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245 > 8.1 Pupils > Flashcards

8.1 Pupils Flashcards

1
Q

What is an efferent pupil defect? Any key features?

A

Motor defect; lesion to system carrying signal from CNS to iris

Key feature: anisocoria

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2
Q

What is an afferent pupil defect? Key features?

A

Lesions in the initial signalling pathway (usually retina or optic nerve)

Key features: abnormal signalling reflexes, no anisocoria

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3
Q

Mydriasis mechanism? (including neurotransmitters and receptors)

A

Mydriasis = dilation

Excite sympathetic system, inhibit parasympathetic

Norepinephrine acts on α-adrenergic receptors and stromal elastic expansion

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4
Q

Miosis mechanism? (including neurotransmitters, receptors)

A

Miosis = constriction

Excite parasympathetic, inhibit sympathetic

Acetylcholine acts on muscarinic receptors

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5
Q

Equal pupil sizes in light and dark indicates ….

A

Normal light reflex, normal pupils

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6
Q

Unequal pupil size

In light: OD is 5mm, OS is 6mm

In dark: OD is 7mm, OS is 8mm

A

Normal light reflex, physiological anisocoria

Disparity is the same in light and dark conditions and is less than 2mm (could still be physiological anisocoria if >2mm but very uncommon)

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7
Q

Light on right eye: OD 5mm, OS 5mm

Light on left eye: OD: 3mm, OS 3mm

No light perception in right eye

A

Absolute afferent pupil defect (OD affected in this case)

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8
Q

Swinging flashlight test

Light on right eye: OD: 3mm, OS 3mm

Light on left eye: OD: 4mm, OS 4mm

A

Relative afferent pupil defect (OS affected in this case)

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9
Q

Abnormal light reflex, no light perception

A

absolute APD

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10
Q

Abnormal light reflex, light perception is fine

A

Relative APD

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11
Q

Abnormal light reflex, bilateral, near reflex normal

A

Argyll Robertson pupil (efferent defect)

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12
Q

Abnormal light reflex, bilateral, near reflex abnormal

A

Drug induced pupil issue likely, efferent

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13
Q

Abnormal light reflex, anisocoria, no ptosis, near defect

A

Adie’s tonic pupil (efferent)

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14
Q

Abnormal light reflex, anisocoria, no ptosis, intermittent near defect

A

Tourney phenomenon (efferent)

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15
Q

abnormal light reflex, anisocoria, no ptosis, no near defect, no trauma or drugs

A

Hutchinson’s pupil (efferent)

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16
Q

abnormal light reflex, anisocoria, no ptosis, no near defect, trauma

A

Iris sphincter damage (efferent)

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17
Q

abnormal light reflex, anisocoria, no ptosis, no near defect, drugs

A

Pharmacological pupil (efferent)

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18
Q

abnormal light reflex, anisocoria, ptosis, + (XOT - down and out eye position)

A

3rd nerve palsy (efferent defect)

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19
Q

abnormal light reflex, anisocoria, ptosis, anhydrosis

A

horner syndrome (efferent defect)

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20
Q

Pupils are equal in size in _____ pupillary defects

A

afferent

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21
Q

Ocular associations of afferent pupil defects

A

reduced VA, colour vision defects, central visual field defects, abnormal VEP (visual evoked potential)

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22
Q

Minor causes of afferent pupil defect ?

A

Very mild: amblyopia, vitreous hemorrhage

Mild: macular degeneration, BRVO/BRAO, retinal detachment, other retinal disease

(BRVO/BRAO = branch retinal vein/artery occlusion)

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23
Q

Major causes of afferent pupil defects

A

(think nerves and blood)

  1. Optic nerve disease: ischemic optic neuropathy (ION), optic neuritis, optic atrophy, tumour, glaucoma)
  2. Ischemic CRVO/CRAO (central retinal vein/artery occlusion)
  3. RAPD: optic chiasm and tract lesions (infarcts, demyelination)
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24
Q

