Treatment DoseWord文档下载推荐.docx
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Treatment DoseWord文档下载推荐.docx
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3.DavidA.Stephens2,
4.AlistairR.Fielder1and
5.onbehalfoftheMOTASCooperative
+AuthorAffiliations
1.1FromtheDepartmentsofVisualNeuroscienceand
2.2Mathematics,ImperialCollegeLondon,London,UnitedKingdom.
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Abstract
purpose.Amblyopiaisthecommonestvisualdisorderofchildhood.Yetthecontributionsofthetwoprincipaltreatments(spectaclewearandocclusion)tooutcomeareunknown.Thisstudywasundertakentoinvestigatethedose-responserelationshipofamblyopiatherapy.
methods.Thestudycomprisedthreedistinctphases:
baseline,inwhichrepeatmeasuresofvisualfunctionwereundertakentoconfirmtheinitialvisualdeficit;
refractiveadaptation:
an18-weekperiodofspectaclewearwithsixweeklymeasurementsoflogarithmoftheminimumangleofresolution(logMAR)visualacuity;
occlusion:
inwhichparticipantswereprescribed6hoursof“patching”perday.Inthelatterphase,occlusionwasobjectivelymonitoredandlogMARvisualacuityrecordedat2-weekintervalsuntilanyobservedgainshadceased.
results.Datawereobtainedfrom94participants(meanage,5.1±
1.4years)withamblyopiaassociatedwithstrabismus(n=34),anisometropia(n=23),andbothanisometropiaandstrabismus(n=37).Eighty-sixunderwentrefractiveadaptation.Averageconcordancewithpatchingwas48%.TherelationshipbetweenlogMARvisualacuitygainandtotalocclusiondosewasmonotonicandlinear.Increasingdoseratebeyond2h/dhastenedtheresponsebutdidnotimproveoutcome.Morethan80%oftheimprovementduringocclusionoccurredwithin6weeks.Treatmentoutcomewassignificantlybetterforchildrenyoungerthan4years(n=17)thaninthoseolderthan6years(n=24;
P=0.0014).
conclusions.Continuousobjectivemonitoringoftheamountofpatchingtherapyreceivedhasprovidedinsightintothedose-responserelationshipofocclusiontherapyforamblyopia.Patchingismosteffectivewithinthefirstfewweeksoftreatment,evenforthoseinreceiptofarelativelysmalldose.Furtherstudiesareneededtoelucidatetheneuralbasisforthedose-responsefunctions.
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Introduction
Amblyopiaisthecommonestchildhoodvisiondisorder,withaprevalenceof1%to5%.1Itcarriesanincreasedlifetimerisk(atleastthreetimesthatofthegeneralpopulation)ofseriousvisionlossofthefelloweye.2Theconditionischaracterizedbyreducedvisualfunctionsand,usuallybutnotinvariably,affectsoneeye.Amblyopiaisfoundinassociationwithoneormoreofthefollowing:
refractiveerror(whichmaybeunilateralorbilateral);
strabismus;
or,morerarely,conditionsthatprecludetheformationofaclearretinalimage(e.g.,infantilecataract).Primatemodelsofamblyopiahaverepeatedlyshowntheprimaryvisualcortex(areaV1)tobedysfunctional.3FunctionalimagingstudiesconfirmprocessingabnormalitiesinareaV1ofhumansandhintatdeficitswithinhighercorticalareas.4
Researchinthe1960sand1970sdemonstratedthatthedevelopingvisualsystemishighlysensitivetodeprivation.5Thisledtotheconceptofavisualsensitiveperiod,endingatapproximately6to7years,which,ifinterruptedbyanyobstaclesuchasblurredvisionand/orstrabismus,resultsinamblyopia.Theclinicalupshotofthisresearchwasthebeliefthatamblyopiashouldbebothidentifiedandtreatedinearlychildhood.Thiscriticalnotionhasinfluencedhealthservicemanagementinmanycountries,sothatintheUnitedKingdomatleast,nationalscreeningforstrabismusandamblyopiaisrecommendedinchildrenagedbetween4and5years6andoverall,approximately90%ofchildren’seyeservicesworkisamblyopiarelated.Suchamassiveinvestmentrequiresthatamblyopiatherapybebotheffectiveandefficient.7
Themainstaytreatmentformorethan250yearshasbeenocclusionofthebettereyebyanopaquepatch(“patching”),topromotevisualfunctionintheamblyopiceye.Therapeuticregimenslackstandardizationandrangefrompatchingforafewminutesadaytoallwakinghours.Treatmentmaylastmanymonths.
Todate,nostudyhasbeenabletoprovidequantitativeinsightintothedose-responserelationshipofocclusiontherapy,animportantprecursortoestablishingtheeffectivenessofatreatmentregimen.Weconsiderthisobservationtobeattributabletoalackofconsiderationofthefollowingfactors:
refractiveadaptation,objectivemeasurementofocclusiondose,andappropriatedefinitionsoftreatmentoutcome.
