Selective laser trabeculoplasty: past, present, and future | Eye

Over the past two decades, selective laser trabeculoplasty (SLT) has increasingly become an established laser treatment used to lower ... Skiptomaincontent Thankyouforvisitingnature.com.YouareusingabrowserversionwithlimitedsupportforCSS.Toobtain thebestexperience,werecommendyouuseamoreuptodatebrowser(orturnoffcompatibilitymodein InternetExplorer).Inthemeantime,toensurecontinuedsupport,wearedisplayingthesitewithoutstyles andJavaScript. Advertisement nature eye reviewarticles article Selectivelasertrabeculoplasty:past,present,andfuture DownloadPDF ACorrectiontothisarticlewaspublishedon23October2019 Thisarticlehasbeenupdated AbstractOverthepasttwodecades,selectivelasertrabeculoplasty(SLT)hasincreasinglybecomeanestablishedlasertreatmentusedtolowerintraocularpressureinopen-angleglaucomaandocularhypertensivepatients.InthisreviewwetracetheoriginsofSLTfrompreviousargonlasertrabeculoplastyandreviewthecurrentroleithasinclinicalpractice.WeoutlinefuturedirectionsofSLTresearchandintroduceemergingtechnologiesthatarefurtherdevelopingthisinterventioninthetreatmentparadigmofglaucoma. DownloadPDF IntroductionGlaucomaisaprogressivemultifactorialdiseasecharacterisedbydamagetotheopticnerve.Itisstronglyassociatedwithelevatedintraocularpressure(IOP)butmayalsooccurwithIOPinthenormalrange.Glaucomaresultsinprogressivevisualfieldlossandisaleadingcauseofblindnessworldwide,secondonlytocataract.Itispredictedthatbytheendofthedecade,closeto80millionpeoplewillhaveglaucoma,themajorityopen-angleglaucoma(OAG)[1].ThemainstayofglaucomatreatmentisloweringofIOPtosloworpreventfurtherprogressionandvisualloss.Thismaybeachievedbyeithermedical,laser,orsurgicalmeans.Overthepasttwodecades,selectivelasertrabeculoplasty(SLT)hasincreasinglybecomeanestablishedtreatmenttolowerIOPinOAGandocularhypertensivepatients.Inthisreview,wetracetheoriginsofSLTfromargonlasertrabeculoplasty,reviewthecurrentroleofSLT,andoutlinebothfuturedirectionsofresearchandemergingtechnologies.PastLaserswerefirstusedtolowerIOPinthe1970swithearlyattemptsmeetinglimitedsuccess.GoniopunctureusingtheQ-switchedrubylaserproducedatemporaryIOPreduction,whilsthigh-energyargonlaserphotocoagulationofthetrabecularmeshwork(TM)causedacutepost-laserIOPspikes[2].WiseandWitter[3]usedargonlaseratlowerenergylevelsandreportedsuccessfulshort-termIOPreductionby~10 mm Hgin40phakiceyes,despite65%oftheseeyeseventuallyrequiringadditionalmedication.AndersonandParrish[4]foundthatappliedradiationenergycouldbeselectivelyabsorbedbyapigmentedcellpopulationwithinatissuetocauselocaliseddamage;aprocessknownasselectivephotothermolysis(SP).Theinherentpropertiesofthetissueprovidedtargetselectivity,reducingcollateraldamage.SPhadtwoprinciplerequirements;thedesiredtargetneededanintracellularchromophorewithgreateropticabsorptionatthelaserwavelengththansurroundingtissue.Second,laserdurationcouldnotexceedthetimerequiredforthermaldiffusionintothetissue(thermalrelaxationtime)[5].ALTfulfilledthefirstrequirementofSP,asmelaninwithinthepigmentedTMactedasthechromophore.However,thelaserdurationofALT(~0.1 s)waslongerthanthethermalrelaxationtimeofmelanin(1 μs)allowingheatgeneratedwithinpigmentedcellstodissipateanddamagesurroundingTM[5].ALT:mechanismofactionIOPreductionseeninALTwasmediatedbyanincreaseinaqueousoutflow,confirmedbybothtonographicandaqueousdynamicstudies[6,7].Amechanicalmechanismwaspostulatedinwhichlaser-inducedthermalburnsoftheTMcausedcollagenandtissuecontraction.Thisreducedthediameteroftheinnertrabecularring,reversingcollapseofthemeshworkthusmaintainingaqueousoutflow[3].ElectronmicroscopydemonstratedfocalcoagulativeTMdisruptionwithconnectivetissueandcellulardebrisdepositedwithintheintra-trabecularspaces[8].Importantly,ultrastructuralTMchangesoccurredbeforeIOP-loweringresponse,suggestingthemechanismofactionwasunlikelytobebymechanicalmeansalone.