Explanationofterms
[pupiloftheeye]Acontractibleholeintheirisoftheeye.Inmostvertebrates,itisroundwhenenlargedorreduced,butthefoxWhenthecat’spupilscontract,theybecomeelliptical,likeaseam.
Pupilposition
Theanteriorpartofthevascularmembraneoftheeyeball,thatis,thecenterofthescleraandthecircularhole.Thesmoothmusclearrangedinacircularshapealongthepupiliscalledthepupillarysphincter.Thesphinctershrinksthepupilwhenitcontracts.Thesmoothmusclesarrangedradiallyalongthepupilsarecalledpupildilators.Whenthedilatormusclescontract,thepupilsdilate.Becausethepupilscandilateorshrink,theycanadjusttheamountoflightenteringtheeyeball.Thepupilofanormalpersoncanreflexivelyadjustitsownsize.Whenthelightincreases,thepupilshrinks;whenthelightdecreases,thepupildilates.Ifthepupilreflexisabnormalordisappears,itindicatesthattheadjustmentfunctionofthenervoussystemisimpaired.Therefore,thepupil'slightreflectionisoftenusedclinicallytocheckthefunctionalstateofthenervoussystem.
Pupilsize
Pupillarysizevarieswithage,race,refractivestatus,lightintensity,targetdistanceandmoodchanges.Itisgenerally2to5mm,withanaverageofabout4mm.
Thepupilsofnewbornsareverysmallandstarttoexpandonly3weeksafterbirth.Youngpeoplearelargerthanmiddle-agedpeople.Peoplebetween20and50yearsoldhavepupilsof2to3mminthesun,andthenshrinkagaininoldage;Thepupilsofthehyperopiceyesaresmaller,andthepupilsofthemyopiaeyesarelarger;Caucasiansareslightlylargerthanthoseoftheyellowrace;thepupilsofbotheyesareequalorlessthan1mmapartwhenlookingforward.Thepupiloftheeyeisturnedinward;thepupilshrinkswhensleepingorinbrightlight,andthepupilislargerinthedark;thepupilshrinkswhenlookingatnearobjects,andthepupilislargerwhenlookingatdistantobjects.Thelimitsofpupildilationordilationare1.5and8mm,andthedifferencebetweentheeyesislessthan0.25mm.Thedilationandreductionofthepupilarecausedbythecontractionofthedilatorandsphincter(bothsmoothmuscle).Thedilatorisradiallylocatedattheperipheryoftheiris.Whencontracted,thepupildilates,andwhenitrelaxes,thepupilshrinks;thesphincterisatthefreeedgeoftheiris,Inaringshape,shrinksthepupilwhencontracted,anddilateswhenrelaxed.Bothareinnervatedbysympatheticandparasympatheticnerves,whichdilateorshrinkthepupils.Thepupildilatormuscleisinnervatedbythecervicalsympatheticnerve,andthesympatheticnervefibersfromthecerebralcortexenterthepupildilationcenteroutsidethesubthalamicfunnel;thegraymatterfibersthatcrossalongthecerebralaqueductpassthroughtheinnercapsuletoreachtheciliaryspinalcordcenterofthespinalcord,namelyBudge’sCentral(intheneck6andchest4),itsnervefibersenterthesuperiorcervicalsympatheticganglion,thepostganglionicfibersentertheskullthroughtheinternalcarotidartery,entertheeyenervebeforethetrigeminalganglion,andthenpassthroughthenasociliarynerveandthelongciliarynerve.Distributedinthepupildilatormuscles.ThesympatheticnerveinhibitoryfiberssentfromthehypothalamustothecentralEdinger-Westphalnucleus,sothesympatheticnervehasaninhibitoryeffectonthemioticcenter.Forexample,whenemotionalimpulse,thepupilcanbedilatedbycentralinhibition.Thepupillarysphincterisinnervatedbytheparasympatheticnerve.ThenervefibersoriginatefromtheEdinger-Westphalnucleusinsidetheoculomotornucleusofthemidbrain,andthenervefibersoftheregulatingreflexnucleus(Perlia'snucleus)entertheorbitintheoculomotornerve,fromtheinferiorobliquemuscle.Branchingout,forwardtotheciliaryganglionsendsout10-20shortciliarynervefibersintotheeyeball,anastomosingwiththelongciliarynervetothepupillarysphincterandciliarymuscle.Bothmuscleshaveanantagonisticeffect,butalsoachieveanaccuratebalanceunderthemutualinnervation.Therefore,thechangesobservedinthecliniccanmakethelocalizeddiagnosisofthediseaseoftheeyeandcranialnervoussystem.Inaddition,pupildilationandcontractionadjustthelightenteringtheeyetoensureclearvision.
