Pupils PPO2 Past Paper 2024 PDF

PUPILS Ariette Acevedo, O.D. PPO2 OBJECTIVES Pupillary Pathway Anatomy  Efferent  Afferent Pupil Evaluation     Efferent Testing Afferent Testing Near/Accommodative Testing Interpretation of results Pupillary Abnormalities  Diagnosis  Management PUPIL Pupil functions:  Aid in light control...

PUPILS Ariette Acevedo, O.D. PPO2 OBJECTIVES Pupillary Pathway Anatomy  Efferent  Afferent Pupil Evaluation     Efferent Testing Afferent Testing Near/Accommodative Testing Interpretation of results Pupillary Abnormalities  Diagnosis  Management PUPIL Pupil functions:  Aid in light control  Depth perception  Improving image quality The pupil is an objective indicator of the amount of light transduction by the visual system.  The pupil can be used to monitor retinal light sensitivity  In clinical settings the amount of pupil constriction to a light stimulus or the steady-state diameter of the pupil under constant illumination can reflect the health of the retina or optic nerve It is important to evaluate pupils since they provide great information regarding neurologic functions  Pupillary abnormalities can be the only sign of a dysfunction of the eye or the brain Pupil response is mediated by the sympathetic and the parasympathetic system PUPIL SIZE Pupil size is determined by a balanced tone in the autonomic nervous system (ANS).  Afferent and Efferent  Afferent: carries sensory information towards the CNS.  Efferent: carries motor impulses from CNS to the muscles. IRIS MUSCLES 2 agonist muscles in the iris:  Sphincter: Miosis, constriction  Under parasympathetic innervation  Dilator (radial): Mydriasis, dilation  Under sympathetic innervation AFFERENT PATHWAY Cranial Nerve II (Optic Nerve) perceives light and takes the message to the brain.  A defect in the afferent pathway does not necessarily have to be in the optic nerve, it could be in the retina or in the chiasm. The response of the pupils to light is produced when the brain receives the message and Cranial Nerve III (Oculomotor Nerve) causes both pupils to constrict if the pathway is intact.  Both pupils will constrict, even if only one eye is receiving the light information. AFFERENT PATHWAY PUPILLARY LIGHT REFLEX (PARASYMPATHETICCONSTRICTION) This is a four-neuron arc:  1st neuron arc: connect the retina (retina ganglion cells) to the pretectal nucleus in the midbrain at the level of the superior colliculus.  2nd neuron arc: connects each pretectal nucleus to both Edinger-Westphal nuclei (EWN), therefore a unilateral light stimulus evokes a bilateral pupil constriction.  3rd neuron arc: connect the EWN to the ciliary ganglion.  The EWN gives rise to preganglionic parasympathetic fibers that exit the midbrain with CNIII and synapse with the postganglionic parasympathetic fibers of the ciliary ganglion.  4th neuron arc: leaves the ciliary ganglion and innervates the sphincter muscle. OCULOSYMPATHETIC PUPILLARY PATHWAY (SYMPATHETIC-DILATION) This is a three-neuron arc.  1st neuron (Central): starts in the posterior hypothalamus and ends in the ciliospinal center of Budge (in C8-T2).  2nd neuron (Preganglionic): leaves the ciliospinal center of Budge and travels over the apical pleura of the lung and into the superior cervical ganglion (SCG) at the level of the carotid bifurcation.  3rd neuron (Postganglionic): joins the ophthalmic division of the trigeminal nerve (CN V) to reach the ciliary body and the pupil dilator muscle via the nasociliary and long ciliary nerves. Interruption of the sympathetic pathway at any level, will produce Horner’s Syndrome. 1 3 2 3rd Sympathetic 2nd 1st NEAR REFLEX AND ACCOMMODATION PATHWAY When an object at near is fixated both eyes:  Converge, the intraocular lens accommodates and both pupils constrict.  This is known as the near response  Even thought they are associated movements, they are not dependent on one another. Pupillary constriction for both parasympathetic pathway and near reflex have a final common efferent pathway from the EWN to the iris sphincter.  They differ in the origin of the supranuclear input They also have slightly different pathways in the midbrain: Near reflex passing ventrally in the EWN Light reflex passing dorsally in the EWN PUPIL TESTING It is important to always test pupils, since most patients are unaware of any pupillary abnormality.  