PUPIL AND PUPIL AND ACCOMODATION ACCOMODATION ABNORMALITIESABNORMALITIES

Sympathetic pathway of Sympathetic pathway of pupillarypupillary innervationinnervation

PupillaryPupillary light reflexeslight reflexes

••PupilPupil diameterdiameter isis subjectsubject toto continuouscontinuous variationsvariationsasas a a functionfunction of of changeschanges in in luminanceluminance, , fixationfixation and and

psychosensitivepsychosensitive stimulistimuli..

••PupilsPupils mustmust bebe studiedstudied byby evaluatingevaluating theirtheir sizesize, , shapeshape, , symmetrysymmetry and and activityactivity ((dilationdilation and and

constrictionconstriction). ). ••ToTo evaluateevaluate sizesize and and symmetrysymmetry of of pupilspupils, ,

patientspatients are are invitedinvited toto fixatefixate a a farawayfaraway objectobject, , whichwhich mustmust notnot bebe a a sourcesource of of excessiveexcessive light light

stimulationstimulation. .

••SubsequentlySubsequently, , byby illuminatingilluminating the the patientspatients’’face face fromfrom belowbelow withwith a a weakweak light light sourcesource, ,

bothboth pupilspupils are are simultaneouslysimultaneously observedobserved and and theirtheir diametersdiameters are are determineddetermined (mm). (mm).

••In the In the normalnormal populationpopulation, , pupilpupildiameterdiameter tendstends toto bebe smallersmaller in in childrenchildren, , in the in the elderlyelderly and in and in subjectssubjects withwith dark dark

iris. iris.

••In In generalgeneral, , anisocoriaanisocoria whichwhich changeschanges withwith changeschanges of of luminanceluminanceconditionsconditions mustmust bebe consideredconsidered pathologicpathologic, , whilewhile

••anisocoriaanisocoria whichwhich remainsremains constantconstant, , indipendentlyindipendently fromfrom the the degreedegreeof of luminanceluminance and and isis associatedassociated toto a a symmetricalsymmetrical photomotorphotomotor reflex, reflex, isisthe the expressionexpression of of physiologicphysiologic or or essentialessential anisocoriaanisocoria..

••The The photomotorphotomotor reflex reflex mustmust bebe evaluatedevaluated::

••the patient the patient fixatesfixates a faraway object, a faraway object, toto inhibitinhibit the the nearnear reflex, and reflex, and eacheach pupilpupil isis stimulatedstimulated byby usingusing a high a high intensityintensity light. light.

••In the In the presencepresence of a of a pupilpupil whichwhich scarcelyscarcely reactsreacts toto the direct light the direct light stimulusstimulus, the , the indirectindirect or or consensualconsensual reflex reflex mustmust bebe examinedexamined, , bybystimulatingstimulating the the contralateralcontralateral eyeeye. .

••IfIf the reflex the reflex arcarc isis intactintact, the direct reflex , the direct reflex mustmust bebe equalequal totothe the consensualconsensual reflex (due reflex (due toto the the doubledouble decussationdecussation of the of the pupillarypupillary fibersfibers). ). ••The The amplitudeamplitude, , latencylatency and and speedspeed of of pupilpupil constrictionconstrictionafter a light after a light stimulusstimulus are are generallygenerally correlatedcorrelated toto the visual the visual acuityacuity of the of the patientpatient, , exceptexcept in in casescases in in whichwhich the visual the visual defectdefect isis secondarysecondary toto a a circumscribedcircumscribed fovealfoveal lesionlesion or a or a bilateralbilateral occipitaloccipital pathologypathology, in , in whichwhich pupilpupil activityactivity isisnormalnormal..

The The nearnear pupilpupil reflex reflex isis analysedanalysed byby askingasking the the patientpatient totofixatefixate a a farawayfaraway objectobject and and thenthen toto fixatefixate a a nearnear objectobject

positionedpositioned in front of the in front of the nosenose..

••NormalNormal visual visual functionfunction isis notnot a a necessarynecessaryrequirementrequirement toto elicitelicit the the nearnear reflex. reflex. ••The The nearnear pupilpupil reflex reflex mustmust bebe onlyonly evaluatedevaluatedin the in the presencepresence of of anan abnormalabnormal photomotorphotomotorreflex. reflex. ••The The dissociationdissociation of of photomotorphotomotor and and nearnearreflexesreflexes indicatesindicates the the presencepresence of a of a mesencephalicmesencephalic pathologypathology ((ParinaudParinaud’’s s syndromesyndrome, , ArgyllArgyll--RobertsonRobertson’’s s pupilpupil)) or the or the involvementinvolvement of of postganglionicpostganglionicparasympatheticparasympathetic fibersfibers ((AdieAdie’’s s tonictonic pupilpupil).).

