简介：AIM:Tocomparethetrabecularmeshwork(TM)andirisapoptosisoftreatedanduntreatedprimaryopenangleglaucoma(POAG)patients.METHODS:Eighttreatment-naive,newlydiagnosed(group1)and11medlcaiytreated(group2)patientswithPOAGwereincludedinthestudy.Eachpatientunderwentalimbus-basedtrabeculectomy.TheTMandperipheralirisspecimensweredissectedoutandweresnap-frozeninliquidnitrogenandstoredat-80tuntiltheywereassayed.ApoptosisineachgroupwasassesedbyTUNELmethod.RESULTS:Themeanpatientagewas60.6±5.8years(53-68years)vs58.9±8.9years(47-70years)ingroup1andgroup2(P=0.859).Themeantreatmenttimeingroup2was22.2±7.3months(12-34months).ApoptoticindexesinTMandirisweresignificantlyhigherinPOAGpatientsusingmedication(group2)comparedtotreatment-naivePOAGpatients(group1)(P=0.004,0.015;respectively).CONCLUSION:LongtermadministrationoftopicalantiglaucomamedicationscausesadditionaltoxiceffectsonTM.

简介：AIM:Toinvestigatetheantifibroticeffectofthefreeze-driedbilayeredfibrin-bindingamnioticmembraneasadrugdeliverysystemonglaucomasurgeryinrabbitmodel.Theaimofthisstudywastoprepareanovellocaldeliverysystemforthesustainedandcontrollablereleaseof5-Fu.METHODS:Twenty-fourJapanesewhiterabbitswererandomizedintothreegroups:theexperimentalgroup(oculartrabeculectomyincombinationwith5-Fuloadedfreeze-driedbilayeredfibrin-bindingamnioticmembranetransplantation),thecontrolgroup(oculartrabeculectomyincombinationwith5-Fu)andtheblankgroup(singletrabeculectomy).HEstaining,massionstainingandimmunohistochemistryforα-SMAwereperformedondays7,14,21and30followingsurgery.Theconcentrationof5-Fuinrabbitaqueoushumorwasexaminedbyhighperformanceliquidchromatography(HPLC)3daysafterthesurgery.RESULTS:Statisticaldifferenceswerenotedinintraocularpressureamonggroupsonday7,14,21and30followingsurgery.Histologyfurtherdemonstratedthattrabeculectomyincombinationwithfreeze-driedbilayeredfibrin-bindingamnioticmembraneyieldedwellwoundhealingandnoscarformationandwasbeneficialforlongtermeffect.CONCLUSION:HPLCshowedagoodslow-releaseeffectwithfreeze-driedbilayeredfibrin-bindingamnioticmembrane.

简介：AIM:Todeterminethehistopathologicalchangesofrifampicinappliedintravitreallyonretinalganglioncellsbymeansofstereologicalandhistopathologicalmethods.METHODS:Forthisstudytwenty-fourNewZealandadultrabbitsweredividedintofourgroups(n=6foreachgroup).50μg/0.1mL(group1),100μg/0.1mL(group2),150μg/0.1mL(group3)and200μg/0.1mL(group4),rifampicinwereinjectedintothevitreousoftherighteyesofanimals,theirlefteyeswereusedascontrol(group5).Afterthe28thdayofapplication,animalswereanesthetisedwithxylazine(8mg/kg,IM)andthentheireyeswereenucleatedimmediately.Patternsweretakenawayandeyeswerepreparedforbothstereologicalandelectromicroscopicobservation.RESULTS:Dependingonthehighdoseofrifampicin,somehistopathologicalchangessuchascytoplasmicdilatationanddamagedmembranewereobservedontheelectromicroscopiclevel.Usingquantitativeexamination,whichwasdoneatthelightmicroscopiclevel,itwasshownthatthenumberofneuronsdecreasedlinearlyasrifampicindoseincreasedwhencomparedwiththecontrolgroup.CONCLUSION:Basedonthesefindings,low-doserifampicin(50μg/0.1mL)maybeusefulfortreatmentoftheoculardiseases.