Spouse, friend or physician may notice the abnormality. Used to assess afferent and efferent neurological pathways responsible for pupillary function. Examiner will always test: Direct, Consensual, Near/Accommodative and Afferent pupillary reaction as well as pupil size, shape and integrity. PUPILS TESTING Equipment:  PD ruler in mm  Penlight or transilluminator  Distance and near target Set Up:  Patient without correction  Dim illumination, enough for pupils to be seen  Examiner stands at 25cm from patient, off to one side, not obstructing visual axis. PUPIL TESTING: MEASURING PUPILS 1. Evaluate roundness of each pupil  Pupils should be round 2. Measure the size of each pupil (OD and OS) in mm  Measure pupils in dim illumination  Measure pupils in bright illumination This is used to rule out efferent defects by examining for anisocoria. Measure as well the palpebral aperture  Important if ptosis is suspected PALPEBRAL APERTURE PUPIL EVALUATION Direct Response:  Shine OD only  Observe size and speed of reaction in OD.  Repeat twice, then shine OS only. Consensual Response:  Shine OD only.  Observe size and speed of rection in OS.  Repeat twice, then perform while shining OS. NEAR/ACCOMMODATIVE RESPONSE Near reflex: only needs to be tested if the light responses are abnormal or sluggish. A distance target (20/400) and a near target (at 10-40cm from the patient) Ask the patient to fixate the near target, then at the distance target. Observe for accommodative or near response constriction of the pupil while fixating the near target and dilation when observing the distance target.  Repeat several times Compare magnitude and briskness of near response to magnitude and briskness of the light response. NEAR/ACCOMMODATIVE REFLEX RECORDING Speed of pupil reaction:  Brisk: 4 to 3  Sluggish: 2 to 1  None: 0 Accommodation:  Brisk  Sluggish  None AFFERENT PUPILLARY PATHWAY TESTING Swinging flashlight test or Marcus Gunn (MG) test Distance target Dim room illumination. Shine transilluminator at visual axis. Move light rapidly between the eyes, leaving the light 3 seconds on each eye. Observe for response (dilation and constriction) Important to have equal light intensity and rhythm https://www.youtube.com/watch?v=HSYo7LhfV3A AFFERENT PUPILLARY DEFECT (APD) Swinging flashlight test or Marcus Gunn test (MG) A positive relative afferent pupillary will present when there is asymmetry of the afferent light transmission. Normal intact afferent fibers:  Both pupils will constrict equally and re-dilate slightly when either eye is stimulated. AFFERENT PUPILLARY DEFECT (APD) With (+) APD, the affected eye perceives light dimmer.  The affected eye constricts less in direct and re-dilates more than normal or than the fellow eye.  The affected eye has a greater consensual response coming from the normal eye than direct.  Affected pupil: its consensual reaction > direct reaction  Normal pupil: its direct reaction > consensual reaction. MOST COMMON ERRORS IN APD TESTING 1. Too slow a swing in the swinging flashlight test 2. Using too low light level 3. Blocking the patient’s view of target  This leads to accommodation and subsequent pupil constriction 4. Forgetting to check pupil reflexes prior to instilling mydriatics/cycloplegics PUPIL HICCUP Hiccup: rhythmic fluctuations in pupillary size when there is a steady illumination, because of unbalance between the sympathetic and parasympathetic innervation.  Normal phenomenon May sometimes be observed during a CN III Palsy Recovery This is not an APD https://youtu.be/sUNpE_Q8Cz8?si=u6n8QrP2P80enYp3 MEASURING AN RAPD: +1 RAPD (mild): initial constriction, early re-dilation +2 RAPD (moderate): no initial movement of the pupil, then dilation. +3 RAPD (severe): immediate dilation. +4 RAPD: amaurotic pupil Can be also measure using Neutral Density Filters (NDF) over the normal eye, until both eyes have equal pupil constriction. https://www.youtube.com/watch?v=XuSHunkGWYs REVERSE/INVERSE APD TESTING A patient that has a pupil that is distorted or unreactive (trauma or surgery) and the opposite eye has a condition that affects the afferent pathway (ex: optic neuritis). When testing:  Perform the Swinging flashlight test, while observing the functioning pupil.  