PUPIL & IT’S
ABNORMALITIES
Dr M Kavitha
1st year Post Graduate
Ophthalmology

• 1.General Considerations
• 2.Embrology
• 3.Normal Pupillary Reflexes & it’s pathways
• 4.Morphological Abnormalities of PUPIL
• 5.ANISOCORIA
• 6.Abnormal Pupillary Reflexes

GENERAL CONSIDERATIONS
• The Pupil is an aperture located in the iris diaphragm of the eyes that
allows light to enter the RETINA.
• FUNCTIONS
• Regulates the amount of light entering the Retina.
• To some extent reduces Spherical and chromatic aberrations and
improves Visual acuity.
• Increases the Depth of Focus.
• Dilated pupil allows better visualization for Fundus Examination.

Embyology
• SPHINCTER PUPILLAE appears by 12th week of GA
• DILATOR PUPILLAE begins to form at 6th month of GA.
• Innervation to PUPIL do not occur before 31wks of GA.
• PARASYMPATHETIC INNERVATION to Sphincter pupillae starts at
Term.
• SYMPATHETIC INNERVATION to dilator pupillae starts only after birth.

Embyology
• PUPILLARY MEMBRANE is a solid sheet of Mesenchymal tissue composed of Ve
derived from ANTRRIOR CILIARY ARTERIES.
• Pupillary membrane is completely formed by 8th week of GA
• Pupillary membrane undergoes regression from 6th month of GA and completel
disappears by 8th month of GA.
• Failure of Resorption of Pupillary membrane leads to PERSISTANT PUPILLARY
MEMBRANE.

• RELATIVE ANATOMY
• The Pupil size is Controlled by the SPHINCTER PUPILLAE & DILATOR
PUPILLAE Muscles of IRIS which are derived from the
NEUROECTODERM and are controlled by Autonomic Nervous System
• Parasympathetics innervate Sphincter pupillae and mediates
PUPILLARY CONSTRICTION through release of ACETYLCHOLINE.
• Sympathetics innervate Dilator pupillae and produces PUPILLARY
DILATATION by release of NOREPINEPHRINE.

• NEED FOR EXAMINATION of PUPIL
• 1.Objective indicator of light input
• 2.Pupillary function is an important objective clinical sign in patients
with Visual loss & Neurological diseases.

SIZE OF PUPIL
• The size of pupil in the normal Adults
is between 3.0mm to 4.5mm
• Normal variations seen in pupillary size
in relation to age is
• Women>men
• Myopes>Hypermetropes
• Emotions,Psychological State
• Background illumination
• Constrict in bright light
• Dilate in dim light
• To keep light entering the visual system constant.

NUMBER & LOCATION
• Normally there is ONE PUPIL in each eye.
• Normal pupil is placed almost in the Centre of the iris ( slightly N
• Nasal).

NORMAL PUPILLARY REFLEXES
• 1.Light Reflex
• 2.Near Reflex
• 3.Darkness Reflex
• 4.Psychosensory Reflex
• 5.Cilio Spinal Reflex

LIGHT REFLEX
• When light is shown in one eye both
Pupils Constricts.
• DIRECT LIGHT REFLEX – Constriction of
pupil in the eye to which light is shown.
• INDIRECT / CONSENSUAL LIGHT REFLEX
Constriction of pupil in the opposite eye .

• Anatomy
• Light reflex is mediated by Retinal photoreceptors subserved by 4 neurons.
• 1.FIRST( SENSORY) Connects each RETINA with both PRETECTAL NUCLEI in
the Mid-range at the level of SUPERIOR COLLICULI.
• 2.SECOND(INTERNUNCIAL) Connects each PRETACTAL NUCLEUS with
• To both EDINGER WESTPHAL NUCLEI .
• This forms the basis for Consensual / INDIRECT light reflex.
• 3.THIRD(PREGANGLIONIC MOTOR) Connects Edinger Westphal nucleus to
CILIARY GANGLION.
• Parasympathetic fibres pass through Oculomotor nerve enters inferior division
reach ciliary ganglion via nerve to Inferior oblique muscle.
• 4.FOURTH(POST GANGLIONIC MOTOR) Leaves ciliary ganglion and passes in
short ciliary nerves intervals SPHINCTER PUPILLAE.