Absolute afferent pupil defect (type of lesion, alternative name)

A

Complete optic nerve lesion

aka amaurotic pupil

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25
Q

Absolute afferent pupil defect (signs)

A

Pupils equal in size

Involved eye is blind (no light perception)

Normal eye stimulated with light = normal light response in both eyes (constriction). Affected eye stimulated = no response/change

Normal near reflex

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26
Q

relative afferent pupil defect (what it is)

A

RAPD = objective sign of asymmetric lesion in anterior visual pathway

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27
Q

relative afferent pupil defect (cause)

A

incomplete optic nerve lesion or severe retinal disease (usu. optic nerve conduction defect)

NEVER due to a dense cataract

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28
Q

relative afferent pupil defect (signs)

A

Like an absolute afferent pupil defect but not as severe

Swinging flashlight test: both eyes constrict when light shone in normal eye. both eyes dilate when light shone in affected eye. Affected eye’s consensual response > direct response so affected eye responds as if the light is dimmer; termed pupillary escape

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29
Q

What is the near reflex?

A

Pupils constrict with convergence, dilate with divergence

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30
Q

What is the light-near dissociation?

A

normal near reflex but abnormal or sluggish light reflexes

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31
Q

If _____ reflex is normal, the ____ reflex will be normal (but the converse is not true)

A

light, near

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32
Q

Argyll Robertson pupil (causes, association)

A

neurosyphilis (tertiary syphilis)

Ocular assocations: interstitial keratitis

Systemic associations: (+) syphilis serology

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33
Q

Argyll Robertson pupil (signs)

A

Small irregular pupils that show light-near dissociation

Usually bilateral but may be asymmetrical

Poor reaction to light (constriction and dilation

Poor dilation with mydriatic

Normal constriction with convergence

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34
Q

pharmacological pupil defects (reflex responses, type)

A

abnormal light response

abnormal near response

(efferent defect)

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35
Q

pharmacological pupil can be ______ or _______

A

unilateral or bilateral

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36
Q
A

right pharmacological pupil

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37
Q

pharmacological pupil, unilateral, miosis -> what drug will cause this?

A

pilocarpine

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38
Q

What drug(s) will cause pharmacological pupil, unilateral, mydriasis?

A

Mydriacyl, tropicamide, cyclogyl, cyclopentalate

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39
Q

What drugs will cause bilateral pharmacological pupils, miosis?

A

Systemic drugs (8): caffeine, chloryl hydrate, chlorpromazine, histamine, MAO inhibitors, morphine, nicotine, opiates

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40
Q

What causes bilateral pharmacological pupil, mydriasis?

A

Systemic drugs: amphetamines, antihistamines, cocaine, benedryl, LSD, marijuana, tricyclic antidepressants

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41
Q

What is anisocoria?

A

Unequal pupil size; abnormal pupil may be smaller or larger

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42
Q

Anisocoria suggests …

A

Efferent (motor) defect but need to look at eyelid position and EOM

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43
Q

Anisocoria examination (2 main components)

A

Case Hx and ocular examination

44
Q

Anisocoria examination -> Case Hx questions

A
  1. Onset (may look at photographs)
  2. S/Sx? (Reduced VA, ptosis, EOM disorders, iris heterochromia)
  3. trauma? (esp to eye/head)
  4. eye drops/ointment?
  5. Syphilis?
45
Q

Anisocoria - ocular examination tests

A

Pupil assessment (light & near, RAPD)

Pupil size in light and dark conditions (anisocoria greater in light = larger pupil is abnormal; anisocoria greater in dark = smaller pupil abnormal)

Ptosis, ocular motility

Pupillary margin examination (slit lamp)

Pharmacological testing

46
Q

Cause of anisocoria, miosis (abnormal pupil constricted)

A

Unilateral use of green top (miotic) for glaucoma

Iritis

Horner’s syndrome

Argyll Robertson pupil

47
Q

What causes anisocoria, mydriasis (abnormal pupil is dilated)?