First,mostchildrenwithamblyopiarequirerefractivecorrectionbyspectaclesaswellaspatching.Bothinterventionsmaygenerateconsiderablevisualimprovement;
however,untilrecently,8theperiodoverwhichwhatisreferredtoaseitheradaptationtospectaclewearorrefractiveadaptationoccurswasnotdefined.Althoughtheimportanceoffullydifferentiatingthebeneficialeffectsofspectaclewearfromthoseofocclusionisnowrecognized,9inpracticebothtreatmentsareoftenprescribedconcurrently.
Second,objectivemeasurementofconcordance(compliance)withtreatmenthasonlyrecentlybecomeavailable.101112Hitherto,anynotionoftreatmentdosewassubjectiveandunquantifiablewithregardtotheamountofactualpatchingreceived(asopposedtothatprescribed).
Third,criticaltoevaluationoftherapeuticeffectivenessisameaningfuldefinitionoftreatmentoutcome.Publishedsuccessratesspanabroadrangefrom19%to93%,1314151617181920butintheabsenceofanagreedconventionofrecordingoutcome,theycannotberigorouslycompared.Twobroadapproachestoquantifyingoutcomehavebeenemployed.Thefirstdefinesoutcomebyvisualacuityachievedattheendoftreatment,often20/20,20/30,or20/40.Theattainmentof20/20presupposes,incorrectly,thatvisualacuityisasinglevalue,ratherthanarange.Theuseofsubnormalvalues(20/30or20/40)isarbitrary.Thesecondapproachdefinesoutcomebythenumberofvisualacuitychartlinesoftreatment-generatedimprovement,buthasthedrawbackthatitoffersnoindicationofhowcloseoutcomeisto“normal,”orhowmuchoftheamblyopiadeficithasbeencorrected.Weconsiderthattheoptimumoutcomeofamblyopiatherapyforunilateralamblyopiaistheachievementofequalvisualacuityinbotheyes,onthebasisthatbinocularvisionisbestpromotedbyequalvisualinputfromeacheye.Utilizingthisapproachinformsbothhowclosetonormalacuitythetreatmentachievesandtheproportionofthevisualdeficitthatiscorrected.21
Herein,wepresenttheresultsoftheMonitoredOcclusionTreatmentofAmblyopiaStudy(MOTAS),withthepurposeofdeterminingthedose-responserelationshipofocclusiontherapyasafunctionofageandtypeofamblyopia.Moststudieshaveyieldedlow-gradeevidenceoftreatmenteffectiveness,generatingaplea22forrandomizedcontrolledtrials(RCTs).Foursuchstudieshavenowbeencompleted23242526;
however,giventhattreatmentsuccesshasbeenclaimedforsuchawiderangeofunmonitoredocclusiondoses,thoseregimenschosenforevaluationbyRCTcanonlyhavebeenselectedonapragmaticbasis.Weproposethatknowledgeofthedose-responsefunctiongleanedbyastudyincorporatingobjectivetreatmentmonitoring(MOTAS)wouldgreatlyinformthedesignoffutureRCTswhileprovidinginterimguidanceonclinicalbestpractice.
Thisstudyisthefirsttoinvestigatetreatmentdose-responseinamblyopiatherapyandwasinnovativeinthatitfullydifferentiatedtheeffectsofrefractiveadaptationfromthoseofpatching,usedobjectivemonitoringofocclusion,andusedrationalmethodsofquantifyingoutcome.
Methods
StudyDesign
Thedesignforthisprospectivestudyhasbeenreportedindetailelsewhere.27Briefly,itcomprisedthreephases:
baseline,refractiveadaptation,andocclusion,depictedindetailinFigure1.
Viewlargerversion:
Inthispage
Inanewwindow
Figure1.
Anorganizationflowchartshowingprogressionofparticipantsthroughthestudy.
Beforestudyentry,allchildrenhadafullophthalmicassessmentincludingcycloplegicretinoscopyandfundoscopy.Thebaselinephasecomprisedaminimumoftwoconsecutiveassessmentstobecertainthatthefirstmeasureoffunctionwasrobust.Childrenwhoneededspectaclecorrectionenteredtherefractiveadaptationphase.Thosenotneedingspectaclecorrectionenteredtheocclusionphase.Childrenwereinstructedtowearspectacles(whereprescribed)fulltimeandwerescheduledtoreturnforvisionassessmentat6-weeklyintervalsfromweek0(onsetofspectaclewear)until18weeksofrefractiveadaptationwascompleted—aperiodthatourpublishedpilotresearchindicatedwouldallowforallsignificantimprovementattributabletospectacleweartohaveoccurred.8Childrenremainingeligible,bystillmeetingthestudy’soperationaldefinitionofamblyopia(describedlater),enteredtheocclusionphaseandwereprescribed6hours’occlusionperday.Occlusionepisodeswererecordedtothenearestminutebyanocclusiondosemonitor(ODM).10TheODM,adevicedevelopedandextensivelypilotedbyus,consistsofaneyepatchwithtwosmallelectrodesattachedtoitsundersurfacethatareconnectedtoabattery-powereddataloggerbyaplastic-encapsulatedwirelead.101128Inthisphase,bothvisualfunctionandmonitoredocclusiondosewererecordedat2-weekintervalsuntilacuityceasedtoimprove(twoinflectionsinanacuity-against-timeplotoridenticalmeasurementsonthreeconsecutivevisits).27Oncompletionoftheocclusionphase,partici
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