NEAR REFLEX
• Near Reflex is a SYNKINESIS rather than a True Reflex.
• Near Reflex gets activated when gaze is changed from a distant to
Near target.
• It comprises of 1.CONVERGENCE OF EYES
• 2.ACCOMODATION OF LENSES
• 3.MIOSIS OF PUPILS
• Near reflex pathway is located more ventrally than the pretectal
afferent limb of light reflex.

• FLOW CHART OF NEAR REFLEX

• PATH WAY OF
NEAR REFLEX

• DARKNESS REFLEX : When a person goes from lighted environment
to darkness Pupils dilate.
• Dilatation is due to 1.Abolition of Light Reflex with consequent
relaxation of Shincter pupillae.
2.Contraction of dilator pupillae supplied by
sympathetic nervous system

• PSYCHO SENSORY REFLEX :Refers to dilatation of pupil in response to
sensory and Psychic stimuli.
• Pupillary Dilatation is due to 1.Sympathetic discharge to
dilate pupillae
2.Inhibition of the parasympathetic
discharge to the Sphincter pupillae.
• This is not seen in Newborns
• Fully developed at 6months of age

• CILIOSPINAL REFLEX : Refers to Bilateral pupillary dilatation of 1-2mm
• As a result of painful stimuli over FACE,NECK or UPPER TRUNK.
• Reflex is prominent during Sleep or coma than during Wakefullness.
• This is useful to study the INTEGRITY OF SYMPATHETIC PATHWAYS.
• AFFERENT impulses reach CILIOSPINAL CENTRE OF BUDGE resulting in
Pupillary dilatation through EFFERENT SYMPATHETICS.
• This reflex is mediated at SPINAL LEVEL hence not very useful to
evaluate BRAIN STEM FUNCTION.

CONGENITAL & MORPHOLOGICAL
ABNORMALITIES OF PUPIL
• 1.ECTOPIC PUPIL : Pupil located at a location away from its normal
central location,usually associated with Ectopia lentis termed as
ECTOPIA LENTIS ET PUPILLAE
• 2.DYSCORIA : Abnormality in the shape of pupil ( normally ROUND)
• 3.POLYCORIA:More than one pupillary aperture in each eye
seen in ANTERIOR SEGMENT DYSGENESIS SYNDROME.
• 4.CORRECTOPIA: Displacement of pupil from it’s normal position
which was previously located at its normal position.

Coloboma of Iris Festooned pupil

signing

• Pupillary area Exihibits colour depending upon the condition of
structures located behind it.
• Normally – Greyish black
• Aphakia – Jetblack
• IMSC – Greyish white
• MSC – Pearly white
• HMC- Milky white
• Cataracta brunuscence- Brown
• Cataracta nigra- Brownish black

• LEUCOCORIA : White reflex in pupil
• Seen in Congenital cataract, Retinoblastoma,Retinopathy of
prematurity.

• YELLOW REFLEX : Pupil will be yellowish white semidilated ,non
reacting
• Seen in Retinoblastoma,Pseudogliomas
• Also known as AMAUROTIC CAT’S REFLEX

ANISOCORIA
• Unequal size of pupils with the difference in diameter of 0.3mm or
more is referred as Anisocoria.
• Clinical types :1.Physiologic anisocoria
2.Miosis of one pupil.
3.Mydriasis of one pupil

Physiologic Anisocoria
• Also referred as Central/simple/ essential Anisocoria.
• The most common cause of unequal pupil size is central anisocoria.
• Occurs in 20% of normal individuals.
• Minimal anisocoria <0.4mm
• Usually not associated with any other ocular abnormality.
• Both Pupils react well to light
• Normal dilatation in dark ( no dilatation lag)
• Equal dilatation of both Pupils with topical cocaine.

• Pathological anisocoria Refers to difference in size of >2mm is a sign
of AUTONOMIC dysfunction.
• Anisocoria indicates an abnormality if EFFERENT PATHWAY( MOTOR)
and never due to Optic nerve lesions / AFFERENT PATHWAY (
SENSORY) defects.

• A pupil with a brisk sustained light reflex is a normal pupil
• ANISOCORIA same in bright / dim light is Physiological .
• ANISOCORIA increasing in bright illumination : The larger pupil is
abnormal with Parasympathetic palsy.
• ANISOCORIA increasing in dim illumination : The smaller pupil is
abnormal with a Sympathetic palsy.