简介：<正>DearSir,IamDr.Zhong-ShanChenfromtheDepartmentofOphthalmology,WuhanGeneralHospitalofGuangzhouMilitaryCommand,HubeiProvince,China.Iwritetopresenttwocaseswithserpiginouschoroiditis(SC)whichisarare,usuallybilateral,chronic,progressiveinflammationofthechoroid,choriocapillarisandretinalpigmentepithelium.InthispaperwepresentedthedifferentoutcomesofSCpatientswithorwithoutsystemicandoculartreatmentsafterlong-termfollow-up.

简介：AIM:Totestthehypothesisthatamblyopicneuroretinamayhaveanalteredthicknesswhencomparedtothenormal.·METHODS:Twenty-fiveamblyopic,youngpatientsbetweentheagesof7and11yearsoldwerestudied.Theinterestedneuroretinaareasaredefinedinto10sub-regionsaccordingtosuperior-inferior,nasal-temoral,andperi-paraaxis,whichcrossthefovelastructure.Thethicknessesoften,definedmacularregionswereseparatelymeasuredbyopticalcoherencetomography(OCT)andanalyzedbyt-test.·RESULTS:Theaveragethicknessofneuroretinaintheexactfoveolaoftheamblyopiceyesislargerthanthatofnormaleyes(P<0.05),buttheothernineregionshavenosignificantdifference.Interestingly,inboththenormalandamblyopiceyes,thetemporalarealooksthinnerthanotherquadrants(P<0.05).·CONCLUSION:Thicknessalterationmaybeassociatedwithamblyopicdisordersinyoungpatients.Studyingalargervolumeofsubjectsofsimilarageisrequiredtoconfirmthisobservation.

简介：AIM:ToinvestigatetheinterferingeffectofY-27632,aROCK-Iselectiveinhibitor,onthesignaltransductionpathwayoftransforminggrowthfactor-β1(TGF-β1)inocularTenoncapsulefibroblasts(OTFS)invitro.METHODS:AfterOTFSfrompassages4to6invitrowereinducedbyTGF-β1andthentreatedbyY-27632,thechangesoftheOTFScellcycleswereanalyzedviaflowcytometry,andtheproteinsexpressionoftheα-smoothmuscularactin(α-SMA),connectivetissuegrowthfactor(CTGF),collagenIwerecalculatedbyWesternblot.AfterOTFStreatedbythedifferentconcentrationsofY-27632,theexpressionlevelsoftheα-SMA,CTGFandcollagenImRNAwereassayedbyRT-PCR.RESULTS:Y-27632hadnomarkedlyeffectontheOTFScellcycles.AftertreatedbyTGF-β1,OTFSinG1periodsignificantlyincreased.ThecellcyclesdistributionbybothTGF-β1andY-27632hadnoremarkabledifferencefromthatincontrolgroup.Y-27632significantlyinhibitedtheproteinsexpressionsofbothα-SMAandCTGF,whiletosomeextentinhibitedthatofcollagenI.TGF-β1significantlypromotedtheproteinsexpressionsofα-SMA,CTGFandcollagenI.AfterOTFStreatedbybothTGF-β1andY-27632,ofα-SMA,theproteinexpressionwassimilarwiththatincontrolgroup(P=0.066>0.05),buttheproteinexpressionofCTGForcollagenI,respectively,wassignificantlydifferentfromthatincontrolgroup(P=0.000<0.01).Thedifferencesofexpressionsoftheα-SMA,CTGFandcollagenImRNAin30,150,750μmol/LY-27632groupwerestatisticallysignificant,comparedwiththoseincontrolgroup,respectively(α-SMA,P=0.002,0.000,0.000;CTGF,P=0.014,0.002,0.001;collagenI,P=0.003,0.002,0.000).CONCLUSION:BlockingtheRho/ROCKsignalingpathwaybyusingofY-27632couldinhibitthecellularproliferationandtheexpressionofbothCTGFandα-SMAwhateverOTFSinducedbyTGF-β1ornot.Y-27632suppressedtheexpressionofcollagenImRNAwithoutinduction.