Observe for constriction when both eyes are shined. Richmond Eye Associates, Relative Afferent Pupillary Defect How to examine RAPD - YouTube AION Optic Atrophy CAUSES FOR APD Lesions anterior to the chiasm: CRAO  Optic nerve:        Optic neuritis Retrobulbar Neuritis Optic atrophy Anterior Ischemic Optic Neuropathy (AION) Asymmetric Primary Open Angle Glaucoma (POAG) Optic Nerve Trauma Chiasm Compression by mass  Retina  Marked retinal detachment  Extensive Retinal Pathology  Major Retinal Vascular Occlusions  Central Retinal Artery Occlusion (CRAO)  Central Retinal Vein Occlusion (CRVO) CRVO PUPILLARY RECORDING PERRLA (-) APD OD/OS  Pupils are Equally Round and Reactive to Light and Accommodation, No Afferent Pupillary Defect in OD and OS (+) RAPD or (+) MG  Relative Afferent Pupillary Defect (RAPD)  Marcus Gunn  Always need to specify the affected eye Record abnormalities  OD is round, reactive to light. OS is distorted by surgery and sluggish in direct (D) and consensual (C).  OD RRL (-) APD; OS Irregular, sluggish D and C PUPILLARY RECORDING APD can be quantified by using NDF  Record log units where pupillary constriction was the same for both eyes.  Ex: + RAPD OS, 0.3 log ND filter PERRLA, (-) APD OD/OS, OD brisk OS brisk PERRL (-) APD OD/OS OD +4 OS +2 (sluggish) PRRL, (-) APD OD/OS, OD>OS 1 mm in dim and bright OD RRL (-) APD, OS irregular, sluggish D (direct) and C (consensual) KEY POINTS Pupils sizes (OD/OS) should be equal in both eyes at both dim and bright illumination  If in doubt, ask the patient for photos and evaluate them carefully If pupil sizes are unequal:     Is the direct/consensual response equally strong in both eyes? If the pupil size difference larger in dim or in bright illumination? Is the near/accommodative reflex the same for both eyes? Amplitude of accommodation equal in both eyes? KEY POINTS If the afferent arc is intact, the direct response should be equal to the consensual response  Always evaluate both direct and consensual response For direct and consensual evaluation the light source should not be shined directly into the patients eye, it should be directed from slightly inferior  Avoid bleaching the retina VIDEOS Parasympathetic Pathways: Pupillary Light Reflex (tedmontgomery.com) Cranial Nerves II & III - Pupillary Light Reflex 5/25 – YouTube Ophthalmology - Relative Afferent Pupillary Defect (RAPD) - YouTube ANISOCORIA If there is anisocoria present:  Does it vary in different illuminations?  Is the difference more significative in dim illumination?  If the difference more significative in bright illumination? ANISOCORIA Anisocoria that is equal in dim and bright, without ptosis: Physiological anisocoria Anisocoria more pronounced in dim illumination, with mild ptosis in the ipsilateral side of the miotic pupil: Horner’s Syndrome (Oculosympathetic Syndrome) Anisocoria more pronounced in bright illumination: characteristic of parasympathetic dysfunction. KEY POINTS Light-near dissociation, refers to conditions where the light reflex is absent or abnormal, but the near response is intact  There is no clinical condition in which the light reflex is present, and the near response is absent For bilateral optic nerve disease, no RAPD will be seen, unless disease is asymmetric ABNORMAL PUPIL FINDINGS CONDITIONS TO DISCUSS Pharmacological Mydriasis Amaurotic Pupil-afferent Argyll Robertson’s Pupil Adie's Tonic Pupil Horner’s Syndrome Oculomotor Palsy PHARMACOLOGICAL MYDRIASIS AND MIOSIS Sympathomimetics can cause 1-2mm of dilation, stimulating the dilator muscle.     Phenylephrine: Preparation H Naphazoline: Naphcon-A, Clear Eyes Cocaine, Crack Jimsonweed PHARMACOLOGICAL MYDRIASIS AND MIOSIS Parasympatholitics: can cause mydriasis of up to 8mm, inhibits the sphincter muscle  Tropicamide, Atropine, Scopolamine (Dramamine), Plants (deadly nightshade or belladonna) Miotics:  Pilocarpine, pesticides, flea powder  Narcotics and opioids cause pinpoint pupils  Heroin  Codeine  Morphine PHARMACOLOGIC MYDRIASIS Usually tend to be by accident  Phenylephrine, Naphazoline, Tropicamide, Atropine Patient will have poor or no light or near response  Very important to differentiate from aneurysm affecting CN III Diagnosis  Pilocarpine 1% instillation  Pharmacologic mydriasis: will NOT constrict  Non-pharmacologic mydriasis: will constrict  Important to rule out aneurysm AMAUROTIC PUPIL This is