• The pupil is an rounded opening located in
the center of the iris that allows light to
enter the retina.
• Its function is to control the amount of light
entering the eye and it does this via
(mydriasis) under the influence of the
autonomic nervous system
The Pupil - Characteristics
Range of pupil diameters
Day light: 2.5 - 4.0 mm
Extremes: 1.3 - 10 mm
Anisocoria - unequal diameters.
Direct: light in OD
right pupil constricts
Indirect (consensual): light in OD
left pupil constricts
Near response: pupils constrict for near vision (due to
accommodation and convergence)
Drugs with autonomic actions:
Miotics: activate sphincter (PS) or block dilator (S)
Mydriatics: activate dilator (S) or block sphincter (PS)
• Congenital defects
(e.g. coloboma, aniridia and
polycoria, corectopia, congenital horners syndrom )
•Trauma : mydriasis or sphincter rupture D shaped pupil
in irridodyalisis and surgical trauma.
•Inflammatory: iridocyclitis miosis, Irregular narrow
pupil, Festooned pupil (effect of mydriatics in presence
of posterior synechiae).
•Angle closure glaucoma: A fixed vertically oval middilated pupil in association with severe pain, a red eye, a
cloudy cornea and systemic malaise suggests acute which
warrants immediate referral.
Systemic : Diabetis narcotics(morphine, pethidine)
mydriatics and miotics.
abnormalities of the Shape:
Aniridia - this is a bilateral condition arising from the abnormal
neuroectodermal development secondary to genetic mutation. It is
associated with glaucoma and a number of serious, systemic
(corectopia, ectopia pupillae) Ectopic (Misplaced) Pupils:
Isolated ectopic pupils may be inheritant
the pupils may be
displaced in any direction the pupils is frequently associated with
ectopia lentis, congenital glaucoma, microcornea, ocular coloboma,
and high myopia. Ectopic pupils also occur in some patients with
albinism and some patients with Axenfield Rieger anomaly.
acquired corectopia may occur in patients with severe midbrain
damag, ICE syndrome , posterior polymorphous corneal dystrophy.
Polycoria and Pseudopolycoria:
In true polycoria, the extra pupil or pupils are equipped
with a sphincter muscle that contracts on exposure to light. This is an
extremely rare congenital condition. This pseudopolycoria is passive
constriction, distortion, or even occlusion of the accessory pupil
when the true pupil is dilated (More commonly, pseudopolycoria
occurs as an acquired disorder from direct iris trauma including
surgery, photocoagulation, ischemia, or glaucoma or as part of a
degenerative process such as the ICE syndrome
Irregular pupil in a case of iridocyclitis
Angle closure glaucoma
Pupil in diabetes
Sluggishly reactive due to
Glycogen infiltration of spincter
Arteriosclerosis of radial iris vessels
In afferent (sensory) lesions, the pupils are
equal in size. Anisocoria (inequality of
pupillary size) implies disease of the efferent
(motor) nerve, iris or muscles of the pupil.
Adie’s Tonic Pupil
Dilated pupil; poor light response; better near response
Due to ciliary ganglion disease or short ciliary initially
paralyzes sphincter pupillae and may paralyze ciliary muscle,
causing failure of accommodation
Gradually accommodation returns (more fibers from ciliary
ganglion innervate near than light response)
Pupil sphincter response returns more slowly, and remains
sluggish to light and more responsive to near (accommodation)
Response tonically to dilute pilocarpine due to denervation
Dynamic Anisocoria - Adie’s Tonic Pupil (OS)
dilation lag (OS)
• Bilateral mid-dilated pupils that react
poorly to light but constrict normally with
convergence (i.e., not tonic). Associated
with eyelid retraction, supranuclear upgaze
paralysis, and convergence retraction
nystagmus. An MRI should be performed to
rule out pinealoma and other midbrain
Argyll Robertson pupil
• neurosyphilis, DM, encephalitis, MS and
• Asmall irregular pupil , anisocoria, lightnear dissociation: light reflex absent &near
is normal, poor dilatation in dark and
• Unilateral headache (cluster) or facial pain
in distribution of trigemial nerve
• Conjunctival hyperemia
Horner’s Syndrome (Oculosympathetic
Congenital Horner’s Syndrome
• Produces pupillary dilation by preventing
reuptake of norepinephrine
• Cocaine 10% (2 drops, 5 minutes apart)
• In order to act it require functioning
• Dilate normal pupil only
Mechanism of action
• α2 agonist with significant α1 effect
• Apraclonidine produces significant dilation
of the affected pupil, but the normal pupil
will fail to respond
• Dilates the pupil only in presence of endogenous
• 2 drops of 1% hydroxyamphetamine 2 days
after cocaine test.
– Forces norepinephrine from sympathetic nerve
• localization of Horner’s syndrome lesion
central or preganglionic
– No mydriasis
Requires postganglionic be intact
Adrinaline 1:1000 test In both eye:
• In preganglionic lesion→ both pupil not
dilate because adrinaline is destroyed by
• In postganglionic lesion → Horner`s pupil
will dilate because amine oxidase is absent.
Dilatation Lag Test
Demonstrates impaired sympathetic response of the
affected pupil with flash photography.series of 3
photographs were taken.
• The first was in room light with added light in one
eye from a penlight.
• The second photograph was taken in darkness, 4
to 5 seconds after the lights were turned off.
• the third, in darkness 10 to 12 seconds after the
lights were extinguished.
Horner’s pupil will lag behind in dilation, especially
at 4-5 seconds
Dilatation Lag Test
Pourfour de Petit Syndrome
This syndrome is the clinical opposite of
Horner syndrome. It represents
unilateral mydriasis, lid retraction, apparent
exophthalmos, and conjunctival blanching
Seen after trauma, brachial plexus
anesthetic block or other injury, and
• Useful in assessment of head injuries
• Stage1 : Ipsilateral pupil (on the side of
head injury shows contraction due to
irritation, Contralateral (normal) pupil –
• Stage2 : Ipsilateral pupil shows dilatation
due to paralysis , contralateral pupil
constricts (irritation spreads to normal side)
Stage3 : Both pupils dilate. Stage of
bilateral paralysis. To assess pupil
repeatedly is important, therefore
mydriatics should be avoided in case of
abnormally constricted pupil
– Unilateral use of a miotic.
– Iritis: Eye pain, redness, and anterior chamber
cells and flare.
– Horner syndrome:miosis ptosis anophthalmos.
– Argyll Robertson pupil:acc reflex preserved.
– Long-standing Adie pupil: The pupil is initially
dilated, but over time may constrict.
Hypersensitive to pilocarpine 0.125%.
– Pontine hge.
Abnormally dilated pupil
– Iris sphincter muscle damage from trauma:
Torn pupillary margin or iris transillumination
defects seen on slit-lamp examination.
– Adie (tonic) pupil.
– Third nerve palsy.
– Unilateral exposure to a mydriatic.