••The The doubledouble hemidecussationhemidecussation of of pupillarypupillary fibersfibers at at the the levellevel of the of the opticoptic chiasmchiasm and and mesencephalusmesencephalusguaranteesguarantees the the presencepresence and and symmetrysymmetry of the direct of the direct and and indirectindirect reflex. reflex. ••EvenEven whenwhen the the afferenceafference of of anan eyeeye isis completelycompletelydeficientdeficient, the , the symmetrysymmetry of of pupilpupil diametersdiameters isismaintainedmaintained byby the the stimulistimuli originatingoriginating in the in the contralateralcontralateral eyeeye and and fibersfibers decussatingdecussating in the in the brainstembrainstem. . ••ForFor thisthis reasonreason, in , in casescases of of monolateralmonolateral blindnessblindnessanisocoriaanisocoria isis nevernever presentpresent. .

PupillaryPupillary light reflex: near dissociation light reflex: near dissociation in in Parinaud'sParinaud's syndromesyndrome

••In the In the presencepresence of of anisocoriaanisocoria ananophthalmologicophthalmologic examinationexamination isis fundamentalfundamental, , withwith particularparticular attentionattention toto the the biomicroscopicbiomicroscopicexaminationexamination of the of the anterioranterior segmentsegment and the and the measurementmeasurement of of intraocularintraocular pressurepressure. . ••ItIt isis alsoalso necessarynecessary toto excludeexclude the the presencepresenceof of ocularocular motilitymotility defectsdefects, , alterationsalterations of of eyelideyelidposition and position and activityactivity, and , and trigeminaltrigeminaldysfunctionsdysfunctions ((includingincluding cornealcorneal reflex).reflex).

••The The presencepresence of a relative of a relative afferentafferent pupillarypupillary reflex reflex (RAPD) (RAPD) isis one of the one of the mostmost importantimportant signssigns in in neurophthalmologyneurophthalmology asas itit providesprovides objectiveobjective evidenceevidence of of damagedamage toto the the anterioranterior visual visual pathwayspathways. . ••ThisThis signsign isis evidentevident in the in the presencepresence of of anan asymmetryasymmetry in in the the functionfunction of the of the afferentafferent system of the system of the twotwo eyeseyes. . ••IndeedIndeed, , whenwhen light light isis positionedpositioned infrontinfront of the of the healthyhealthyeyeeye, , bothboth pupilspupils constrictconstrict and and thenthen slowlyslowly dilatedilate; ; whenwhen the the light light isis positionedpositioned infrontinfront of the of the affectedaffected eyeeye, the , the constrictionconstriction isis reducedreduced or or absentabsent, , butbut the the subsequentsubsequentdilationdilation isis immediatelyimmediately evidentevident..

••ToTo correctlycorrectly search search forfor the the presencepresence of a of a RAPDRAPD itit isis necessarynecessary totobeginbegin withwith bothboth pupilspupils in the dark. in the dark. EachEach pupilpupil isis thenthen rapidlyrapidlyilluminatedilluminated in in anan alternatingalternating way (way (forfor maximummaximum 3 3 secondsseconds) ) passingpassingaboveabove the the nosenose. .

••A A monolateralmonolateral lesionlesion of the of the opticoptic nervenerve isis practicallypractically alwaysalwaysassociatedassociated toto a relative a relative afferentafferent defectdefect, , whilewhile a a bilateralbilateral lesionlesion onlyonlywhenwhen stronglystrongly asymmetricalasymmetrical

••HoweverHowever, a , a retinalretinal pathologypathology ((egeg. . LargeLarge retinalretinal detachmentdetachment)) maymayalsoalso determinedetermine the the presencepresence of a RAPD. A of a RAPD. A slightslight RAPD RAPD maymay bebepresentpresent in in some some largelarge macular macular lesionslesions and in and in casescases of of amblyopiaamblyopia..

••ItIt isis generallygenerally notnot presentpresent in acute in acute papilloedemapapilloedema, severe , severe refractiverefractivedefectsdefects, , cataractcataract, , nonnon--organicorganic visual visual lossloss, or , or corticalcortical lesionslesions..