简介：<正>DearSir,IamProf.BeuyJoobfromSanitation1MedicalAcademicCenter,Bangkok,Thailand.Iwritetodiscusstherecentpublicationonproteomicanalysisindiabeticretinopathy(DR).Liuetal[1]concludedthattheirapproachbytwodimensionalfluorescencedifferencegelelectrophoresis(2D-DIGE)combinedwithmatrix-assistedlaser

简介：近视性屈光不正已成为眼科最常见的疾病之一,且发病率呈逐年上升趋势,其中高度近视是常见的致盲病因。一般认为近视的发生、发展是由基因遗传和环境因素共同作用的结果。目前对近视的治疗和预防的方法主要包括光学矫正、药物干预和手术干预。如何通过有效的预防方法来降低近视的患病率是当今眼科领域研究的热点和难点。

简介：AIM:Tocomparetheeffectoftopicallyadministeredandsubconjunctivallyinjectedbevacizumabonexperimentalcornealneovascularizationinratsfortwoweeksaftertreatment.METHODS:Twenty-eightSprague-Dawleyratsweredividedintofourgroupsof7animals.Eachcornealcenterofrighteyewascauterizedwithsilver/potassiumnitratefor8s.Aftercornealburning,bevacizumab(12.5mg/mL)wastopicallyadministeredthreetimesperday(TBgroup)fortwoweeksorsubconjunctivallyinjectedondays2and4aftercauterization(0.02mL;SBgroup).Asnegativecontrols,ratsreceived0.9%salinetopicallythreetimesperday(TSgroup)orsubconjunctivallyondays2and4(0.02mL;SSgroup).Digitalphotographsofthecorneaweretaken1and2weeksaftertreatmentandanalyzedtodeterminetheareaofcorneacoveredbyneovascularizationasthepercentageofcornealneovascularization.RESULTS:Oneweekaftertreatment,thepercentageofcornealneovascularizationwassignificantlylowerintheTBandSBgroupsthanintheTSandSSgroups(allP<0.05).Twoweeksaftertreatment,thepercentageofcornealneovascularizationwassignificantlylowerintheTBgroupthanintheTSgroup(P<0.05).Inallgroups,thepercentageofneovascularizationwasdecreasingastimepassed(allP<0.05)CONCLUSION:Topicallyadministeredbevacizumabhaslongerstandinganti-angiogeniceffectthansubconjunctivallyinjectedbevacizumabincornealneovascularizationfollowingchemicalinjuryinrats.

简介：AIM:Tofindouttheoutcomeoflaserphotocoagulationinclinicallysignificantmacularedema(CSME)byopticalcoherencetomography(OCT).·METHODS:Itwasaprospective,non-controlled,caseseriesstudyenrolling81eyesof64patientswithCSMEbetweenAugust2008andJanuary2010.AllpatientsreceivedmodifiedgridphotocoagulationwithfrequencydoubledNd:YAGlaser.Eachpatientwasevaluatedintermsofbest-correctedvisualacuity(BCVA)andregressionorprogressionofmaculopathyafterlasertherapyat1,3and6months.Spearman’scorrelationtestwasusedtoshowthecorrelationbetweenBCVAandtotalmacularvolume(TMV).Analysisofvariance(ANOVA)wasusedtocompareamonggroupsandindependentt-testwasusedtocompareineachgroup.·RESULTS:ThereishighcorrelationbetweenBCVAandTMV(P≤0.001).BCVAimprovedin50.6%,remainedstaticin39.5%anddeterioratedin9.9%patientsafter6monthoftreatment.TheBaselineTMV(meanandSD)were9.26±1.83,10.4±2.38,11.5±3.05,8.89±0.75and9.47±1.98mm3fordifferentOCTpatterns,ST(spongelikethickening),CMO(cystoidmacularedema),SFD(subfovealdetachment),VMIA(Vitreomacularinterfaceabnormality)andaverageTMVrespectively(P=0.04).After6monthsoflasertreatment,themeanTMVdecreasedfrom9.47±1.98mm3to8.77±1.31mm3(P=0.01).InSTtherewassignificantdecreaseinTMV,P=0.01,Furtherwithinthesegroupsat6months,theyweresignificantlydifferent,P=0.01.·CONCLUSION:OCTshowedthedifferentmorphologicalvariantofCSMEwhiletheresponseoftreatmentisdifferent.TMVdecreasedthemostandhenceshowedtheimprovementinvisionafter6monthsoflasertreatment.IntheeraofAntivascularendothelialgrowthfactors(VEGFs),efficacyoflaserseemstobeinshadowbutitisstillfirstlineoftreatmentindevelopingnationlikeNepalwhereantiVEGFsmaynotbeeasilyavailableandaffordable.