‘Biological’theoriesweresuggestedonceALTwasfoundtomodifylocalcellularsignallingpathwaystoenableincreasedaqueousoutflow[9].ALT:efficacyALTinducedaninitial30%reductioninIOP.Theresponseseemedrelatedtopre-treatmentIOPandthuseyeswithnormaltensionglaucoma(NTG)showedasmallereffect[2].ALTwassuccessfulasbothprimarytreatment[10]andasanadjuncttomaximalmedicaltreatment[6]withIOPreductionsreportedbetween6.4and9.7 mm Hg(26–33%).Therewerelimitations:theeffectofALTdiminishedovertime.Schwartzetal.[11]performed360°ALTon72patientswithuncontrolledOAGonmaximalmedicaltreatmentandfoundthe77%successrateat2yearshadfallento46%at5years.SpaethandBaez[12]treated109eyeswithuncontrolledOAGonmaximalmedicaltreatmentwithALT:32%neededfiltrationsurgeryat1year,65%at5years,and95%at10years.Failurewashighestinthefirstyearandsubsequentlyoccurredat10%peryear[13].ThesuccessofALTinfailedeyeswasalsolessthanwithinitialtreatment.Richteretal.[14]performed180°ALTretreatmentto40eyesthathadpreviouslyundergone360°ALTandfoundonly32%ofeyesdemonstratedatleast3 mm HgreductioninIOP.BaselinepredictorsofALTsuccesswerehigherpre-treatmentIOPandincreasedage.Racewasalsorelevant:blackpatientshadalowersuccessrate(32%)at5yearscomparedtowhite(65%)[11].PigmentaryandexfoliativeglaucomashowedsimilarefficacytoprimaryOAG(POAG),butthelargestIOPreductionsandearlierfailureswerenotedinexfoliativeglaucoma.OtherformsofsecondaryOAGhadlimitedresponsetoALTwithuveiticanddevelopmentalglaucomasoftenshowinglittleornousefulfallinIOP[15].ALT:adverseeffectsThemainadverseeventsrelatedtoALTweretransientacuteIOPspikesfollowinglaser,developmentofperipheralanteriorsynechiae(PAS),cornealendothelialchanges,andacuteanterioruveitis[2].Inonestudyof271eyes,ariseofmorethan5 mm Hgoccurredin34%ofpatientsandofmorethan10 mm Hgin12%after180°ofALT[16].ThefrequencyandseverityofIOPelevationswerepositivelyassociatedwithhigherenergylevels,360°treatment,moreposteriorplacementofburns,greateranglepigmentation,andalowpreoperativeoutflowfacility.Mostpost-treatmentIOPpeaksoccurredwithin2 handwerepostulatedtobeduetoTMswellingorobstructionofthetrabecularspacesbydebris[17].DevelopmentofPASwasanotherimportantcomplication,notedmorefrequentlywithhigherpowers[18].OnestudyfoundathreetimeshigherincidenceofencapsulatedblebsineyespreviouslytreatedwithALT(15.4%)comparedtoeyeswithoutlaser(4.7%)[19].RoleofALTThebenefitofALTwasasanoutpatientprocedurethatwasquick,welltolerated,andsafe.Itavoidedtheinconvenienceandsideeffectsofregularmedicaltreatmentanddelayedtherisksofsurgery.However,lossofeffectwithtimeandassociationwithblebencapsulationindrainagesurgerymeantALTwasconsideredanadjuncttomaximaltoleratedmedicaltreatmentandameansofdelayingsurgery.OnepivotalstudyevaluatedALT’sroleasaprimarytreatment:TheGlaucomaLaserTrialResearchGroupfoundbetterIOPcontrolwithALTalonecomparedtoasinglemedicationat6months,1year,and2yearsbutinferiorcontrolat5yearsoriftwomedicationswereused[10].Comparedtosurgery,trabeculectomyachievedsignificantlylowerIOPswithreduceddiurnalIOPfluctuation[20].PresentSLT:introductionIntroducedbyLatinaandParkin1995,SLTusesa532 nmQ-switched,frequency-doubledNd:YAGlaserthatdeliversashorterpulseduration(3 ns).ItsatisfiesthedualcriteriaofSP,preventingheatdissipationoutsideofpigmentedTMcellsandcausinglesscollateraldamage[21].SincereceivingFDAapprovalin2001,SLThasincreasinglybeenadoptedintopractice.IntheUSA,75 