caused by an afferent defect, essentially this is a “blind eye”  Grade 4 APD  No light perception (NLP) as a result of an optic nerve lesion Pupils will have no light reaction in direct evaluation  Positive consensual evaluation reaction (fellow eye is stimulated) The fellow eye will have no consensual reaction (when affected eye is stimulated) Near reflex will be present for both eyes (-) D, (+) C, other eye (+) D and (-) C, (+) Near OU ARGYLL ROBERTSON PUPIL Light-near dissociation  Sluggish or no reaction to light but brisk response to near stimuli Pupils tend to be small and irregular in shape (12mm)  Poor dilation in darkness Bilateral and symmetrical presentation Poor dilation after instillation of mydriatics Hallmark of neurosyphilis (tertiary syphilis)  But may occur with diabetes mellitus, chronic alcoholism, MS, CNS degenerative disease, midbrain tumors. ARGYLL ROBERTSON PUPIL Cause:  Site of lesion is the region of the sylvian aqueduct in the rostral midbrain.  In this location the damage interferes with the light reflex fibers but it spares the fibers subserving pupillary constriction for near viewing. https://www.youtube.com/watch?v=IbBYxGk1pUw ADIE’S TONIC PUPIL Unilateral or bilateral tonically reacting pupils developing in otherwise healthy patients  80% unilateral Pupil appears abnormally dilated with sluggish reaction to light but better reaction to near stimuli, but still sluggish  Impaired parasympathetic ciliary ganglion, though to be caused by denervation of the postganglionic nerve supply to the sphincter and ciliary muscle  This leads to pupillary and accommodative changes After fixating the near stimuli, there is slow re-dilation of the affected pupil ADIE’S TONIC PUPIL Slit lamp examination of the pupil often revealed sectoral palsy with vermiform movements of the margin. https://www.youtube.com/watch?v=50qUET6te0s ADIE’S TONIC PUPIL Mostly idiopathic, benign condition More commonly seen in between 20 to 50 years of age 70% of the cases are in females May be accompanied by hyporeflexia or areflexia  Reduction in reflexes Accommodative response, may be initially affected, but tends to improve with time  Tonicity to light response tends to gets worse There is no treatment, reassurance is key ADIE’S TONIC PUPIL Diagnostic Tests:  Dilute one part Pilocarpine 1% with 8 parts of saline solution to achieve Pilocarpine 0.125%  Instill 1gtt of Pilocarpine 0.125% OU and wait 30 min. Adie’s Tonic Pupil will constrict, normal pupils will not be affected by such a low concentration  This is due to denervation and hypersensitivity HORNER’S SYNDROME If sympathetic innervation to the eye is interrupted this results in:  Retractor muscles in the eyelids are weakened: ptosis  Dilator muscle of the iris is weakened: miosis  Vasomotor and sudomotor control of parts of the face are lost: anhidrosis A lesion of the ocular sympathetic fibers will produce Horner’s Syndrome.  Anisocoria is more apparent in dark, and may even disappear in bright conditions.  Triad: Ptosis, miosis and anhidrosis  Ipsilateral HORNER’S SYNDROME Lesions can be located anywhere along the sympathetic pathway Differential diagnosis between:  Central Lesions (1st order)  Preganglionic Lesions (2nd order)  Postganglionic Lesions (3rd Order) How to Examine Horner's Syndrome YouTube HORNER’S SYNDROME Anisocoria more pronounced in dark than in bright Pupillary light and near responses are unimpaired Triad:  Miosis  Ptosis: due to primary paralysis of the superior tarsal (Muller’s) muscles  Sometimes the lower lid is slightly elevated due to loosing nerve supply as well, this will produce an upside down ptosis (lower lid is slightly elevated)  This will produce a narrowing of the palpebral fissure, apparent enophthalmos  Anhidrosis: due to vasomotor and sudomotor changes, ipsilateral to the affected eye  Will only occur in central and preganglionic Horner’s Syndrome, not in postganglionic HORNER’S SYNDROME May be congenital or acquired  If congenital, iris depigmentation (heterochromia) may be present in the affected eye  If acquired may be due:  Trauma  Malignancy HORNER’S SYNDROME Central Neuron (1st Order):  Often accompanied by other hypothalamic, medullary or brainstem abnormalities.  