Clinical testing pupils

Clinical Testing: Pupils

Dr.Roopchand.PSSenior Resident AcademicDepartment of Neurology

Introduction:

• The normal pupil size in adults varies from 2 to 4 mm in diameter in bright light to 4 to 8 mm in the dark.

• They constrict to direct illumination (direct response) and to illumination of the opposite eye (consensual response).

• The pupil dilates in the dark.• Both pupils constrict when the eye is focused

on a near object (accommodative response)

• The size of the pupil is controlled by– the circumferential sphincter muscle found in the

margin of the iris• innervated by the parasympathetic nervous system

– iris dilator muscle, running radially from the iris root to the peripheral border of the sphincter.• iris dilator fibers contain α-adrenergic sympathetic

receptors

• Function : control the amount of light entering eyes for optimal vision.

• Hippus: constant small amplitude fluctuation of pupil under constant illumination.

Retina

Optic tract

Pretectal nucleus

Edinger–Westphal nucleus

oculomotor nerve

ciliary ganglion

Ciliary muscles and constrictor pupil

Observe for:

• SIZE:– Pupil gauge or millimeter ruler.– Size < 2mm: miotic– Size > 6mm : dilated

• SHAPE:– Round, smooth, regular outline.

• EQUALITY:– Difference of 0.25mm: noticeable, >2mm

significant.– 15-20% have physiological anisocoria.

• POSITION:– Corectopia: eccentric pupils.

Pupillary Reflexes:

• Light Reflex– Constriction of pupils in response to light.

• Accomodation Refelx

The Light Reflex:

• Tested in each eye individually• Patient fixing at a distance• Light shown to the eye obliquely.• Cover uncover thechique– Uses ambient light

• Normal response: brisk constriction -> slight dilatation back to an intermediate state.

• Can be recorded : prompt, sluggish, absent– Graded 0 to 4+

• THE ACCOMMODATION REFLEX:– Relax accommodation by gazing a distant object– Shifting gaze to some near object.– The primary stimulus for accommodation is

blurring.– Response: accommodation, convergence, miosis

Other reflexes:• Ciliospinal reflex: dilation of pupil on pain ful

stimulation of ipsilateral neck.• Occulosensory or occulopupillary reflex:

constriction or dilation followed by constriction on painful stimuli to eye or its adnexa.

• Plitz – Westphal reaction.• Cochleo pupillary reflex & vestibulopupillary

reflex.• Psychic reflex.

Large pupils:

• 3rd nerve palsy.– With pupil sparing– With predominant pupil involvement.– Mid dilated unreactive pupil.

• Adie’s pupil.– Slow response to light and removal of illumination– Lesion at ciliary ganglion/ short ciliary nerves– Denervation supersensitivity.– Old adie’s pupil: unilateral miosis.

• Tectal pupils: large pupils with light near dissociation.– seen in lesions affecting the upper midbrain.

• The variably dilated, fixed pupils reflecting midbrain dysfunction in a comatose patient carry a bleak prognosis.

• Acute angle closure glaucoma: dilated poorly reacting pupils– Cloudy cornea.

Small Pupils:

• Pilocarpine eye drops, opiate• Horner's syndrome.• Neurosyphilis.

Horner's syndrome:• Ptosis– Denervation of mullers muscles

• Miosis– Denervation of dilators

• Anhydrosis– Sympathetic denervation

• Apparent enophthalmosis– Narrowing of palpebral fissure

• Absent ciliospinal reflex.

• Causes: – Brain stem lesions• Lat. Medulla

– Cluster headache– IC thrombosis/ dissection– Cavernous sinus disease– Apical lung tumour– Neck trauma– Syringomyelia

• Porfour du petit: reverse hornor’s– Unilateral mydriasis– Facial flushing– Hyperhydrosis– Transient sympathetic over activity– Early lesions involving sympathetic pathway to

one eye.

Localizing lesion:

Pharmacologic Testing:

• Cocaine• Hydroxyam

phetamine

First order• No

response• Dilates

Second order• No

response• dilates

Third order• No

response• No

response

Argyll Robertson Pupil:

• Small irregular pupil having light near. dissociation.

• React poorly to light.• Normal near response.• Neurosyphilis.• Lesion in periaqueductal region, pre tectal,

rostral midbrain

Abnormal Reaction:

• Disease of the retina does not affect pupil reactivity.

• Cataracts and other diseases of the anterior segment do not impair light transmission.

• Because of the extensive side-to-side crossing of pupillary control axons through the posterior commissure, light constricts not only the pupil stimulated (the direct response) but also its fellow (the consensual response).

Afferent Pupillary Defect:• The status of the light reflex must be judged

by comparing the two eyes.• Indicator of optic nerve function• Swinging flashlight test: light is held about 1 in

from the eye and just below the visual axis; the light is rapidly alternated.– The examiner attends only to the stimulated eye.– Comparing the amplitude and velocity of the

initial constriction in the two eyes

• The reaction is relatively weaker when the bad eye is illuminated.

• The brain detects a relative diminution in light intensity and the pupil may dilate a bit in response.

• Bring out the dynamic anisocoria.• The weaker direct response or the paradoxical

dilation of the light-stimulated pupil is termed an afferent pupillary defect (APD), or Marcus Gunn pupil

Grading of an Afferent Pupillary Defect:

• Trace APD: pupil that has an initial constriction, but then it escapes to a larger intermediate position than in the other eye.

• 1 to 2+ APD: no change in pupil size initially, then dilation.

• 3 to 4+ APD: immediate dilation of the affected pupil.

• Placing neutral density filters over the good eye

• Paradoxical pupils: constrict in darkness– congenital retinal and optic nerve disorders.

• Springing pupil: intermittent, sometimes alternating, dilation of one pupil lasting minutes to hours seen in young, healthy women, often followed by headache.

• Tadpole pupil: pupil intermittently and briefly becomes comma-shaped because of spasm involving one sector of the pupillodilator

• Scalloped pupils: occur in familial amyloidosis• Corectopia iridis: spontaneous, cyclic displacement

of the pupil from the center of the iris.– seen in severe midbrain disease.

Thank You