupil

Horner’s syndrome

• lesion: sympathetic pathway

• s/sx:

  • miosis (anisocoria w/ affected pupil is smaller) 

    • most noticeable in dim illumination 

    • normal light & near rxns 

  • unilateral ptosis & upside down ptosis 

    • paralysis of Muller’s muscle & loss of muscle tone 

  • facial anhidrosis (if prior to the SCG) 

  • conjunctival hyperemia 

  • heterochromia (if congenital))

  • hypotony

sympathetic 

4 or 10% cocaine requires a functional __________ pathway 

normal pupil dilates

Horner’s pupil does not dilate 

describe the pupil responses when using 4% or 10% cocaine to DDx Horner’s syndrome 

Horner’s pupil dilates

normal pupil will not 

describe the pupil responses when using 0.5% or 1% apraclonodine to DDx Horner’s syndrome 

no

does 4% or 10% cocaine differentiate the Horner’s lesion site?

no 

does 0.5% or 1% apraclonodine differentiate the Horner’s lesion site? 

yes

does 1% hydroxyamphetamine differentiate the Horner’s lesion site?

if preganglionic, dilation 

if postganglionic, no dilation 

normal pupil dilates

describe the pupil responses when using 1% hydroxyamphetamine to localize the sympathetic lesion in Horner’s syndrome? 

if preganglionic, minimal to no dilation

if postganglionic, dilation

normal pupil has minimal to no dilation

describe the pupil responses when using 1% phenylephrine to localize the sympathetic lesion in Horner’s syndrome? 

neoplasm, trauma, vertebrobasilar insufficiency

what can cause a 1st order Horner’s syndrome?

pancoast or thyroid tumor, neck trauma or surgery

what can cause a 2nd order Horner’s syndrome?

cavernous lesion, dissecting carotid aneurysm, cluster HA, neoplasm, trauma, peripheral neuropathy, inflammation/infection 

what can cause a 3rd order Horner’s syndrome? 

pre

there is a higher risk of malignancy if the Horner’s syndrome is due to a ___ganglionic lesion

internal carotid artery dissection

what is the concern if a pt presents w/ Horner’s syndrome & pain?

partial vs complete CN3 palsy

• fixed dilated pupil

• paralysis of accommodation

• ptosis

• restricted motility: down & out

• preservation of CN4&6

aneurysm 

if there is a pupil involving CN3 palsy, what is the presumed cause? 

ischemic

if there is a pupil sparing CN3 palsy, what is the usual cause?

mydriasis & decreased accommodation

if there is an interruption in parasympathetic innervation, what are the results?

miosis

if there is an overaction in parasympathetic innervation, what are the results?

miosis 

if there is an interruption in sympathetic innervation, what are the results?

mydriasis

if there is an overaction in sympathetic innervation, what are the results?

afferent

anisocoria is an ______(afferent/efferent) disorder

1. CN3 palsy

2. acute Adie’s Tonic pupil

3. pharmacologic-induced mydriasis

4. iris damage

5. sympathetic irritation

what are the DDx for an abnormally large pupil?

1. Horner’s syndrome

2. simple anisocoria

3. old Adie’s tonic pupil 

4. pharmacologic induced miosis

5. parasympathetic irritation 

what are the DDx for an abnormally small pupil?

sympathetic 

if the anisocoria is greater in dim illumination, it is a ______ pathway issue 

parasympathetic

if the anisocoria is greater in bright illumination, it is a ______ pathway issue