MIOSIS OF ONE PUPIL
• Seen in
• Effect of local miotic drugs parasympathomimetics
• Systemic morphine effect
• Iridocyclitis (narrow,irregular,non reacting pupil)
• Horner’s syndrome
• Head injuries(pontine hemorrhages)
• Senile rigid miotic pupil
• During sleep

Mydriasis of one pupil
• Effect of topical Sympathomimetics
• Sphincter damage( ACUTE congestive glaucoma)
• Internal opthalmoplegia
• 3rd nerve Paralysis
• Belladona posing.

• Physiological conditions related To Normal
pupil
Pupillary unrest: Refers to constant fluctuation in pupillary diameter
under normal environmental conditions.
• Influenced by emotional stress ,illumination.
• Detected on inspection of magnified image of pupil
• Hippus: Refers to intermittent ,synchronous ,rhythmic contraction &
dilatation of Pupils that measures 1mm or more.
• Detected on visual inspection without magnification.

• Tournay‘s phenomenon: Refers to dilatation of pupil in the abducting
eye on extreme lateral gaze.
• Present in small% in Normal people , not associated with disease.
• Hypothesis says that Results from Mechanical Traction caused by
movement of globe that stimulates long ciliary nerves in abduction &
short ciliary nerves in adduction..
• Coinnervation of Iris sphincter & Medial Rectus muscle with both
being inhibited in abduction results in Dilatation in abduction.

ABNORMALITIES OF PUPILLARY REFLEXES
• 1.AFFERENT PATHWAY DEFECTS
• 2.EFFERENT PATHWAY DEFECTS
• 3.PUPILLARY LIGHT NEAR DISSOCIATION
• 4.SYMPATHETIC PARESIS

AFFERENT PATHWAY DEFECTS
• 1.ABSOLUTE AFFERENT PATHWAY DEFECT(APD/TAPD)
• Also termed as TOTAL AFFERENT PATHWAY DEFECT / AMAUROTIC PUPIL
• CAUSES: Complete Optic nerve / Retinal lesions
• Characteristics: 1.The involved eye is completely blind
2.Both pupils are equal in size.
3.When affected eye is stimulated by light neither
pupil reacts.
4.When NORMAL eye is stimulated both the Pupils react
normally
5.Near Reflex is normal in both the eyes.

• 2.RELATIVE AFFERENT PATHWAY DEFECT (RAPD)
• Also termed as MARCUS GUNN PUPIL
• Causes: Incomplete Optic Nerve lesions or Severe Retinal Diseases
• RAPD is never occurs due to a DENSE CATARACT.
• Characteristics: Pupils Respond WEAKLY on Stimulation of DISEASED
EYE & BRISKLY to that of NORMAL EYE.
• The pupillary reaction to light obtained through the impaired optic
nerve has a greater degree of REDILATATION than Normal.
• This phenomenon is brought out clearly by SWINGING FLASHLIGHT
TEST.

SWINGING FLASHLIGHT TEST

• The Patient is asked to fix at a distant target in a darkened room
• The Examiner shines a bright light into normal eye
• The Examiner observes for Speed & Extent of Constriction.
• The ipsilateral pupil constricts due to DIRECT LIGHT REFLEX.
• The contralateral pupil also constricts due to CONSENSUAL LIGHT REFLEX.
• Now the Examiner moves light quickly into another eye(with in 1-3secs)
• Because of impaired nerve transmission The EW Nucleus receives fewer
light elicited impulses and exerts less parasympathetic tone(as if eye is
exposed to dim light) resulting in Pupillary dilatataion instead of
Constriction.
• This paradoxical response is called MARCUS GUNN REACTION or MARCUSS
GUNN PUPIL.

GRADING OF RAPD
Grade 1+: A weak initial pupillary constriction followed by greater
redilation
Grade 2+: An initial pupillary stall followed by greater redilation
Grade 3+: An immediate pupillary dilation
Grade 4+: Immediate pupillary dilation following 6 sec illumination
Grade 5+: Immediate pupillary dilation with no constriction at all

• Swinging flashlight test can be performed even in the presence of
CORNEAL OPACITY,3rd NERVE PALSY& ATROPINISED PUPILS.
• Thus test is not useful in SYMMETRICAL BILATERAL OPTIC NERVE
LESIONS.