简介：Simulationcanbedefinedasmalingering,orsometimesfunctionalvisualloss(FVL).Itmanifestsaseithersimulatinganophthalmicdisease(positivesimulation),ordenialofophthalmicdisease(negativesimulation).Consciousbehaviorandcompensationorindemnityclaimsareprominentfeaturesofsimulation.Sincesomeauthorssuggestthatthisisamanifestationofunderlyingpsychopathology,evenconversionisincludedinthiscontext.Intoday’sworld,everyophthalmologistcanfacewithsimulationofophthalmicdiseaseordisorder.Incaseofsimulationsuspect,thephysician’sresponsibilityistoprovethesimulationconsideringthedisease/disorderfirst,andsimulationasanexclusion.Insimulationexaminations,thephysicianshouldbefirmandsmarttoselectappropriatetest(s)toconvincenotonlythesubject,butalsothejudgeincaseofindemnityorcompensationtrials.Almostallophthalmicsensoryandmotorfunctionsincludingvisualacuity,visualfield,colorvisionandnightvisioncanbethesubjectofsimulation.Examinermustbeskillfulinselectingthemostappropriatetest.Apartfromthoseintheliterature,weincludedallkindsofsimulationinophthalmology.Inaddition,simulationexaminationtechniques,suchas,useofOCT(opticalcoherencetomography),frequencydoublingperimetry(FDP),andmodifiedpolarizationtestswerealsoincluded.Inthisreview,wemadeathoroughliteraturesearch,andaddedourexperiencestogivethereadersup-to-dateinformationonmalingeringorsimulationinophthalmology.

简介：AIM:ToinvestigatethesideeffectsofthecommonlyusedlasertreatmentalongwithtestingtheneuroprotectiveeffectofbFGFonapotentialretinalimpairment.METHODS:Todothis,30chinchillapigmentedadultmalerabbitsweredividedintothecontrolandexperimentalgroups.ThecontrolandexperimentalgroupsunderwentbothlaserapplicationandbFGFtreatment.Theretinaltissueimpairmentanditsrenewalrateweretestedunderthelightandelectronmicroscopicallevels.RESULTS:Thefocallaserapplicationonrabbiteyescausedmorphologicalalterationsbothintheapplicationregionandintheneighbouringareas.Inthedamagedareas,theouternuclearlayeroftheneuralretinawasalmostdisappeared,retinapigmentepitheliumwasinterrupted,theretinapigmentepitheliummigratedintraretinally,andthedamagedregionalongwithneighbouringareasseemedtobenotseparated.bFGFapplicationjustafterthelaserphotocoagulation,revealedbetterresultsinapplicationareas.CONCLUSION:ItcouldbesuggestedthatthebFGFapplicationfollowinglaserphotocoagulationmighthaveprotective,repairingandwoundhealingeffectsontheretina.

简介：AIM:Toevaluatetheaccuracyofsphericalequivalent(SE)estimatesofadouble-passsystemandtocompareitwithretinoscopy,subjectiverefractionandatablemountedautorefractor.METHODS:Non-cycloplegicrefractionwasperformedon125eyesof65healthyadults(age23.5±3.0years)fromOctober2010toJanuary2011usingretinoscopy,subjectiverefraction,autorefraction(AutokeratorefractometerTOPCONKR-8100,Japan)andadoublepasssystem(OpticalQualityAnalysisSystem,OQAS,VisiometricsS.L.,Spain).Nineconsecutivemeasurementswiththedouble-passsystemwereperformedonasubgroupof22eyestoassessrepeatability.ToevaluatethetruenessoftheOQASinstrument,theSElaboratorybiasbetweenthedoublepasssystemandtheothertechniqueswascalculated.RESULTS:TheSEmeancoefficientofrepeatabilityobtainedwas0.22D.SignificantcorrelationscouldbeestablishedbetweentheOQASandtheSEobtainedwithretinoscopy(r=0.956,P<0.001),subjectiverefraction(r=0.955,P<0.001)andautorefraction(r=0.957,P<0.001).ThedifferencesinSEbetweenthedouble-passsystemandtheothertechniquesweresignificant(P<0.001),butlackedclinicalrelevanceexceptforretinoscopy;Retinoscopygavemorehyperopicvaluesthanthedouble-passsystem-0.51±0.50Daswellasthesubjectiverefraction-0.23±0.50D;Moremyopicvalueswereachievedbymeansofautorefraction0.24±0.49D.CONCLUSION:Thedouble-passsystemprovidesaccurateandreliableestimatesoftheSEthatcanbeusedforclinicalstudies.Thistechniquecandeterminethecorrectfocuspositiontoassesstheocularopticalquality.However,ithasarelativelysmallmeasuringrangeincomparisonwithautorefractors(-8.00to+5.00D),andrequirespriorinformationontherefractivestateofthepatient.