647trabeculoplastieswereperformedin2001,andthisfigurehadincreasedto142 682proceduresin2012[22].Thebenefitsareclear.Theprocedureisshort,outpatient-basedwithquickrecoveryandgoodsafetyprofile.TheroleofSLTinthetreatmentofglaucomaisstillnotwelldefined.InthissectionwereviewtheliteraturetogivecurrentperspectivesonaspectsrelatedtoSLTrelevanttoitsroleinclinicalpractice.SLT:mechanismofactionTonographicandaqueousdynamicstudieshavedemonstratedthatSLTincreasesaqueousoutflowthroughtheTM[23,24].HistopathologicalcomparisonsofhumaneyesthathaveundergoneSLTvsALT[25]reportlesserdisruptiontotheTMineyespostSLT.HigherpowerSLTcancausemoreextensiveTMdamagethanlowerpowersuggesting[26]thatdamagecouldbeenergydose-dependent.SincelimitedstructuraldamageoccurstotheTM,themechanicalandstructuraltheorieswhichhavebeensuggestedtoexplainALT’smechanismofactiondonotfullyapplytoSLT.Moreover,SLThasbeendemonstratedtoinducebiologicalchangesthatmodulateincreasedaqueousoutflowthroughtheTM,includingchangesingeneexpression,cytokinesecretion,matrixmetalloproteinaseinduction,andTMremodelling[5].Usingmicroarrayanalysis,SLThasbeenshowntomodulateexpressionofgenesrelatedtocellmotility,extracellularmatrixproduction,membranerepair,andreactiveoxygenspeciesproduction[27].Invitrostudieshavedemonstratedanincreaseinpro-inflammatorycytokineexpression,includinginterleukin-1-alpha,interleukin-1-beta,tumournecrosisfactor-alpha,andinterleukin-8postSLT[9].Thesecytokinesincreasestromelysin-1expression(MMP-3),amatrixmetalloproteinaseimplicatedinTMextracellularmatrixremodellingtoincreaseaqueousoutflowthroughthejuxtacanalicularmeshwork[28].IncreasedTMmonocyterecruitmenthasalsobeennotedpostSLT,aresultofincreasedchemokineproduction[29].MonocytesincreaseaqueousoutflowinvivoandincreaseSchlemm’scanalpermeabilityinvitro,byfurthercytokinesecretionordirectlyphagocytosingdebriswithintheTM.Localincreasesinendothelin-1arethoughttocontributetotheacuteIOPriseseenpostSLT[30]whilstrisesinlipidperoxidelevelsanddecreaseinantioxidantenzymesmaybeduetotheincreasedinflammatoryresponseprecipitatedafterlaser[31].InvitrostudiesdemonstratethatSLTandprostaglandin(PGA)analoguesmayshareacommonpathwayofactionbyinducingintercellularjunctiondisassemblyinSchlemm’scanalandTMcellsthusincreasingaqueouspermeability[32].ClinicaltechniqueLasertreatmentSLTisperformedusingtopicalanaestheticandagonioscopiclenswithcouplingmedium.Thespotsize(400 microns)isfixedbutnumberofshots,energylevel,andthereforetotalenergydeliveredarevariable.Intheirpilotstudy,Latinaetal.[21]used50non-overlappingshotsplacedover180°oftheTM.Theenergylevelwassetat0.8 mJanddecreasedby0.1 mJincrementsuntilnovisibleeffectsorbubbleswereobserved.Incurrentpractice,typicaltreatmentparametersare50–100shotsappliedover180°–360°withenergyadjustedto0.6–1.4 mJandanendpointofjustvisibletissuereactionorsmallmicrobubbles.StudieshaveevaluatedwhethertreatingdifferentdegreesoftheTMwithSLTinfluencesIOPlowering.Chenetal.[33]comparedOAGpatientsthatreceived90°SLTvs180°SLTandfoundnosignificantdifferenceinIOPsat1,4,and7monthsbetweengroups(P=0.21).InaRCTcomparing180°SLTvs360°SLTinpatientswithuntreatedPOAG/OHT,meanIOPreductionat1monthwas6.9and8.2 mm Hginthetwogroupsrespectively,withnosignificantdifferencenoted(P=0.35)[24].Nagaretal.[34]comparedIOPloweringof90°,180°,and360°SLT,andfoundnodifferencebetween180°and360°SLTtreatmentsat12months’follow-up[34].Bothgroupsweremoreeffectivethanthe90°SLTgroup.Energysettingshavealsobeeninvestigated.Tangetal.[35]compared39patientsreceiving100shotsof360°SLTusinglowenergysettings(0.3–0.5 mJ)vs35patientswhoreceived100shotsof360°SLTusingstandardenergysettings(0.6–1.0 mJ).NodifferenceinIOPloweringbetweengroupsatalltimepointsupto1yearwasnoted.Furthermore,therewasreducedincidenceofadverseeventsinthelowerenergygroup.Incontrast,Leeetal.