PsychologicalImplications
Eckhart,aprofessorofpsychologyattheUniversityofChicago,oncedidanexperiment.Duringtheexperiment,herandomlyshowedsomephotosofmaleandfemaleparticipants,andthenobservedthechangesintheirpupils.Hefoundthatwhenwomensawpicturesofmothersholdingtheirchildren,theirpupilsexpandedbyanaverageof25%,whilemensawtheirpupilsenlargedbyanaverageof20%whentheysawnudepicturesofwomen.Theexperimentalresultsalsoshowthatthesizeofhumanpupilswillnotonlychangewiththebrightnessofthesurroundingenvironment,butalsoaffectedbythedegreeofconcernandinterestinthetarget.
Justliketheusualsaying"eyescanspeakbetterthanmouth",allhumanmentalactivitiesarerevealedintheeyes.Ifyoucarefullyobservethechangesinthepupils,youcanknowthepsychologicalstateoftheotherparty.Theotherpartylookedabsent-mindedlylistening,butthepupilsdeepinhisblackeyesweregraduallyexpanding.Fromthis,itcanbeconcludedthathisnonchalantexpressionwashidinghisintenseattentiontothetopic.
Medicalconcept
PupilreferstoirisTheopeninginthemiddleistheportalforlighttoentertheeye.
Theirisintheeyeisdisc-shapedwithasmallroundholeinthemiddle.Thisiswhatwecallthepupil,alsocalledthe"pupil."Thenormalvalueis2.5-5mm(2-5mm),whichshrinksinbrightlightandspreadsindarklight.Therearetwosmallmusclesintheiris,oneiscalledthepupillarysphincter,whichsurroundsthepupilandislessthan1mmwide.Itisresponsibleforthereductionofthepupilandisinnervatedbytheparasympatheticnerveintheoculomotornerve;theotheriscalledpupildilation.Themuscle,whichisarrangedradiallyintheiris,isresponsiblefortheopeningofthepupilandisinnervatedbysympatheticnerves.Thesetwomusclescoordinatewitheachother,restricteachother,andshrinkonebyonetoadapttovariousenvironments.
Theirisiscomposedofmultipleunitsofsmoothmuscle;aroundthepupilisthecircularmusclelayer,whichisinnervatedbytheparasympatheticnervefibersintheoculomotornerve,whichshrinksthepupilwhencontracted,soitisalsocalledthepupillarysphincter;theperipheralpartoftheirisItisadivergentmusclefiber,whichisinnervatedbysympatheticnervefibersascendingfromtheneck,anddilatesthepupilwhenitcontracts,soitisalsocalledmydriaticmuscle.Thepupillarysphincterandthepupildilatorareveryfewmusclesdifferentiatedfromtheneuroectoderminthehumanbody.
Thesizeofthepupilcancontroltheamountoflightenteringtheeye.Thediameterofordinarypeople'spupilscanvarybetween1.5-8.0mm.Assumingthatthepupildiametercanbeincreasedby5timeswhenapersonentersadarkroomfromabrightplace,thepupil'slight-receivingareashouldbeincreasedby25times;visiblepupilchangeshavetheeffectofkeepingtheamountoflightenteringtheeyerelativelyconstantunderdifferentlightingconditions.However,theintensityofthestrongsunlightinthedarkroomisactuallyreducedbyabout1milliontimes,sothechangeofpupilsizealoneisfarfromenoughtokeeptheamountoflightenteringtheeyeconstant.Infact,thehumaneyereliesondifferentphotoreceptorcellsintheretinatoreceivelightstimulationunderdifferentbrightnessconditions.Therodcellsthatworkindarklightaremoresensitivetolightthanthosethatworkinbrightlight.Theconecellsaremuchlarger,sowhenyoulookatsomethinginthedark,youonlyneedtoincreasetheamountoflightthatenterstheeye.