A

Unilateral use of red cap (mydriatic) by nurses, due to drugs, insecticides

Trauma (iris sphincter damage)

Tonic pupil (idiopathic = Adie’s)

CN3 palsy

48
Q

Anisocoria but difference in light and dark conditions is the same

A

Physiological pupil

49
Q

What is a 3rd nerve palsy?

A

Any interruption of the 3rd nerve pathway

50
Q

What muscles are functional in a 3rd nerve palsy?

A

Functional: SO (abduction, depression, internal rotation) and LR (abduction)

51
Q

What muscles aren’t functioning in a 3rd nerve palsy?

A

Non-functional: SR, MR, IR, IO, levator, sphincter

52
Q

Signs of a 3rd nerve palsy

A

Ptosis, mydriasis, cycloplegia, exotropia

-may see exotropia and depression in patients (despite SO have no depressor function in abduction)

53
Q

3rd nerve palsy effects on lids, primary gaze, abduction, adduction, elevation, depression

A

Lids: ptosis

Primary gaze: down and out no MR = XOT, wall eyed)

Abduction: normal (LR is functioning)

Adduction: limited (MR not functioning)

Elevation: limited (no SR or IO)

Depression: limited (no IR)

54
Q

3rd nerve palsy and normal pupil suggests … (cause, key features, and prognosis)

A

Microangiopathy (hypertension, diabetes)

Periorbital pain common and may be presenting sign in DM

Prognosis: usu. spontaneous recovery w/in 3 months

55
Q

3rd nerve plasy and dilated pupil suggests …. (cause, key features, prognosis)

A

Pupil involvement = Nerve compression (aneurysm, trauma)

Pain often presents with aneurysm

Life-threatening > requires immediate MRI and neurological examination

56
Q

What is Horner syndrome?

A

Oculosympathetic palsy; disruption of EFFERENT sympathetic pathway

57
Q

Is Horner syndrome congenital or acquired?

A

Can be either but recent onset (ie. acquired) is very suspicious

58
Q

Signs and symptoms of Horner syndrome?

A

Often asymptomatic

“Ptosis, miosis, anhydrosis” triad

  • Ptosis: upper lid droops, lower lid elevated
  • Miosis: pupil constricted on affected side
  • Anhydrosis: not sweating on affected side (bc external carotid artery plexus affected)

Iris heterochromia (for CONGENITAL only, lighter on affected side)

Pupils: light and near reflex normal, no RAPD, pathognomic dilation lag in dim light

59
Q

3rd nerve palsy may involve ____ system and Horner syndrome involves ____ system

A

parasympathetic, sympathetic

60
Q

Preganglionic vs postganglionic acquired horner syndrome etiologies

Implication for prognosis?

A

1st order and 2nd order are preganglionic

3rd order is postganglionic

Better prognosis is postganglionic (rather than preganglionic)

61
Q

Pathognomic sign of Horner syndrome?

A
  • Dilation lag in dim light
  • affected eye = slower dilation
  • anisocoria most obvious after 4-5 seconds; less obvious after 10-12 secs

(Also have normal light and near reflexes, no RAPD)

62
Q

Acquired horner syndrome: 3 types of etiology

A
  • 1st order: stroke, tumours
  • 2nd order: Pancost lung tumour, neuroblastoma (children)
  • 3rd order: cluster migraine, HZV, cavernous sinus tumour
63
Q

1st order Horner Syndrome etiology

A

(1st order = central neuron, preganglionic)

Stroke, tumour

64
Q

2nd order acquired Horner syndrome etiology

A

Tumours (lung carcinoma aka Pancost, thyroid/neck adenoma)

If arm pain, suspect Pancoast tumour (lung)

If child, suspect neuroblastoma

[2nd order runs from the spinal cord to the superior cervical ganglion]

65
Q

Relevant anatomy to Horner syndrome

A

The pupil is innervated by sympathetic and parasympathetic fibers. Pupillary dilation is mediated by a three- neuron sympathetic pathway that originates in the hypothalamus.

