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Clinical testing pupils
Pupil size and reactivity are tested clinically to evaluate the eye and brain. The normal pupil constricts to light (direct and consensual response) and accommodation. Pupil size is controlled by the iris sphincter and dilator muscles innervated by the parasympathetic and sympathetic nervous systems. Pupillary reflexes like the light and accommodation reflexes are tested to localize lesions. Abnormal pupil size or reactivity can indicate conditions like Horner's syndrome or third nerve palsy. An afferent pupillary defect detected by the swinging flashlight test indicates optic nerve dysfunction. Pharmacologic testing can further localize lesions in the pupillary pathway.
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Clinical testing pupils
- 1. Clinical Testing: Pupils Dr.Roopchand.PS SeniorResident Academic Department of Neurology
- 2. Introduction: • The normalpupil 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)
- 3. • The sizeof 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.
- 4. Retina Optic tract Pretectal nucleus Edinger–Westphal nucleus oculomotor nerve ciliary ganglion Ciliarymuscles and constrictor pupil
- 6. 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.
- 8. Pupillary Reflexes: • LightReflex – Constriction of pupils in response to light. • Accomodation Refelx
- 9. 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.
- 10. • Can berecorded : 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
- 11. Other reflexes: • Ciliospinalreflex: 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.
- 12. Large pupils: • 3rdnerve 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.
- 13. • 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.
- 14. Small Pupils: • Pilocarpineeye drops, opiate • Horner's syndrome. • Neurosyphilis.
- 15. Horner's syndrome: • Ptosis –Denervation of mullers muscles • Miosis – Denervation of dilators • Anhydrosis – Sympathetic denervation • Apparent enophthalmosis – Narrowing of palpebral fissure • Absent ciliospinal reflex.
- 16. • Causes: – Brainstem lesions • Lat. Medulla – Cluster headache – IC thrombosis/ dissection – Cavernous sinus disease – Apical lung tumour – Neck trauma – Syringomyelia
- 17. • Porfour dupetit: reverse hornor’s – Unilateral mydriasis – Facial flushing – Hyperhydrosis – Transient sympathetic over activity – Early lesions involving sympathetic pathway to one eye.
- 18.
- 19. Pharmacologic Testing: • Cocaine •Hydroxyam phetamine First order • No response • Dilates Second order • No response • dilates Third order • No response • No response
- 20. 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
- 21. Abnormal Reaction: • Diseaseof 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).
- 23. 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
- 24. • The reactionis 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
- 25. Grading of anAfferent 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
- 26. • 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.