[36]foundgreatertotalSLTenergywasassociatedwithagreaterIOPlowering,butthisstudywaslimitedbysmallsamplesize(n=49eyes,1eyeperpatientanalysedfrom25NTG,24POAGpatients)andshortfollow-upduration(1month).Arecentstudyhasevaluatedusingashorterlaserpulsedurationof1 nscomparedtoconventional3–5 nsandfoundnodifferenceinIOPloweringoradverseeventsbetweenthetwoarmsintreatment-naivePOAG,OHT,andNTGpatientswith6-monthfollow-up[37].PostlasertreatmentTopicalIOP-loweringmedicationsareroutinelyprescribedpreoperativelyorimmediatelypostSLTtopreventIOPspikes.Ameta-analysisof22trialsinvolving2112patientsinvestigatedtheefficacyofperioperativemedicationstopreventincreasedIOPpostlaser[38].PatientsreceivingmedicationhadalowerriskoftheIOPincreasingby10 mm Hgormorewithinthefirst2 hcomparedwiththosereceivingnomedicationorplacebo(riskratio(RR)0.05,95%confidenceinterval(CI)0.01–0.20)andupto24 h(RR0.22,95%CI0.11–0.42).Therewasnoadvantagetomedicationbeingadministeredbeforeorafterlaserandnodifferenceineffectivenessbetweendifferentalpha2-agonists.Topicalanti-inflammatorydropsarecommonlyprescribedposttrabeculoplastytomitigateearlyinflammation.AsSLT’seffectsarepurportedtoactpartlyviaabiologicalpathway(includingproductionofpro-inflammatorycytokines),thepotentialcounter-productivenatureofprescribingtopicalanti-inflammatorieshasbeenconsidered.AprospectiveRCTof132eyesevaluatedusageoftopicalindomethacin0.1%ordexamethasone0.1%TDSfor1weekvscontrol(notreatment)postSLT[39].Nostatisticallysignificantdifferenceinanteriorchamberreaction,conjunctivalredness,reportedpain,orIOPloweringbetweengroupsatalltimepointswasfound.Thissupportspreviousstudiesthathaveconcludedanti-inflammatorydropsafterSLTdonotcauseasignificantreductionininflammationoralteredIOP-loweringefficacy[40,41].ClinicalefficacyofSLTinPOAGandOHTpatientsThefirstSLTefficacydatareportedbyLatinaetal.[42]whotreated180°ofTMdemonstrated6 mm HgmeanIOPreductioninuncontrolledPOAGeyespreviouslytreatedwithALTand5.8 mm HgineyeswithoutpriorALT.Overall,70%ofeyesexhibitedanIOPreductionof≥3 mm Hg.AverageIOPreductionfollowingSLTisreportedtobe21.8-29.4%at6months,16.9–30%at12months,7.7–27.8%at2years,24.5–25.1%at3years,23.1–29.3%at4years,22.6–32.1%at5years,and22.8%at6years[43].TheIOP-loweringeffectofSLTdiminisheswithtime.OnthebasisofthecommonlyadoptedsuccesscriteriaofIOPreduction>20%frombaselineIOP,successratesvaryfrom66.7to75%eyesat6months,58to94%at12months,40to85%at2years,38to74%at3years,38to68%at4years,and11.1to31%at5years[43].SLTvsALTinOAG/OHTpatientsTodate,thereareatleast10RCTscomparingSLTvsALT[44].AllstudieshavereportednodifferenceinIOPreductionbetweenthetwotreatments.Ameta-analysis[45]evaluatedfourRCTscomparingefficacyofSLTandALT[46,47,48,49].StudiesincludedpatientswithPOAG,pseudoexfoliation(PXF),pigmentdispersionsyndrome,uveiticglaucoma,andNTG.Inallstudies,patientshaduncontrolledIOPdespitemaximallytoleratedmedicaltreatmentorpreviousALT.Patientsreceived180°oftreatmentinbothgroups.Overall,therewasapooledtotalof150eyesintheSLTgroupand140eyesintheALTgroup.Definitionofsuccessvariedbetweenthestudies.Threeoutoffourstudiesaimedfor>20%IOPloweringwithoutneedforfurthersurgery[46,47,49],whereasonestudywaslessstringent—optingfor15%IOPreduction[48].DifferenceinpooledmeanIOPreductionbetweenbothgroupswasnotsignificantat−0.5 mm Hg(95%CI:−1.5 mm Hg,0.4 mm