_1st order (central) neuron_: runs from **hypothalamus -\> cervical spinal cord** (C8-T2)
_2nd order neuron_: **spinal cord** -\> cervical sympathetic chain through brachial plexus, over pulmonary apex **-\> synapse in superior cervical ganglion** (near mandible angle, common carotid bifurcation)
_3rd order (postganglionic) neuron_: **superior cervical ganglion -\> iris dilator** muscle, Muller's muscle in upper and lower lid (travels on outside of internal carotid artery into the cavernous sinus. Here the oculosympathetic fibers join trigeminal V1 division to enter the orbit. The fibers (long ciliary nerve) innervate the dilator and Müller’s muscle)

Pupillary constriction is produced by parasympathetic (cholinergic) fibers that travel with the third cranial (oculomotor) nerve.

66
Q

3rd order acquired Horner syndrome etiology

A

Postganglionic (better prognosis)

Cluster migraine HZV, cavernous sinus tumour

67
Q

Horner Syndrome diagnosis (list the method(s))

A

2-10% cocaine test, bilaterally, 1gt OU: (+)ve confirms Horner syndrome

1% hydroxyamphetamine: locates lesions (1st, 2nd, or 3rd order)

Radiological work up: differentiate 1st and 2nd order

68
Q

How do you test for presence of Horner syndrome? Why do you use that particular test?

A

2-10% cocaine test, bilaterally, 1gt OU

Horner pupil dilates less than normal pupil bc no postganglionic neurotransmitters are being released

Cocaine only causes pupil dilation if norepineprhine is present/released at postganglionic nerve endings in the iris dilator muscle. Cocaine blocks reuptake of NE which leads to dilation of unaffected eye

69
Q

For Horner syndrome, what is the first test that you would use to localize the lesion?

A

1% hydroxyamphetamine (Paredrine) => test will differentiated pre-ganglionic from post-ganglionic

Test is done at least 24 hrs after cocaine test

1gt OU, repeat 1 minute later

Watch for dilation of suspected pupil after 30 minutes. If no dilation of suspected pupil = 3rd order (post-ganglionic).

Hydroxyamphetamine will not cause pupillary dilation if post-ganglionic pathway is disrupted

70
Q

For Horner syndrome, what is the second test that you would use to localize a lesion?

A

Radiological work up => differentatie between 1st and 2nd order defects (both are pre-ganglionic)

Will differentiated between internal carotid aneurysm (1st order) and Pancoast tumour (apical lung tumour, 2nd order)

71
Q

10% cocaine - pupil dilates

A

Dx: normal

72
Q

Cocaine 10% - eye does not dilate as much (impaired dilation)

A

Dx: Horner syndrome

73
Q

Hydroxyamphetamine 1% - eye dilates

A

Normal OR preganglionic Horner syndrome

74
Q

Hydroxyamphetamine 1% - eye does not dilate

A

Postganglionic Horner syndrome

75
Q

Mydriatic - eye does not dilate much (poor dilation)

A

Argyll Robertson pupil

76
Q

Mydriatic - eye dilates

A

Normal

77
Q

What is a tonic pupil?

A

Dilated pupil that reacts poorly to light and accommodation; shape often distorted

78
Q

Etiology of tonic pupils?

A

Dilated pupil with poor light response/accommodation due to a postganglionic lesion (denervation of parasympathetic supply to sphincter & ciliary muscle)

79
Q

Types/causes of tonic pupils

A

Trauma

Infection (Herpes Zoster)

Diabetes

Idiopathic (Adie’s)

80
Q

Tonic pupils are very sensitive to …..

A

Dilute cholinergic agents (ie. pilocarpine)

81
Q

Prevalence of Adie’s tonic pupil

A

~2 per 1000, usually young women (80%) with a Hx of mild URT infection (upper respiratory tract)

82
Q

Adie’s tonic pupil is associated with ….

