PUPILShruthi.s.jayaraj ,53rd

PUPIL

• aperture of the diaphragm of eye (iris) that allows light to enter the retina

FUNCTION• Controls amount of light entering the eye –

influence of ANS

Not all animals have circular pupil !!

• Pupils are controlled by 2 muscles of ectodermal origin –

1. Sphincter pupillae2. Dilator pupillae

• Circular fibres – parasympathetic supply – miosis

• Radial fibres – cervical sympathetic nerves – mydriasis

BALANCE OF TONE BETWEEN THE 2 ANTAGONIST MUSCLES MAINTAIN THE NORMAL PUPIL SIZE

• TONE OF SPHINCTER MUSCLE > TONE OF RADIAL MUSCLE (keeps the pupil slightly contracted )

• Pupils are equal normally on both sides unequal anisocoria

note1. normally there is one pupil. More than 1 pupil

is called polycoria

2.Pupil location almost central,slightly nasal..eccentric pupil is called correctopia

• Pupil size varies depending on the background illumination (2-3 mm normally)

• Diameter affects the type of image formed

Note the size,shape & contour of the pupil.then test for reflexes

PUPILLARY REFLEXES

PUPILS PARTICIPATE IN SEVERAL REFLEXES

• LIGHT REFLEXES – DIRECT,INDIRECT

• NEAR REFLEX

• PSYCHOSENSORY REFLEX

Keep in mind!!

• Illumination of examination room should be low

• Patient should look into the distance• Light used should be focussed & bright

• DIRECT & INDIRECT When light is shone in one eye,both the pupils

constrict.. Constriction of pupil to which light is shone is

direct light reflex and that of other is consentual ( indirect ) light reflex.

• Using a bright focussed light• In a dark room• Finer examination – slit lamp

Swinging flashlight test

• If both optic nerves are intact, both pupils will be tightly constricted

(direct’ magnitude = concensual)

If one optic nerve damaged,both pupils dilate on showing the light to the diseased eye.

on swinging back to normal side,both pupils constrict

• The dilatation or escape that occurs is called MARCUS GUNN PUPIL or AFFERENT PUPILLARY DEFECT.

NEAR REFLEX

OCCURS ON LOOKING AT A NEAR OBJECT. IT HAS 2 COMPONENTS : CONVERGENCE REFLEX (contraction of pupil on convergence) ACCOMODATION REFLEX (constriction of pupil on viewing a near target)

Convergence reflex

Accomodation reflex

PSYCHOSENSORY REFLEX

Refers to the dilatation of pupil in response to sensory and psychic stimuli

Complex, mechanism still not elucidated

• Light reflexes • Near reflex OF PUPIL• Psychosensory reflexes

PUPILLARY PATHWAY

SHORT CILIARY NERVES

N.TO INFERIOR OBLIQUE

Pupillary pathway

LESIONS IN THE PUPILLARY PATHWAY

OPTIC NERVE

1.OPTIC NERVE

• Abolition of direct reflex on affected side & consentual on opposite side

amaurotic pupil

MEDIAL CHIASMA

• Medial chiasma

bitemporal hemianopic paralysis

LATERAL CHIASMA

lateral chiasma

binasal hemianopic paralysis

OPTIC TRACT

• OPTIC TRACT

CONTRALATERAL HEMIANOPIC PARALYSIS (WERNICKE PARALYSIS) NO LIGHT REFLEX WHEN LIGHT IS THROWN ON

TEMPORAL HALF OF RETINA OF AFFECTED SIDE & NASAL HALF OF OPPOSITE SIDE

PROXIMAL PART OF OPTIC TRACT

• LESION OF PROXIMAL PART OF OPTIC TRACT – NORMAL PUPILLARY REACTIONS

IN THE REGION OF BRACHIUM &

TECTUM

CONTRALATERAL HEMIANOPIC PARALYSIS

CENTRAL DECUSSATION

• BILATERAL REFLEX PARALYSIS• INACTIVITY TO LIGHT REFLEX WITH

RETENTION OF NEAR REFLEX !!

ARGYLL ROBERTSON PUPIL

ARGYLL ROBERTSON PUPIL

• Pupil slightly smaller in size• Near reflex present but Light reflex absent i.e

there is light near dissociation• Both pupils are involved ,dilate poorly with

mydraiatics• Hallmark of tertiary syphilis (neurosyphilis)

B/W DECUSSATION & CONSTRICTOR

CENTRE – UNILATERAL ARP

PARTIAL LESION

• Ipsilateral abolition of direct reflex,with retention of indirect

• Retention of both contralaterally

NUCLEAR /EXTENSIVE

SUPRANUCLEAR LESION

Ipsilateral absolute pupillary paralysis

3RD NERVE

Ipsilateral absolute pupillary paralysis

CILIARY GANGLION

Lesion at ciliary ganglion

• Light reflex absent,retention of near reflex (very slow) and tonic

ADIE’S TONIC PUPIL

Adie’s pupil

Affected pupil is larger Usually unilateral a/w absent knee jerk ( HOLMES ADIE SYN) young women

• adies’s pupil constricts with weak pilocarpine (.125 %) while normal pupil does not

denervated iris sphincter is supersensitive to topical parasympathomimetics

OTHER CONDITIONS AFFECTING PUPILS….

Ophthalmoplegia interna

• d/t lesion in 3rd nerve nucleus• paralysis of both sphincter pupillae & ciliary

ms• Dilated,immobile pupils• Meningitis,encephalitis,cerebral syphilis,

trauma affecting 3rd nerve and ciliary ganglion etc

Unilateral dilatation may result from irritation of cervical

symapthetic nerves(swollen lymph nodes,cervical rib,apical

pneumonia,meningitis affecting lower cervical &upper thoracic ventral roots..)

IRRITATIVE DILATATION EVENTUALLY LEAD TO CONSTRICTION FROM

SYMPATHETIC PARALYSIS

When all sympathetic function on one side is lost,it result in

• miosis,• slight enophthalmos horner syndrome• ptosis • anhydrosis on affected side

HORNER’S

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