Hg).Twostudies[46,47]assessingtheeffectofSLTandALTonreducingthenumberofmedicationsrequiredfoundnosignificantdifferenceandtreatmentsuccessforSLTandALTwassimilarbetweenbothgroups(P>0.05).Overall,SLTdemonstratedcomparableefficacywithALTinpatientsonmaximallytoleratedmedicaltreatment[45].Thesefindingsagreewithtwopreviousmeta-analysesevaluatingSLTvsALT[50,51].Athirdmeta-analysis,comprisingof6studiesreportedSLTtohaveasuperiorIOPloweringefficacytoALT[52].Thisdifferencecouldhavearisenasthismeta-analysisalsoincludedquasirandomisedcontrolledtrialsaspartoftheiranalysis.SLTvstopicalmedicationinOAG/OHTpatientsMultipletrialshavecomparedSLTagainsttopicalmedicationintreatingOAGandOHTpatients[44].WithinSLTgroups,thereisoftenvariabilityinthedegreeofTMtreated.Commonparametersusedbystudiesinclude900,1800or3600SLT.Nagaretal.[34]performedaRCTcomparing90°,180°,and360°SLTvslatanoprostinOAG/OHTpatients.Successratesweresignificantlyhigherinthelatanoprostgroupcomparedtothe90°and180°SLTgroupsbutsimilartothe360°SLTgroup.ThiswasconfirmedinasubsequentRCTwhere20patientsreceiving360°SLTwerecomparedagainst20patientstaking0.005%latanoprost[53].SLTdecreasedIOPby4.7 mm Hg(95%CI3.6–5.7 mm Hg;P<0.01)withasimilarreductionfromlatanoprost.BothwerefoundtoreducediurnalIOPfluctuationwithnodifferenceintreatmentsuccessatlastfollow-up(4–6months)betweengroups(P=0.4).Todate,twometa-analysescomparingSLTwithmedicationhavebeenperformed[45,54].BothincludefourRCTs,butLietal.[54]alsoincludedonefurtherprospectivenon-randomisedtrial[55].Infouroutoffivestudies,360°SLTwasperformed.Inthreeofthefivestudies,themedicationarmconsistedofPGAmonotherapy[34,53,55],whereasintheothertwostudies[56,57],differenttopicalagents,includingcombinationdropswerepermittedtobeused.Definitionofsuccessvariedbetweenstudies—fourstudiescomparedSLTwithmedication(eitherPGAmonotherapyordifferenttopicalmedicationsusedincombination)intermsofIOPreductionwhilstonestudyclassifiedsuccessasmeetingatargetIOP.WhenusingIOPreductionasasuccesscriterion,onestudychoseIOPreductionasIOP<21 mm Hgafterintervention[56]whilsttheremainingthreeusedatleast20%IOPreductionfrombaseline[34,53,55].Analysisincluded492eyesof366patientswithOAG.SLTshowednosignificantdifferenceinIOPreductioncomparedtomedication(eitherPGAmonotherapyordifferenttopicalmedicationsusedincombination)(weightedmeandifference0.6,95%CI:−0.24,1.43).Therewasnosignificantdifferenceinachievingtargetend-pointsuccessratesbetweengroups(pooledOR0.84,95%CI:0.42,1.68).SimilaranalysesperformedbyWongetal.[45]alsodemonstratednosignificantdifferencebetweenSLTandmedication(eitherPGAmonotherapyordifferenttopicalmedicationsusedincombination).Insummary,meta-analysisdatasuggestsSLTisaseffectiveasmedication(eitherPGAmonotherapyordifferenttopicalmedicationsusedincombination)forIOPcontrol,withsimilarsuccessrates.Limitationstoconsiderincludedatabeingderivedandpooledfromtrialsofdifferentdurationswithmissingdataduringfollow-up,aswellasdifferentdefinitionsbeingusedtodefinesuccess.SLTvssurgicaltreatmentsinOAG/OHTpatientsNostudieshaveevaluatedSLTagainstglaucomasurgery.ALThaspreviouslybeenevaluatedagainsttrabeculectomyandfoundtobeinferioratIOPlowering[20].SimilarcomparisonswithSLTwouldbeexpectedtoyieldsimilarresults.TheAGISstudylookedattheimpactoftimingofALTbeforeversusaftertrabeculectomyandfoundnodifferenceforwhitepatients,butasmalladverseimpactofpriorlaserontrabeculectomyfunctionforblackpatients[58].Morerecently,Feaetal.