A

Loss of deep tendon knee reflexes (sometimes)

83
Q

What is the cause of Adie’s tonic pupil and implications?

A

Damage to ciliary ganglion or postganglionic parasympathetic fibres

Heightened sensitivity to cholinergic agents (denervation supersensitivity) -> tonic pupils constrict to 0.125% pilocarpine (normal eye unaffected)

84
Q

What are the signs of Adie’s tonic pupil?

A

Unilateral, irregular, slightly dilated pupil

Poor light reflex (direct and consensual)

Impaired near reflex (slow convergence and accommodation; slow tonic re-dilation as Pt shifts gaze from near to far)

Unilateral blurred vision due to decreased accommodation (may req assymmetric reading adds)

Affected pupil becomes smaller over time (may eventually be smaller than the normal pupil, “little old Adie”)

85
Q

Adie’s tonic pupil - what is its reaction in bright light vs dim light?

A

Anisocoria greater in bright light than in dim (miosis is impaired bc this is a parasympathetic efferent defect)

86
Q

Adie’s tonic pupil - near reflex response?

A

Near reflex intact but slow (accommodative neurons re-innervate iris sphincter)

87
Q

0.125% pilocarpine added OU but only OD constricts

A

OD is Adie’s tonic pupil

88
Q

What is Tournay phenomenon?

A

Lateral gazes induce an enlarged pupil in abducting eye

89
Q

Pathophysiology of Tournay phenomenon

A

Anomalous innervation of the iris sphincter by the neurons intended for the ipsilateral medial rectus (co-innervation)

Inhibition of MR during lateral gaze thought to inhibit sphincter in abducting eye

90
Q

Tournay phenomenon - etiology, frequency, associations

A

Congenital

Rare

No known associations

91
Q

Signs of iris sphincter damage?

A

Hx of ocular trauma

Torn pupillary margin (traumatic mydriasis)

Iris transillumination defects

Hyphaema

92
Q

What is Hutchinson pupil (including key features)?

A

Affected pupil unresponsive to light, fixed, and widely dilated (other pupil contracts normally)

Due to a intracranial lesion (e.g. lesion compressing the 3rd nerve)

93
Q

Causes of Hutchinson pupil

A

Usually severe head injury

Also: stroke, brain tumour, abscess, edema, skull fracture (bilateral dilation)

94
Q

Pilocarpine 0.1% - eye constricts

A

Adie’s tonic pupil

95
Q

Pilocarpine 0.1% - no reaction (no constriction)

A

Normal

96
Q

Pilocarpine 0.5% - eye constricts

A

Not pharmacologically dilated

97
Q

Pilocarpine 0.5% - no constriction/reaction

A

Pharmacological dilation

98
Q

What is physiological anisocoria?

A

Bilateral pupil inequality

Small disparities are normal (in about ~20% of population)

99
Q

Signs of physiological anisocoria

A

Size difference usually <2mm; unlikely to see differences of 0.4mm or less

So, expect differences of 0.5mm-2mm

Pupil size disparity is the same in light and dark

Normal light reflexes, no RAPD, normal accommodation response

100
Q

anisocoria greater in light

A

larger pupil is abnormal

101
Q

anisocoria greater in dark

A

smaller pupil abnormal

102
Q

What is the Horner syndrome triad?

A

“Ptosis, miosis, anhydrosis” triad

Ptosis: upper lid droops, lower lid elevated
Miosis: pupil constricted on affected side
Anhydrosis: not sweating on affected side (bc external carotid artery plexus affected)

103
Q

What is unusual about the ptosis in Horner syndrome?

A

There is lower lid elevation (along with upper lid depression)

104
Q

What symptoms appear in Horner syndrome? (symptoms not signs)

A

Usually asymptomatic

105
Q

What other signs appear in Horner’s syndrome besides the triad? (2)

A

Iris heterochromia (for CONGENITAL only, lighter on affected side)

Pupils: (besides miosis) light and near reflex normal, no RAPD, pathognomic dilation lag in dim light

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