Thepupilisliketheapertureinacamera,whichcanshrinkorenlargewiththeintensityofthelight.Whentakingpictures,weallknowthatwhenthelightisstrong,opentheaperturealittlebit,whenthelightisdark,opentheaperturealittlebit,alwaysletenoughlightenterthecamerathroughtheaperture,andexposethefilm,butnottoostrongThelightdamagesthenegatives.Thepupilalsohasthisfunction,butitsadaptationtotheintensityoflightisdoneautomatically.Throughtheadjustmentofthepupils,therightamountoflightisalwaysmaintainedtoentertheeyes,sothattheimageofobjectsfallingontheretinaisclear,andthereisnoexcessivelighttoburntheretina.Althoughthepupilisnotarefractiveelementintheeyeballopticalsystem,itplaysanimportantroleintheeyeballopticalsystem.Thepupilcannotonlyrespondtothebrightnessanddarkness,adjustthelightenteringtheeye,butalsoaffectthefocaldepthandsphericalaberrationoftheeyeballopticalsystem.
Therangeofpupilchangescanbeverylarge.Whenitisextremelycontracted,thediameterofthehumaneyepupilcanbelessthan1mm,andwhenitisextremelyenlarged,itcanbegreaterthan9mm.Theirissphinctercanshrinkto87%ofitslength.Thisisalmostimpossibleforothersmoothmusclesorstriatedmusclesofthehumanbody.Adultpupilsaregenerally2-4mmindiameter,withaperfectroundshape,thetwosidesarethesamesize,andthedifferencebetweenthetwosidesisnomorethan0.25mm,butifthepupildiametersoftheeyesdifferby0.25-0.5mm,thereisnoabnormalityinpupilreactionanddrugexperiment,whichcanbeconsideredasphysiologicalSexpupilsvary.
Inadditiontochangingwiththeintensityoflight,thepupilsizeisalsorelatedtofactorssuchasage,refraction,andphysiologicalstatus.Pupilresponseisdividedintothefollowingtypes:responsetolight,darkresponse,accommodativesetaccompaniedbypupilresponse,andeyelidreflex.
Generallyspeaking,thepupilsoftheelderlyaresmall,whilethepupilsofyoungchildrentoadultsarelarger,especiallyduringadolescence.Thepupilsofmyopiapatientsarelargerthanthoseofhyperopiapatients.Pupilswillopenupwhenyouarenervousandexcited,andwillshrinkwhenyoutakeadeepbreath,workmentally,andsleep.Inaddition,whentherearecertaindiseases,orwhencertaindrugsareused,thepupilswillalsoopenorshrink,suchasintracranialhematoma,headinjury,encephalitis,gaspoisoning,glaucoma,etc.,oruseatropine,newforintDrugssuchasepinephrine,epinephrine,etc.canmakepupilsdilate;pontinehemorrhage,tumors,organophosphatepoisoning,iridocyclitis,etc.,orpilocarpine,morphineandotherdrugscanallmakepupilsshrink.
Thepupilisthepassageoftheanteriorandposterioraqueoushumor.Onceitisblocked,itwillobstructtheflowofaqueoushumorintheeye,resultinginincreasedintraocularpressureandsecondaryglaucoma.Therefore,thepupilopeningorshrinkinghasimportantclinicalsignificance.
Whenthepupilisexposedtolight,theaperturebecomessmaller,whichiscalleddirectlightreflection.Iftheothereyeisilluminated,thepupilofthenon-illuminatedeyewillshrink,whichiscalledindirectlightreflection.Whenlookingatnearobjects,thedilationofthepupilduetoaccommodationandconvergenceiscallednearpupilreflex,whichisthecoordinationeffectofthecerebralcortex.
InPRKandLASIK,theablationcenteredonthepupilismoresuitablethantheablationcenteredonthevisualaxis,becausethepostoperativesymptomsarealwaysrelatedtothepupildilationexceedingtheablationzoneinadarkenvironment.Ifthepatient'sKappaangleislarge,thecuttingshouldbeoffsettothevisualaxisaccordingly.
Pupildilation
Sympatheticnervesignalscancausethedilatormusclestocontract,therebydiffusingthepupils.Damagetofacialsympatheticnervescancauseunilateralpupildilation(Horner'ssyndrome).
Whenhumanbeingsseeobjectsthatarouseinterestorareexcited,theirpupilswillalsodilate.Psychologicalresearchhasfoundthatthepupilsarelargerthantheaverageface,especiallythefemalefaceisconsideredmorebeautiful.
Atropineandotherdrugscandilatethepupilsandareusedinopticstoeliminatetheeffectofpupilreflectionduringoptometry.Inaddition,drugssuchasLSDandcocainecanalsocausepupildilation.
Pupillarydilationisusedtojudgedeath.
Pupillaryreduction
Whentheeyeencountersastronglight,theirissphinctermusclecontractstocausethepupiltoshrinktoprotectthefundusoftheeye.Thisprocessisgovernedbythebrainstem.Therefore,thelossofpupilreflexisusedinmedicinetojudgedeath.