[59]compared25eyesreceivingSLTvs31eyesreceivingplacementofHydrusmicrostent,amicroinvasiveglaucomasurgery(MIGS)device.At12months,asignificantdecreaseinIOPwasnotedinbothgroups.ComparisonbetweengroupsrevealednosignificantdifferenceinmeanIOPreductionbutathreefoldgreaterreductioninmedicationuseinthehydrusgroupcomparedwithSLTwasfound(−1.4±0.97vs−0.5±1.05,P=0.001).Forty-sevenpercentofpatientsweremedication-freeat12monthsinthehydrusgroupvsonly4%intheSLTgroup.Ahigherfrequencyofpostoperativecomplicationswereseeninthehydrusgroup—threepatientsexperiencedatemporaryreductionofvisualacuitypost-operativelyandtwopatientshadpostoperativeIOPspikesvsnocomplicationsnotedintheSLTgroup.TheseresultssuggestMIGSdeviceshaveasimilarIOP-loweringefficacytoSLTandcanreducethenumberofmedicationsthatpatientstake.However,MIGSinsertionisasurgicalprocedureperformedintheatreassociatedwithanincreasedadverseeventprofile.FurtherstudiesareneededtofullycompareMIGSwithSLTtoevaluateeffectiveness,safety,andcost.SLTasprimarytreatmentinOAG/OHTpatientsMoststudiesinvestigatingprimarySLThavecomparedefficacyagainsttopicalmedication.Theyhavefound‘primary’SLTtohaveasimilarIOP-loweringefficacyandsuccessratetotopicalmedicationusingavarietyofsuccesscriteria.Manyofthesestudieshaveincludedpatientstakingtopicalmedicationsstoppedforavariableduration(4weeksto3months)beforeSLT[34,47,55].Suchpatientsarenottrulytreatment-naive.Despiteawashoutperiodtomitigateagainstresidualeffectsofpriortopicaltreatment,somestudieshaveshownSLTtobelesseffectivewhenusedfollowingtopicaltreatment.McIlraithetal.[55]reportedclinicaloutcomesin87eyesontopicalglaucomamedicationdiscontinued4weeksbeforeSLT.IOPreductionwassignificantlylesscomparedtothetreatment-naivegroup(8.1vs6.4 mm Hg,P<0.001).ExplanationsincludeinadequatewashouttimeorsimplythatSLTismoreeffectiveasaprimarytreatment.SLTasadjuncttreatmentinOAG/OHTpatientsSimilartoALT,SLThasalsobeeninvestigatedasanadjuncttreatmentforpatientsonconcurrenttopicaltherapyasameansoffurtherIOPreduction.Weinandetal.[60]reportedclinicaloutcomesof52POAGeyesthatreceivedadjunctSLTwhilstontopicalmedicaltreatment.AverageIOPreductionfrombaselinewas24.3%(6.0 mm Hg)at1year,27.8%(6.12 mm Hg)at2years,24.5%(5.53 mm Hg)at3years,and29.3%(6.33 mm Hg)at4years.InaRCTof41medicallycontrolledPOAGpatientsevaluatingtheeffectofadjuvantSLTvsmedicationalone[61],at6months,averageIOPpostSLTwas7.6%lowerthanthemedicationgroup(P=0.03)withtheSLTgrouprequiringsignificantlyfeweranti-glaucomamedicationscomparedwiththemedicationgroup(P=0.02).AdjunctSLTinPOAGpatientswithuncontrolledIOPsdespitemedicaltherapyhasalsobeenshowntobeeffective[62,63],whilstotherstudieshavedemonstratedareductioninnumberofconcurrentglaucomamedicationsneededtocontrolIOPfollowingSLT[62,64].Wooetal.[65]investigatedtheeffectsofconcurrenttopicalmedicationonefficacyoffirst-timeadjunctSLT.Patientsweregroupedintodifferentgroups(0–3)basedonthenumberofmedicationstheyweretakingbeforeSLTandthenfollowedforupto5years.AverageIOPreductionfollowingSLTvariedbetween21.8and29%acrossallgroupsat6months,andbetween23.6and25.6%at5yearswithnostatisticallysignificantdifferencenotedbetweengroups.Mixedmodelanalysisdemonstratednosignificantinteractionsbetweennumberofmedicationsandpost-treatmentIOPresponseovertimeandwasinagreementwithpreviousstudiesdemonstratingthis.Importantlyhowever,ofthe206patientsinitiallyinthestudy,only55patientsremainedat5yearsduetolosstofollow-upandpatientsrequiringadditionalintervention.Thismakesinterpretationofthelonger-termoutcomesdifficultandreiteratesthattheeffectofSLTislargelytemporary.SLTfollowingothertreatmentinterventionsSLTiseffectiveasanadjunctinpatientswhohavepreviouslyundergoneALT.MeanIOPreductionat1yearin30OAGpatientsreceivingprimarySLT(23%)wasnodifferentto27OAGpatientsreceivingSLTafterpriorALT(19.3%)[66].Zhangetal.