Relative afferent Relative afferent pupillarypupillary defect (RAPD)defect (RAPD)

Relative afferent Relative afferent pupillarypupillary defect (RAPD)defect (RAPD)

••PHYSIOLOGIC ANISOCORIA :PHYSIOLOGIC ANISOCORIA :••The The mostmost frequentfrequent cause of relative cause of relative differencedifference in in pupilpupildiameterdiameter. . ••ApproxApprox. 20% of the . 20% of the generalgeneral populationpopulation presentspresents some some degreedegree of of anisocoriaanisocoria••PhysiologicPhysiologic or or essentialessential anisocoriaanisocoria isis generallygenerally 0,5 mm, 0,5 mm, alwaysalways lessless thanthan 1 mm. 1 mm. ••The The prevalenceprevalence of of anisocoriaanisocoria increasesincreases withwith ageage, , reachingreaching33% in the 33% in the populationpopulation over 60 over 60 yearsyears of of ageage. . ••The The differencedifference in in pupilpupil diameterdiameter in in physiologicphysiologic anisocoriaanisocoriaisis constantconstant in in differentdifferent conditionsconditions of of luminanceluminance, , withwith a a slightslight tendencytendency toto bebe more more evidentevident in in darknessdarkness. .

LESIONS of the MESENCEPHALUSLESIONS of the MESENCEPHALUS••EfferentEfferent pupillarypupillary defectsdefects associatedassociated toto lesionslesions involvinginvolving the the oculomotoroculomotornucleusnucleus and and itsits bundlebundle in in itsits mesencephalicmesencephalic pathwaypathway••FeaturesFeatures: : anisocoriaanisocoria ((associatedassociated toto defectsdefects of of motilitymotility and and ptosisptosis), and the ), and the pupilpupil withwith greatergreater diameterdiameter reactsreacts weaklyweakly toto light and light and convergenceconvergence. .

••ArgyllArgyll RobertsonRobertson’’s s pupilpupil::••neurosyphilis neurosyphilis ••smallsmall--sized (<2 mm) and sized (<2 mm) and oftenoften irregularirregular pupilspupils. . ••NearNear dissociationdissociation isis presentpresent, and , and pupilspupils show show scarcescarce dilationdilation after after instillationinstillation of of mydriaticmydriatic eyedropseyedrops. . ••SimilarSimilar featuresfeatures, , forfor the the presencepresence of of nearnear dissociationdissociation, are , are presentpresent in in diabetesdiabetes ((probablyprobably due due toto a a peripheralperipheral autonomicautonomic neuropathyneuropathy), ), chronicchronicalcoholismalcoholism, , encephalitisencephalitis and some degenerative and some degenerative diseasesdiseases. .

ParinaudParinaud’’s s syndromesyndrome,, or or dorsaldorsal mesencephalusmesencephalus syndromesyndrome••PupilsPupils in medium in medium mydriasismydriasis (4(4--5 5 mm), round and regular. mm), round and regular. ••DissociationDissociation betweenbetween light reflex, light reflex, whichwhich isis scarcescarce or or absentabsent, and , and nearnear reflex, reflex, whichwhich isis normalnormal. . ••A A consequenceconsequence of:of:Involvement of Involvement of afferentafferent pupillarypupillary fibersfibers at the at the pretectalpretectal levellevel, , thatthat isis the the fibersfiberswhichwhich, once , once leavingleaving the visual the visual pathwayspathways, direct , direct towardstowards the the pretectalpretectal nuclei. nuclei.

AssociatedAssociated toto: : ••paralysisparalysis of the of the upwardsupwards gazegaze, , ••nystagmus nystagmus (convergence(convergence--retraction) retraction) ••eyelid retraction (Colliereyelid retraction (Collier’’s s signsign). ). The The mostmost frequentfrequent causescauses of of ParinaudParinaud’’s s syndromesyndrome are: are: ••tumorstumors of the of the pinealpineal glandgland regionregion, , ••Multiple Multiple sclerosissclerosis, , ischaemicischaemic lesionslesions and and hydrocephalushydrocephalus withwith ventricularventricular dilationdilation..

PupillaryPupillary light reflex: near dissociation light reflex: near dissociation in in Parinaud'sParinaud's syndromesyndrome

Collier's signCollier's sign

LESIONS OF THE PARASYMPATHETIC SYSTEMLESIONS OF THE PARASYMPATHETIC SYSTEM••The The paralysisparalysis of the 3rd CN of the 3rd CN determinesdetermines pupilpupil involvementinvolvement generallygenerallyassociatedassociated toto ptosisptosis and and paralysisparalysis of of extraocularextraocular musclesmuscles. .

••The The involvedinvolved pupilpupil isis dilateddilated, and , and anisocoriaanisocoria isis greatestgreatest in in conditionsconditions of of high high luminanceluminance. .