Examples: vascular occlusion, intraparenchymal neoplasms, cervical spondylosis. Preganglionic (2nd Order):  Malignancy are the most common cause, especially lung (Pancoast Tumor) and breast tumors.  Accidental or surgical injury  Disc herniation at C8 or T1, trauma, pneumothorax, coronary artery bypass, pacemaker insertion. Postganglionic (3rd Order):  Lesions may be extracranial or intracranial  Tumors, inflammatory lesions and other masses in the neck, carotid dissections, aneurysms, infections and other lesions of the cavernous sinus, Cluster headaches, giant cell arteritis, skull base neoplasms or fractures. HORNER’S SYNDROME Pharmacologic diagnostic testing is performed since it is important to differentiate between physiologic anisocoria. Cocaine test is most commonly used:  Blocks reuptake of norepinephrine at the neuroeffector junction  Normal eyes Cocaine 4-10% causes dilation  In Horner’s Syndrome no norepinephrine is released (due to lesion) and cocaine will not dilate the pupil Cocaine 4-10% is very difficult to obtain clinically and it is not diagnostic of lesion location  Apraclonidine can be used to verify Horner’s diagnosis HORNER’S SYNDROME Apraclonidine 0.5-1% is an alpha adrenergic agonist     In normal eyes dilation effect is very minimal Acts on the delayed sensitivity of alpha 1 receptors in the dilator muscle Will produce dilation of the Horner’s Syndrome pupil, due to hypersensitivity Normal eye will not dilate, Horner’s pupil will dilate HORNER’S SYNDROME Lesion localization:  Hydroxyamphetamine 1% is clinically useful in differentiating between central and preganglionic lesions and postganglionic lesions.  No diagnostic test for central vs. preganglionic  Hydroxyamphetamine releases norepinephrine from the stores in the adrenergic nerve ending, producing significant mydriasis in normal subjects.  If Cocaine or Apraclonidine test has been performed, Hydroxyamphetamine cannot be performed until 2448 hours after.  Only performed when Horner’s Syndrome has been diagnosed.  If the lesion is central or preganglionic: will produce normal mydriasis.  If the lesion is postganglionic: will not produce mydriasis. ISOLATED III CN PALSY Sudden onset of unilateral ptosis with eye or head pain. Eye is exotropic and hypotropic (down and out)  Complaints of diplopia With and without pupil involvement ISOLATED III CN PALSY Depending on where the lesion is located the pupillary fibers might or might not be affected. ISOLATED III CN PALSY WITH PUPIL INVOLVEMENT Most common cause: Posterior communicating artery aneurysm Other causes:       Tumors Trauma Leukemia Uncal Herniation Pituitary apoplexy Ischemic vascular disease (rare with pupil involvement) Patients need to be referred for neurologic evaluation STAT. ISOLATED III CN PALSY W/O PUPIL INVOLVEMENT Tend to be ischemic in nature, but this is not always the case. Follow patient closely, they might develop pupil involvement soon after initial presentation.  Vascular disease: can cause an infarct of IIICN central fibers (pupil sparing) Causes:  Ischemic micro vascular disease (diabetes, hypertension)  Cavernous sinus syndrome  Giant Cell Arteritis (GCA) ISOLATED III CN PALSY MANAGEMENT If pupil involvement is present: referred for neuro consult in nearest ER STAT.  Must rule out PCA aneurysm  MRI/MRA recommendation If pupil sparing, patient has diabetes or hypertension, follow the patient closely and monitor for possible pupillary involvement.  Refer to PCO for medical/lab work-up  F/U in 5-7 days  Most ischemic causes resolve in 90 days, if not resolved, order neuro testing. If pupillary sparing in younger than 50 y/o order neuro testing unless known vascular condition. In children less than 10 y/o regardless of pupils order neuro testing. PUPIL SUMMARY Dilation lag, Cocaine test, Ptosis Physiologic Anisocoria Horner’s Syndrome Greater In Dark CN 3 Palsy Anisocoria Adie’s Tonic Pupil Greater in Light Slit Lamp, Pilocarpine 0.125% Pharmacologic Pupil Iris Damage DIFFERENTIAL DIAGNOSIS MORE ANISOCORIA IN DARK MORE ANISOCORIA IN LIGHT Simple physiologic anisocoria Inhibition of the sympathetic pathway Horner’s Syndrome Pharmacologic Stimulation of Sympathetic pathway Pharmacologic Pilocarpine Damage to the parasympathetic outflow to sphincter muscle Oculomotor nerve palsy Adie’s Tonic Pupil Trauma to iris sphincter Pharmacological inhibition of parasympathetic pathway Atropine, Scopolamine