• 3.WERNICKE’S HEMIANOPIC PUPIL
Seen in the lesions of OPTIC TRACT
• Light reflex is absent ( both direct & indirect) when light is thrown on
temporal half of retina on affected side and Nasal half of retina on
opposite side.
• Light reflex is present when Light is thrown on Nasal half on affected
side and Temporal half on Normal side.

EFFERENT PUPILLARY PATHWAY DEFECTS
• CHARACTERISTICS:
• 1.Absence of both Direct & Consensual light reflexes on the affected
side.
• 2.Presence of both direct & Consensual light reflexes on the normal
side.
• 3.Absence of Near reflex on affected side.
• 4.Pupil will be FIXED & DILATED on affected side

• COMMON CAUSES
• 1.Brainstem lesions at level of Superior colliculus
• 2.Fasicular 3rd nerve lesions
• 3.Lesions in CILIARY GANGLION
• 4.Iris damage secondary to Previous surgeries
• 5.Inadvertent exposure to Mydriatics such as Atropine.

ADIE’S TONIC PUPIL
• Caused by DENERVATION of postganglionic supply of the Sphincter
pupillae and ciliary muscle which may follow viral illness .
• Usually UNILATERAL
• Affects Healthy young WOMEN more often than MEN
• Associated with absent knee jerks.
• Affected pupil is large and irregular.
• The light reflex is absent or slow.
• Near reflex is slow and tonic.
• Accomadative paresis.

• OCULOMOTOR NERVE PALSY
• Pupil is mid dilated and non reacting to light.
• No Constriction with 0.125% pilocarpine but constricts with 1%
pilocarpine.
• Look for other signs of 3rd nerve palsy like ptosis,deviation of eyeball.

• PHARMACOLOGICAL MYDRIASIS
• Widely dilated pupil (10-12mm) ( mid dilated in Tonic pupil & TNP)
• Dilatation is with Adrenergics .
• Blanched Conjunctival vessels.
• Residual light Reaction.
• Upper lid retraction ( mullers muscle stimulated)
• No Constriction with either 0.125% or 1% pilocarpine.

PUPILLARY LIGHT NEAR DISSOCIATION.
• Refers to a situation in which Pupillary light reaction is absent and Near
reaction is present.
• CAUSES:
1. Bilateral Complete AFFERENT PATHWAY DEFECT – Total RD or Bilateral
Optic atrophy.
2. Mid brainlesions:The light reflex pathway can be affected at pretectal
area sparing Near reflex pathway situated More VENTRALLY. Like
Perinaud syndrome,vascular lesions ,Encephalitis and demyelination.
3. Third nerve palsy with aberrant regeneration of Medial Rectus
innervation to the Sphincter innervation pathway.( Pseudo ARP)
4. Ciliay ganglion or short ciliary nerve lesions with aberrant regeneration
of accomodation impulses into sphincter pupillae ( tonic pupil)
5. Peripheral neuropathic like Diabetes,Alcoholism,Amyloidosis etc.

Argyll Robertson pupils
• It was originally described by
Dr Douglas Argyll Robertson.
• It is usually Bilateral,miotic,with
Irregular margins and asymmetrical
in both Size &response
to light & near reflex.
• Light Reflex is Absent ,
but Accomadation reflex is present.
• Pupils dilate very poorly with
mydriatics.
• Once commonly seen in
Tertiary syphilis especially in Tabes dorsalis..

OCULO SYMPATHETIC PATHWAY
• Anatomy : SYMPATHETIC supply involves 3 neurons
• 1.First( Central):Starts in Posterior Hypothalamus and descends down the
brain stem uncrossed and terminates in CILIOSPINAL CENTRE OF BUDGE in
the infero Medial horn of Spinal cord between C8 & T2.
• 2.Second(Preganglionic):Passes from cilio Spinal centre to Superior cervical
ganglion in neck. Through it’s long course it is closely related to the apical
pleura.(may get damaged in bronchiogenic ca,injured in neck surgeries)
• 3.Third( postganglionic):Ascends along internal carotid artery to enter
Cavernous sinus where it joins ophthalmic division of Trigeminal nerve.
• SYMPATHETIC fires reach the ciliary body & dilator pupillae via Nasociliary
nerve & long ciliary nerves.