••The The mydriaticmydriatic pupilpupil doesdoes notnot reactreact after after instillationinstillation of of lowlow concentrationsconcentrationsof of cholinergiccholinergic substancessubstances ((pilocarpinepilocarpine diluteddiluted toto 0,125%), 0,125%), whilewhile ititconstrictsconstricts after after normalnormal potencypotency mioticmiotic drugsdrugs suchsuch asas 1% 1% pilocarpinepilocarpine..

PupilPupil dilationdilation maymay bebe the the onlyonly signsign of of oculomotoroculomotor nervenerve paralysisparalysis in in twotwoextremelyextremely rare rare clinicalclinical conditionsconditions: : ••UncusUncus herniationherniation••basalbasal meningitismeningitis ((tubercolosistubercolosis, , sarcoidosissarcoidosis, , syphilissyphilis, , cryptococcosiscryptococcosis). ).

••The The presencepresence of of pupilpupil involvementinvolvement and and incomplete incomplete paralysisparalysis of the of the oculomotoroculomotor nervesnerves in in subjectssubjects withwith lessless thanthan 50 50 yearsyears of of ageage mustmust leadleadtoto hypothesizehypothesize the the presencepresence of of anan aneurismaneurism in the in the junctionjunction betweenbetween internalinternal carotidcarotid arteryartery and and posteriorposterior communicatingcommunicating arteryartery. (MRI and, . (MRI and, ififnegative, complete negative, complete brainbrain angiographyangiography). ).

••In In aberrantaberrant regenerationsregenerations of the 3rd CN, of the 3rd CN, especiallyespecially ifif postpost--traumatictraumatic, a , a paradoxalparadoxalinnervationinnervation of the of the pupilpupil sphynctersphyncter maymay bebeobservedobserved, , withwith sectorialsectorial contractioncontraction duringduringabductionabduction. .

••The The presencepresence of of mydriasismydriasis maymay bebe of of traumatictraumatic originorigin. . ••A A contusivecontusive trauma trauma maymay in in factfact damagedamage the the sphynctersphyncter musclemuscle, , and in and in thesethese casescases, the , the presencepresence of of lacerationslacerations of the of the pupilpupil edgeedgeand and defectsdefects of of transilluminationtransillumination of the iris of the iris maymay bebe observedobserved. . ImmediatelyImmediately after trauma, the after trauma, the pupilpupil maymay bebe mioticmiotic, , butbut changeschanges totomedium medium mydriasismydriasis earlyearly on, on, demonstratingdemonstrating a a weakweak reactionreaction totolight. light.

••The The monolateralmonolateral instillationinstillation, , accidentalaccidental or or volontaryvolontary, of , of mydriaticmydriaticdrugsdrugs ((suchsuch asas atropinatropin) ) maymay bebe the cause of the cause of anisocoriaanisocoria((pharmacologicalpharmacological anisocoriaanisocoria). In ). In thesethese casescases the the dilateddilated pupilpupilweaklyweakly reactsreacts toto light and light and toto the the nearnear reflex. reflex.

AdieAdie’’s s tonictonic pupilpupil

••PathologyPathology withwith unknownunknown etiologyetiology, , whichwhichdeterminesdetermines pupilpupil alterationsalterations probablyprobably secondarysecondary toto

damagedamage at the at the levellevel of of postganglionpostganglion fibersfibers. . ••AsAs the the fibersfibers innervatinginnervating bothboth the the pupillarypupillarysphynctersphyncter musclemuscle and the and the ciliaryciliary musclemuscle are are

involvedinvolved, , bothboth pupilpupil reflexesreflexes and and accomodationaccomodation are are compromisedcompromised. .

••The The pathologypathology isis characterizedcharacterized byby anan irregularirregular and and dilateddilated pupilpupil, , withwith scarcescarce or or absentabsent reactionreaction toto light. light.

OftenOften associatedassociated toto hypohypo--areflexiaareflexia. .

Adie's pupilAdie's pupil

LESIONS OF THE SYMPATHETIC LESIONS OF THE SYMPATHETIC SYSTEMSYSTEM

HornerHorner’’s s syndromesyndrome::Interruption of the Interruption of the ocularocular

sympatheticsympathetic system system duringduring itsitspathwaypathway..

CharacterizedCharacterized byby: : miosismiosis, , slightslightptosisptosis, , …… enophthalmusenophthalmus

Acquired Acquired Horner's Horner's

syndromesyndrome

Congenital Horner's syndromeCongenital Horner's syndrome