Thepupilsshrinkwhenthemoodiscalm.Inaddition,morphine,heroinandotherdrugscanalsocausepupilstoshrink.
Animalpupils
Thepupilsofcatsandfoxesareerect
Thepupilsofsheepandgoatsarehorizontallyslit
Humansandmanyanimals(Exceptforafewfishes)thesizeofthepupiliscontrolledbytheunconsciousirisexpansionandcontractiontoadjusttheintensityofthelightenteringtheeye.Thisiscalledpupilreflex.Forexample,thediameterofahumanpupilisabout1.5mminbrightlight,anditexpandstoabout8mmindimlight.
Theshapeofthepupilofananimalisdeterminedbytheopticalpropertiesofthevitreousbody,theshapeandsensitivityoftheretina,andthelivingenvironmentandneedsofthespecies.Generallyroundorslit-shaped,thepupilsofsomeaquaticanimalshavemorebizarreshapes.
Slitpupilsarecommoninanimalsthatmoveunderdifferentlightintensities.Understronglight,thesepupilsshrinkintosmallslits,butstillallowlighttofalltoalargepartoftheretina.Thedirectionoftheseammayberelatedtothedirectionofmovementthattheanimalneedstodetectwithhighsensitivity.Forexample,thepupilsofdomesticcatsareerected,whichisconvenientfordetectingthelateralmovementofpreysuchasmice.Foxesandmanysnakesalsohaveslitpupils.
Whentakingaphotowithaflash,thepupilsaretoolatetocloseintime,andtheflashilluminatestheretinawithabundantbloodvesselsinthefundusoftheeye,formingaredeyephenomenon.Thecamerawiththe"red-eyereduction"functionistopre-flashonce,sothatthepupilshavereachedacontractedstatewhentheyareofficiallyflashing.
Pupillarycolorchangesanddiseases
Normalpupilsareround,blackandtransparent,equalinsizeonbothsides,withadiameterofabout2.5mm,exceptforchangesinphysiologicalregulationInaddition,ifthepupildiameterislessthan2.0mmorgreaterthan5mm,theedgesareirregular,thecolorisabnormal,andtheresponsetolightisslowordisappears,whichoftenindicatestheoccurrenceofsomediseases.
Whitepupilsareseenincataracts,iridocyclitis,glaucoma,eyetrauma,highmyopia,orsystemicdiseasessuchasdiabetes.Ifyoufindthatyourpupilsarewhite,youshouldgototheophthalmologydepartmentandinternalmedicinedepartmentfordetailedexamination.
Blue-greenpupilsarecommoninglaucoma.Thereisacertainamountofpressureinthenormaleyeball.Whentheintraocularpressureistoohighandglaucomaoccurs,duetocornealedemaandaseriesofchangesintheeye,thepupilswillemitabluish-greenreflection,theeyeballswillbecomelikehardrubber,andtheeyeswillbeswollen.Tormented.
Pupillaryrediscommoninoculartraumaorcertainintraocularbleedingdisorders.Dependingontheamountofbleedingintheeye,thepupilscanbeindifferentshapes,andvisionisalsoimpairedindifferentdegrees.
Pupilshapeisrelatedtopredation
Whetherananimalisapredatororapredatormaydeterminetheshapeofitspupil.Aftertheresearchersanalyzedmorethan200terrestrialspeciesincludingthecanine,cat,reptilian,andhoofedfamily,scientistsfoundthatshorterambushpredators,suchasalligatorsandfoxes,haveverticalpupils.Predatorssuchasgazellesandsheepoftenhavehorizontalpupils.
Theverticalpupilisgoodforvisuallyobservingthedistancebetweenthepreyandtheprey.Itisveryusefulforpredatorswhohideintheshadowsandwaitforopportunities,butmusthitwithasingleblow.Thehorizontalpupilgivesthepredatorabroadperspective,whichissuitableforspottingthepredatorsneakingupfromallangles.Atthesametime,herbivorescankeeptheirpupilsparalleltothegroundbyrollingtheireyes,whichalsoenhancestheirabilitytoobserve.
Theroundpupilsaremostlyownedbypredatorsthattracktheirprey,suchascheetahs,orhigherambushpredators,suchaslionsandtigers.Studieshaveshownthatforanimalswithaheightof42cmormore,theverticalpupillosestheadvantage.Therefore,thewilltosurvivehelpstigers,foxesandhorsestoevolvepupilshapessuitablefortheirsurvival.