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