The pupil is a circular opening located in the center of the iris that controls the amount of light entering the eye to ensure optimal vision. Key characteristics of a normal pupil include being equal in size and round between both eyes. Abnormal pupils can be too small (miosis) or too large (mydriasis) and may be caused by medical conditions, drugs, or neurological disorders. Doctors examine the pupil's size, shape, equality, reaction to light, and accommodation to evaluate for any abnormalities.

1. PUPIL
Dr.Sandra Mosses
JR1M3

2.  aperture located in the centre of the iris that
allows light to enter the retina
 control the amount of light entering the eye
 ensure optimal vision for the lighting conditions
 pupils should be equal in size, round, regular,
centered in the iris and should exhibit specific
reflex responses PERRLA

3. Size
 normal –2-6 mm in diameter
 ordinary ambient light ---3-4 mm in diameter
Ambient
illuminatio
n
Para
Sympatheti
c
supply
Sympatheti
c
supply

4. PUPIL GAUGE

5. Miosis <2 mm
 Old age
 Hyperopia
 Alcohol abuse
 Neurosyphilis
 Diabetes
 Levodopa therapy
 Horner's syndrome
 Pontine hematoma
Spastic or irritative miosis-- spasm of
the pupillary sphincter
 Corneal/intraocular fbs
 Miotic drops
 Spasm of the near reflex
 Chronic anterior segment
ischemia
 Adie's pupil
Scarring miosis
 Iridocyclitis-- scarring bind the
pupil down to the cornea (anterior
synechia) or lens (posterior
synechia) and cause miosis and
pupillary irregularity
Paralytic miosis-- paralysis of the
Acquired miosis
ophthal
disorders

6. Mydriasis >6 mm
 anxiety, fear, pain
 myopia
 bilateral lesions of the retina /anterior visual
pathways
 midbrain lesions
 cardiac arrest
 cerebral anoxia
 terminal condition

7.  Large pupils were
once considered a
sign of youth and
beauty, and the
anticholinergic
belladonna (Ital. “fair
lady”) alkaloids were
named for their
ability to produce
this effect
 Persons with light
irises have larger
pupils than those

8. Effects of Drugs on the Pupil
 Atropine
 Homatropine
 Scopolamine
 Epinephrine/norepinephr
ine
 Phenylephrine
 Hydroxyamphetamine
 Cocaine
Anticholinergics/sympatho
 Pilocarpine
 Methacholine
 Muscarine
 Physostigmine/neostigmi
ne
 Opiates
 Ergot derivatives
Cholinomimetics/cholineste
MYDRIASIS MIOSIS

9. Shape
 round, with a smooth, regular outline
Abnormalities –
 iritis
 Synechia
 congenital coloboma (a gap in the iris)
 prior trauma
 iridectomy

10. Equality
 reactivity of the normal eye and the consensual light
reflex will ensure pupil size remains equal
 difference of 0.25 mm in pupil size is noticeable
 difference of 2 mm is considered significant
Physiologic anisocoria
 1 mm difference --15% to 20%
 degree of inequality remains about the same in light
and dark
 pupils react normally to all stimuli and to instilled
drugs

11. ANISOCORIA

12. TOURNAY ‘S PUPILLARY
PHENOMENON

13. eccentric pupil
spontaneous, cyclic
displacement of the pupil
from the centre of iris
• local eye disease
• Severe midbrain
disorders
CORECTOPIA IRIDIS (ectopia
pupillae, Wilson's sign)

14. MICROCORIA ---
MEGALOCORIA

15. POLYCORIA--multiple
pupils

16. Double pupil

17. Light
Reflex

19.  Always have the patient fix at a distance
 Normal pupillary light reflex -- brisk constriction
followed by slight dilatation back to an
intermediate state (pupillary escape)
 Escape may occur because of adaptation of the
visual system to the level of illumination
 Responses --prompt, sluggish, or absent, graded
from 0 to 4+

20. Accommodation Reflex
near response, near reflex, accommodation-
convergence synkinesis, near synkinetic triad
THICKENIN
G OF LENS
CONVER
GENCE
OF EYES
MIOSIS

22.  primary stimulus for accommodation is
blurring
 Without the near response, attempting to
focus on a close object would result in
blurred vision or frank diplopia
 Accommodation --contraction of the ciliary
muscle relaxes the zonular fibers,
permitting the lens to become more
convex because of its inherent elasticity---