简介：·Thisisacasepresentationofaverybizarreopenglobetraumawithanteriorsegmentforeignbody-fishinghookstuckinthecorneaandiris.Complicationsduetothiskindofeyetraumamightbeveryhazardousandwithseriousimpactonvisualfunction.Wearerepresentingourapproachandexperienceofthreestepmanagementofthiskindofeyeinjury:first-extracttheforeignbody,closeandreconstructtheeyeball,second-fightinflammation,andthird-restorethevisualfunctionbycataractsurgery.·

简介：沙眼是由沙眼衣原体感染所致的一种传染性角结膜炎,目前在世界57个国家流行。1998年世界卫生组织（WorldHealthOrganization,WHO）将2020年全球消灭致盲性沙眼（globalalliancetoeliminateblindingtrachomaby2020,GET＆nbsp；2020）列为其防盲工作的主要目标之一。世界卫生组织制定了辨认和命名沙眼的简化分级系统及以社区干预为基础的防治沙眼的SAFE策略,此后10余年各国对此策略进行了不断推广、执行,目前世界上沙眼的流行趋势较之此前有了一定的变化,我国也启动了“计划2016年前在中国根治致盲性沙眼”的防盲工作。本文就SAFE策略推广以来沙眼诊断、治疗及流行趋势等方面的进展做一综述。

简介：AIM:Toevaluatetheefficacy,safetyandstabilityofposteriorchamberphakicintraocularlensimplantationforthecorrectionofhighmyopia.METHODS:Retrospectivecasereviewof82eyes(43patients)undergoingimplantableColiamerlens(ICL)placementbyasinglesurgeon(Xiao-WeiGao)tocorrectpreoperativemeansphericalequivalentsbetween-9.00diopter(D)and-23.00D.Mainoutcomemeasuresincludeduncorrectedvisualacuity(UCVA),refraction,bestspectacle-correctedvisualacuity(BSCVA),endothelialcelldensity(ECD),intraocularpressure(IOP),lenstransparency,postoperativeuveitis.Visanteanteriorsegmentopticalcoherencetomography(AS-OCT)wasusedtomeasureanteriorchamberdepth(ACD)andthepositionofICL.RESULTS:Meanfollow-upwas6.54±3.26months(range3-12months).Predictabilityofthemanifestsphericalequivalent(SE)refractiontowithin±1.OODwasachievedin88%ofeyesand±0.50Din72.5%ofeyes.ThemeanpostoperativemanifestSErefractionwas-1.85±0.72D,with96.34%ofeyesmaintainingorgaining≥1line(s)ofBSCVA.Themean3-monthpostoperativeECDdecreasedbuthadnostatisticallydifferencecomparedwiththepreoperativeECD.Ofthe7eyes(8.54%)withamildtransientincreaseinintraocularpressure(upto30mmHg),nonerequiredasecondsurgicalprocedureorprolongedtopicalmedication.Therewasnolossoflenstransparency.Pigmentedprecipitateswereobservedin5eyes(6.09%).ThemeanpreoperativeACDmeasuredwithAS-OCTwas3.28±0.14mm,threemonthsaftersurgery,themeanACDwas2.45±0.22mm.Anteriorchamberdepthshowedastatisticallysignificantreduction.Oneeye(1.22%)hadICLspontaneousrotation,81eyes(98.78%)ofthelensremainedcorrectlycentered.CONCLUSION:TheimplantationofICLisaneffectivesurgicaloptionforthemanagementofhighmyopia.Butitslongtimeeffectandsafetystillneedmoretimetoprove.