[67]investigatedtheefficacyofSLTinadvancedPOAGpatientswhodespiteprevioustrabeculectomyhaduncontrolledIOPsrequiringadditionaltopicaltreatment.In18eyes,meanIOPwasreducedfrom21.3to16.2 mm Hgatlastfollow-upwith77.7%ofpatientsachievingareductionof>20%frompre-treatmentIOP.Thestudywassmallwithashortfollow-up(9months)limitingtheconclusionsthatcanbemade.Inconclusion,SLTiseffectiveasanadjunctinOAGpatientsonmedicaltreatment.ItiseffectiveatdelayingtheneedforsurgeryinuncontrolledOAGpatientsbutalsomayhavearoleinpost-surgicalpatientsasameansoffurtherIOPreduction.IOPfluctuationreductionwithSLTLargediurnalIOPfluctuationsareconsideredbysometobeanindependentriskfactorforglaucomaprogression[68].Nagaretal.[53]reportedthatSLTandPGAsaresuccessfulatreducingIOPvariationinPOAGpatientsoverthewholefollow-upperiod,butPGAsaremoreeffective(3.6 mm Hg,95%CI3.2–3.9vs2.5 mm Hg,95%CI2.2–2.9 mm Hg,P=0.04).Kiddeeetal.[69]confirmedthisinPOAGandNTGpatients,andalsodemonstratedthatPGAsreduceIOPfluctuationthroughouta24 hperiod,whereasSLT’seffectispronouncedatnight.TheextentofSLTtreatmentmayalsoinfluenceIOPfluctuation[70]with360°SLTbeingshowntoreduceIOPfluctuation>180°treatment.Contactlenssensors(CLS;SENSIMEDTriggerfish,Sensimed,Switzerland)havebeenusedtocontinuouslymeasurechangesinoculardimensionsover24hourswhicharetheninterpretedasbeingrelatedtofluctuationsinIOP.At1monthafterlaser,in18NTGpatientstreatedwith360°SLT[71]whohadachievedtreatmentsuccess(≥20%IOPreduction),therewasa24.6%reductionin24 hIOPvariability,whereasinunsuccessfulpatients,theIOPvariabilityincreasedby19.2%.ThisdifferstoastudybyTojoetal.[72]whoalsoinvestigated24 hIOPfluctuationsusingCLSin10NTGpatients.TheyfoundtherangeofIOPfluctuationswasnotsignificantlychangedbetweenpreandpostSLTover24 h(P=0.77)orduringthedaytimediurnalperiod(P=0.92),buttherangeofIOPfluctuationsduringnocturnalperiodswassignificantlydecreased(P=0.014).SLTwasthusshowntosignificantlylowerIOPanddecreasenocturnalIOPfluctuationsinNTGpatientssupportingthefindingsofKiddeeetal.[69]RepeatibilityofSLTTheIOP-loweringeffectofSLTdiminisheswithtime.AsSLTcausesminimalstructuralTMdamage,repeattreatmenthasbeenconsideredfeasibleinsuitablepatientsrequiringfurtherIOPreduction.Todate,sevenstudiesreportoutcomesofrepeat360°SLT.Ayalaetal.[73]performedaRCTtoevaluatetheeffectofrepeatSLTinPOAG/PXFglaucomapatients.Patientsweretreatedinitiallywith180°SLTinthelowerhalfoftheTMandthenrandomlyreceivedfurtherSLTinthepreviouslytreatedTMorinthe180°upperuntreatedTM.Inall,40patientswereincludedinbothgroups.ThestudyfoundnosignificantdifferencesinIOPbetweentheretreatmentgroupsatalltimepointsbutfollow-upwasonly6months(P=0.66).ThissuggestsrepeatSLTcanbeappliedtoanyTMareawithsimilarefficacyandsupportsthetheorythatSLTretreatmentissimilarlyeffectivetoprimarytreatment.Francisetal.[74]retrospectivelyevaluated137eyeswithPOAGorsecondaryOAG(excludinguveiticglaucoma)thathadundergonetwo360°SLTtreatmentsatleast6monthsapart.PercentageIOPreductionbetweenthetwotreatmentsat12–15monthswasnotsignificantlydifferent(14.5vs10.9%,P=0.11).Asub-analysisof62patientswherebaselineIOPswerematcheddemonstrated20%successat12monthsfollowingbothinitialandrepeatSLT(successcriteria:IOPbetween5and21 mm HgandIOPreduction≥20%frombaselineat12months).Hongetal.investigated44eyeswithuncontrolledOAGonmaximumtoleratedmedicaltherapywhereprimary360°SLThadinitiallybeensuccessful(successcriteria:≥20%peakIOPreduction).Repeat360°SLTachievedsuccessin43.2%ofeyesat5–8monthscomparedto50%successatinitialSLT[75].TherewasnostatisticallysignificantdifferencebetweenprimarySLTandrepeatSLTsuccessrates.ThesefindingsaresupportedbyPolatetal.