23. Ciliospinal reflex
 consists of dilation of the pupil on painful
stimulation of the skin of I/L neck
 Local cutaneous stimulation (e.g., scratching
the neck)--activates sympathetics through
connections with the ciliospinal center at C8-
T2 --sympathetic nervous system—dilator
pupillae--I/L pupil dilate
 intact ciliospinal reflex is evidence of
brainstem integrity when evaluating a
comatose patient

24.  Oculosensory /oculopupillary reflex
consists of either constriction of the pupil or dilation
followed by constriction in response to painful
stimulation of the eye or its adnexa
 Piltz-Westphal reaction
pupils normally constrict on attempted lid closure
 Cochleopupillary reflex/Vestibulopupillary reflex
constriction followed by dilation occurs in response to a
loud noise/stimulation of the labyrinthine system
 Psychic reflex
dilate in response to fear, anxiety, mental concentration
because of sympathetic nervous system activity

25. Large Pupils
 pupillary parasympathetics occupy a position on the
dorsomedial periphery of the nerve as it exits the
brainstem
 compressive lesions -- affect the pupil (aneurysm)
 Ischemic lesions-- spare pupil (diabetic third nerve
palsies) because the periphery of the nerve has a better
vascular supply
 This rule is not absolute: pupil-sparing third nerve
palsies have been reported with aneurysms (in up to
10% of cases), as have diabetic palsies involving the
III rd CN palsy
Adie's tonic
pupil

27. PUPIL RULE ---
BARTON
Complete pupil sparing with
otherwise complete and
isolated palsy of CN III is
never due to an aneurysm

28. HUTCHINSON’S PUPIL
 Pupil is involved early
and prominently with
third nerve compression
due to uncal herniation

29. Cavernous sinus
lesions
 ocular sympathetics are involved
along with CN III
 pupil may be midposition
 compression of both CN III and the
pericarotid sympathetics, leaving the
pupil mid-size but unreactive
 should not be mistaken for pupil
sparing

30. Adie's (Holmes-Adie) tonic pupil
 Asymptomatic Young woman suddenly noticing
Unilaterally enlarged pupil
 Pupillary reaction to light absent
 Reaction to near slow but preserved
 Ciliary ganglion or short ciliary nerves or both
 Depressed or absent deep tendon reflexes,
particularly in the lower extremities
 Old adie's pupil --unilateral miosis

31. Small Pupils
HORNER'S
SYNDROME
ARGYLL
ROBERTSON PUPIL

32. HORNER’S SYNDROME [J. F.
Horner]
 Sympathetic dysfunction
Ptosi
s
Miosis Anhidrosis
Apparent
enophthalmo
s
Loss of the
ciliospinal reflex
Ocular
hypotony
Increased
amplitude
of
accommoda
tion
vasodilatio
n in
affected
distributio
n

33.  Small pupil dilates poorly in the dark
 Pupillary asymmetry greater in the
dark than in the light generally means
Horner's syndrome
 The pupil in Horner's syndrome not
only dilates less fully, it dilates less

34.  Ptosis of the upper lid due to denervation of Müller's
muscle is only 1 mm to 3 mm
 The lower lid is frequently elevated 1 mm to 2 mm
because of loss of the action of the lower lid accessory
retractor that holds the lid down (inverse ptosis)
 Resulting narrowing of the palpebral fissure causes
apparent enophthalmos
 Fibers mediating facial sweating travel up the external
carotid--lesions distal to the carotid bifurcation produce
no facial anhidrosis except for perhaps a small area of
medial forehead that is innervated by sympathetic fibers
traveling with the internal carotid

36. FIRST ORDER HORNER'S SYNDROME
 Interruption of the sympathetic pathways between
the hypothalamus and the spinal cord (Wallenberg's
syndrome)
SECOND ORDER HORNER'S SYNDROME
 2nd order neuron lies in the ciliospinal center at C8-
T2
 Lesion involving this portion of the pathway (e.g.,
syringomyelia, C8 root lesion)
THIRD ORDER HORNER'S SYNDROME
 third order neuron lies in the superior sympathetic

38. CAUSES OF HORNERS
SYNDROME
 Brainstem lesions (especially of the lateral
medulla)
 Internal carotid artery thrombosis or
dissection
 Cavernous sinus disease
 Apical lung tumors
 Neck trauma
 Cluster headache
 Isolated manifestation of syringomyelia

39. Behaviour of unequal pupils in light
& dark

40. Reverse Horner's syndrome
(Porfour du Petit syndrome)
 Unilateral mydriasis, facial
flushing and hyperhidrosis
 Due to transient sympathetic
overactivity in the early stages of
a lesion involving the sympathetic
pathways to one eye