HORNER SYNDROME
Also termed as OCULO SYMPATHETIC PALSY
Usually due to ipsilateral interruption of Sympathetic
outflow to the head & neck.
Majority of the cases are UNILATERAL.
BILATERAL involvement includes CERVICAL SPINE
INJURIES,AUTONOMIC DIABETIC NEUROPATHY.
PAINFUL HORNER Specially of acute onset should raise
the possibility of CAROTID DISSECTION.

• CHARACTERISTICS :
• PTOSIS: Mild to moderate ptosis occurs duets Paralysis of MULLER’S
muscle of upper eyelid.
• Inverse ptosis Elevation of inferior eyelid due to weakness of inferior
tarsal muscle.
• Miosis: Due to unopposed action of sphincter pupillae following
Paralysis of dilator pupillae.
• Pupillary reactions are Normal to light and near.
• Dilatation lag: When light is turned off Horner pupil dilates more
slowly than normal pupil because it lags the pull of dilator pupillae.

• Facial anhydrosis: Reduced sweating on the ipsilateral face and neck
is characteristic of postganglionic Horner syndrome.
• Heterochromia irides:When the sympathetic ocular innervation is
interrupted early in life ( congenital Horner syndrome) the pigment of
Iris stroma fails to develop producing heterochromia irides.

Localizing the lesions in HORNER SYNDROME
• 1.Central Horner syndrome: Occurs due to lesions located from
Hypothalamus to ciliospinal centre of budge.
• Causes : Brainstem vascular lesions ,demyelination tumors,
syringomyelia,SC lesions at C8-T2
• Associated signs & symptoms :
• Hypothalamus signs like DI,Altered sleep patterns
• Brainstem signs like Vertigo,,sensory deficits,anhydrosis of body.
• Signs of Cervical cord disease.

• 2.Preganglionic Horner syndrome:Occurs due to lesions located from
C8 – T2 of Spinal cord to the course of Preganglionic fibres to superior
cervical ganglion.
• Causes: Pancoast’s tumor of lung ,Carotid & aortic aneurysms,lesions
in neck ( trauma/ surgery)
• Anhydrosis involves face & neck.
• Brachial plexus palsy may be associated.
• Vocal cord palsy due to phrenic nerve palsy.

• 3.Postganglionic Horner syndrome: due to lesions in the course of
post ganglionic fibres.
• Causes:
• Ipsilateral vascular Headaches.
• Head injury ,intra aural or retroparotid trauma causing damage to
carotid sympathetic plexus.
• A tumor of middle cranial Fassa or cavernous sinus may involve
parasellar cranial nerves and effect the sympathetic fires of the eye.

Pharmacological tests employed to localize
Horner syndrome
• COCAINE TEST:
• It prevents the reuptake of nor epinephrine at neuromuscular junction.
• When 4% cocaine is instilled in both the eyes the normal pupil will dilate
but Horner pupil will not because in Horner there is no NE being secreted.
• All Horner’s pupil irrespective of location of pathway defect will dilate
poorly to cocaine.
• Hence Cocaine helps in establishing the Diagnosis of sympathetic
denervation and not in localizing the site of lesion.

• HYDROXYAMPHETAMINE TEST:
• The Hydroxyamphetamine acts by releasing norepinephrine from the
postganglionic nerve endings at the dilator pupillae.
• When 10% drops of this drug are instilled into both eyes, in a patient
with preganglionic lesion both Pupils will dilate where as in
postganglionic lesions Horner pupil will not dilate.

• ADRENALINE TEST:
• When Adrenaline 1in 1000 is instilled in both the eyes the horners
pupil due to postganglionic lesion dilates more than the normal pupil
does because of denervation supersensitivity.

PUPILS IN EMERGENCY ROOM
• Head injury/ unconcious patient:
• 1.Normally reacting equal sized pupil :Reassuring sign ,no
intracranial pathology ,look for metabolic causes.
• 2.Unequal pupils:Herniation of temporal lobe stretching 3rd CN
• 3.Bilateral dilated pupils:Tentorial Herniation, chances of recovery is
poor.
• 4.Bilateral pinpoint pupils:indicates pontine hemohhage