简介：AIM:Todeterminewhethersinglenucleotidepolymorphism(SNP)rs641153isassociatedwiththeriskofage-relatedmaculardegeneration(AMD),weperformedasystematicmeta-analysisof15eligiblestudies.SNPinthecomplementfactorB(CFB)geneisconsideredtohavesignificantassociationwithAMDsusceptibility,butthereisgreatdiscrepancyintheseresults.METHODS:TheeligiblestudieswereidentifiedbysearchingthedatabasesofPubMed,EMBASE,andWebofScience.Oddsratios(ORs)with95%confidenceintervals(CIs)wereusedtoassesstheassociation.AlldatawereanalyzedusingStatasoftware.RESULTS:Theassociationbetweenrs641153andAMDriskwasstatisticallysignificantunderthehomozygousmodel(AAvsGG:OR=0.26,95%CI=0.15-0.45,P_h=0.973,/~2=0.0%,fixedeffects),dominantmodel(AA+GAvsGG:OR=0.49,95%CI=0.40-0.59,P_h=0.004,/~2=56.4%,randomeffects)andrecessivemodel(AAvsGA+GG:OR=0.30,95%CI=0.17-0.51,R_n=0.983,I~2=0.0%,fixedeffects).Thesameresultswerealsoobservedinthestratifiedanalysesbyethnicity,sourceofcontrolandsamplesize.CONCLUSION:Ourmeta-analysissuggeststhatrs641153intheCFBgenemayplayaprotectiveroleinAMDsusceptibility,thelateAMDinparticular,bothinCaucasiansandinAsians.

简介：AIM:ToIntroduceanewspecializedvisualacuitychartforamblyopicchildrenaged3-5yearsoldanditsclinicalapplications.METHODS:ThenewvisualacuitychartandnotationsweredesignedbasedonWeber-Fechnerlaw.Theoptotypeswereredagainstawhitebackgroundandwerespeciallyshapedfourbasicgeometricsymbols:circle,square,triangle,andcross.Aregulargeometricprogressionoftheoptotypesizesanddistributionwasemployedtoarrangein14lines.Theprogressionrateoftheoptotypesizebetweentwolineswas1.2589andthetestingdistancewas3m.VisualacuityscorecouldberecordedaslogMARnotationordecimalnotation.Agestratifieddiagnosticcriteriaforamblyopiaestablishedbyconsensusstatementondiagnosisofamblyopia(2011)amongmembersoftheStrabismusandPediatricOphthalmologyGroup,OphthalmologySociety,ChineseMedicalAssociation(SPOGOSCMA)wereillustratedinthenewvisualacuitychart.RESULTS:Whenassessingvisualacuityinchildrenaged3-5yearsold,thisnewvisualacuitychartthatconsistsoffoursymmetricalshapes(triangle,square,cross,andcircle)overcameaninabilitytorecognizethelettersofthealphabetanddifficultiesindesignatingthedirectionofblackabstractsymbolssuchasthetumbling’E’orLandolt’C’,whichthesubjectswerepronetoloseinterestin.Thevisualacuityscoremayberecordedindifferentnotations:decimalacuityandlogMAR.Thesetwonotationscanbeeasilyconvertedeachotherintheneweyechart.Themeasurementsofthisnewchartnotonlyshowedasignificantcorrelationandagoodconsistencywiththeinternationalstandardlogarithmicvisualacuitychart(r=0.932,P<0.01),butalsoindicatedahightest-retestreliability(89%ofretestscoreswerewithin0.1logMARunitsoftheinitialtestscore).CONCLUSION:Theresultsofthisstudysupportthevalidityandreliabilityofdistancevisualacuitymeasurementsusingtheneweyechartinchildrenaged3to5yearsoverawiderangeofvisualacuities,andtheneweyechartisgreatforearl

简介：验光的目的在于获得清晰的视力,舒适的阅读跟持久的用眼。双眼平衡检查是指在验光时分别测得单眼MPMVA是否支持双眼同时的视觉活动加以检验和调整,最终达到使屈光不正者获得双眼屈光平衡及调节平衡,使屈光不正者真正获得清晰、舒适和持久的视力。双眼平衡的方法包括,棱镜分离法,交替遮盖法,偏振分离法,以及偏振红绿法等。

简介：医疗系统的前景是什么？作为眼科医疗工作者,我们不仅要治疗眼睛,我们更要治疗患者。同样,眼科医疗并非在真空中作业,而是从属于更宽泛的医疗保健系统。当我们的工作需要如此之多的人力之时,很可能让人忘记工作的大背景是什么。然而,