41. Pharmacologic testing to assess
level of lesion
 Cocaine drops instilled into the eye can confirm
the presence of Horner's syndrome
 Cocaine blocks the reuptake of norepinephrine
from the nerve terminals, increasing its effect
 With Horner's syndrome of any type, there is
less norepinephrine being released, less
accumulates at the pupillodilator, and cocaine
will fail to dilate the affected pupil

42. Hydroxyamphetamine
 can distinguish a third order from other types of
Horner's syndrome
 release of norepinephrine, but only from intact nerve
endings
 If the third order neuron is intact, as with first or
second order Horner's syndrome, the pupil will dilate
in response to hydroxyamphetamine
 In a third order Horner's syndrome, there are no
surviving nerve endings in the eye to release
norepinephrine and the pupil will fail to dilate

44. Congenital Horner's syndrome
 may cause sympathetic heterochromia iridis
and other trophic changes of the head and
face
Pseudo-Horner's syndrome
 Thompson et al. described a group of patient's
with unilateral ptosis and miosis of unrelated
origin simulating oculosympathetic paresis,
 majority of patients had simple, physiologic
anisocoria accompanied by incidental ptosis
due to blepharochalasis

45. Argyll Robertson Pupil
 small (1 mm to 2 mm)
 irregular in outline
 light near dissociation --react poorly or not at all
to light, but very well to near
 Anterior visual pathway function must be
normal
 generally bilateral and symmetric
 lesion lies in the periaqueductal region,
pretectal area and rostral midbrain dorsal to the

46. Mechanism:
 Pupillary light reflex fibers enter the
dorsal brainstem
 Near response fibers ascend to the EW
nucleus from the ventral aspect
 Disorders that affect the dorsal rostral
brainstem may affect the light reaction but
leave the near reaction intact

47. CAUSES OF LIGHT NEAR
DISSOCIATION
 Neurosyphilis (mandate serological testing if present)
 Diabetic autonomic neuropathy (tabes diabetica)
 Myotonic muscular dystrophy
 Amyloidosis
 Adie's pupil
 Lyme disease
 Chronic alcoholism
 Chiasmal lesions
 Sarcoidosis
 Multiple sclerosis (MS)
 Aberrant regeneration of CN III

48. Afferent Pupillary Defect
 Key clinical technique in the evaluation
of suspected optic neuropathy
 detect a side-to-side difference even
when the lesion is mild and there is no
detectable difference in the direct light
reflex when testing each eye
individually

49. Swinging flashlight test

50.  OPTIC NERVE LESION--brain detects a relative diminution in light intensity
and the pupil may dilate a bit in response
 The pupil in the other eye dilates as well because the consensual reflex
constricting the pupil in the good eye is less active than its direct reflex
 On moving the light back to the good eye, the more active direct response
causes the pupil to constrict
 On moving back to the bad eye, the pupil dilates because the direct light
reflex is weaker than the consensual reflex that had been holding it down
 As the light passes back and forth, the pupil of the good eye constricts to
direct light stimulation and the pupil of the bad eye dilates to direct light
stimulation
 DYNAMIC ANISOCORIA
 weaker direct response or the paradoxical dilation of the light-stimulated
pupil is termed an afferent pupillary defect (APD), or Marcus Gunn pupil

51. Hippus / pupillary play/
athetosis
 Normal pupils may display constant, small amplitude
fluctuations in size under constant illumination
 no clinical significance, even when pronounced
 but can cause confusion in the evaluation of an
afferent pupillary defect
 Hippus is random; a true APD will be consistent over
multiple trials
 Pay attention to the first movement of the pupil--
consistently a dilation movement the patient has an
APD and not hippus

53. UNSUAL PUPILLARY
ABNORMALITIES
 Paradoxical pupil
 Constrict in darkness
 Congenital retinal and optic nerve disorders
 Mechanism is unknown
 Tadpole pupil
 Pupil intermittently and briefly becomes comma-
shaped

54.  Springing pupil
(benign, episodic pupillary dilation; mydriasis á bascule)
Intermittent, sometimes alternating, dilation of
one pupil lasting minutes to hours
Young, healthy women
Often followed by headache
 Periodic unilateral mydriasis migraine and as an
ictal phenomenon
 Scalloped pupils  familial amyloidosis
 Oval pupilsmajor intracranial pathology /may be a
transient phase in evolving injury to the third nerve
nuclear complex