[76],whoperformedaretrospectivereviewof38eyeswithOAGuncontrolledonmedicaltherapythathadundergonetwosuccessive360°SLTtreatments.TheyfoundasignificantIOPreductionfrombaselineafterbothtreatmentsupto24months’follow-up.Kaplan–Meiersurvivalanalysisdemonstratedmediansurvivaltimeof9monthsforinitialSLTand12monthsforrepeatSLTwhenusingadefinitionofsuccessas≥20%reductioninIOPfrombaseline.InaseparatestudyofnewlydiagnosedPOAGpatients,repeatSLThadasimilarmeanIOPreductionandtreatmentsuccessrate(IOPreduction≥20%)comparedtoprimarySLTin42eyes[77].Meandurationofsuccessinrepeattreatment(13.1months)waslongerthaninitialtreatment(6.9months).Thisdifferencewasnotstatisticallysignificant.RepeatSLTcanbesuccessfulirrespectivepriorSLTsuccess.Khourietal.[78]performedrepeat360°SLTafterinitialSLTin51OAGeyes.EyeswerestratifiedintothosethathadasuccessfulresponsetoinitialSLT(≥20%IOPreductionfrombaseline)vsamodestresponse(<20%IOPreductionfrombaseline).Forty-onepercentofeyesmetthesuccesscriteriaafterprimarySLTand43%afterrepeatSLT.Inthe22eyeswithtreatmentsuccessafterrepeatSLT,theproportionofeyeswithinitialsuccessfulresponse(11eyes)andmodestresponse(11eyes)wasthesame.Inadifferentstudy[79]oflonger-termoutcomesofrepeat360°SLT,29%ofeyesachievedIOPreduction>20%at24monthscomparedto36%ofeyesfollowinginitialtreatment—thiswasnotstatisticallysignificant.Overall,repeatSLTappearstobecomparabletoinitialSLT.ItachievesasimilarabsolutelevelofIOPcontrolbutmeanIOPreductionsfollowingrepeatSLTappeartobesmaller.ThiscouldbeexplainedbyresidualeffectsofinitialSLTnottypicallywearingoffbeforeretreatment.Inaddition,selectionbiasmayapplywithrepeatSLT,wherepatientswhorespondtoinitialSLTareofferedretreatment.LargerprospectivestudiesinvestigatingrepeatSLTarerequiredtoinvestigatethisfurther.SLTinPACGSLTisnotcommonlyperformedinprimaryangle-closureglaucoma(PACG)patients.VisualisationoftheTMwithintheangleisrequired,whichcanbelimitedinthesepatients.Nonetheless,theefficacyofSLTinPAC/PACGpatientswheresomeoftheangleisopenandvisiblefortreatmenthasbeenevaluated.Narayanaswamyetal.[80]performedaprospectiveRCTtoevaluatetheeffectofSLTinPAC/PACGpatientsthathadpreviouslyundergonelaseriridotomy.Followingiridotomy,theanglewasopenwithatleast180°visibleposteriorTMongonioscopy,butIOPswerestill>21 mm Hg.Atotalof96eyeswererandomisedtoSLTand99eyestoPGAtherapy.At6months,IOPdecreasedby4.0 mm Hg(95%CI,3.2–4.8)intheSLTgroup(P<0.001)andby4.2 mm Hg(95%CI,3.5–4.9)inthePGAgroup(P<0.001).TherewerenodifferencesbetweengroupsintheabsolutemeanreductionofIOP(4.0vs4.2 mm Hg,P=0.78)orinpercentageIOPreduction(16.9vs18.5%,P=0.52).TheprocedureappearedsafeinPAC/PACGpatientswithonlyonepatientsufferingfromatransientIOPspike.InaretrospectivestudycomparingSLTin59eyeswithPAC/PACGpostPIvs59eyeswithPOAG[81],SLTachievedanaverageIOPreductionof38%frombaselineinthePAC/PACGgroupvs32.7%inthePOAGgroup(P=0.08).TreatmentcriteriainthePAC/PACGgrouprequiredatleast180°ofvisibleTM.Inbothgroups,SLTwasperformedaseitheraprimarytreatmentforuncontrolledIOP,asanadjunctforpatientswithuncontrolledIOPonmaximaltoleratedmedicaltherapyorforthoseintoleranttomedicaltherapy.Averagepostoperativefollowwas10–11months.Inbothgroups,SLTpermittedreductionofglaucomamedication(1.6medicationsinPAC/PACGvs1.5medicationsinPOAG,P=0.40).TherewasnosignificantdifferenceinfrequencyofpostlaserIOPspikebetweengroups.SLTinNTGSLTcanbeofbenefitinNTGpatients.Patientshavelowerpre-treatmentbaselineIOPscomparedtoPOAGpatients,sotheabsoluteIOPreductionisoftenless.Moreover,whenusingcommonlyusedsuccesscriteria(IOPreduction>20%frombaseline),thesuccessratesinNTGpatientsappearlower.Leeetal.[82,83]performedaprospectivestudyof41eyeswithNTGpatientsevaluating360°SLTefficacy.At12months,averageIOPreductionwas14.7%frombaselinelevels.Absolutesuccess(IOPreductionof>20%frombaselinewashoutIOPwithoutadditionofadditionalmedication)was22%at12monthsand11.1%at24months.SLTinpseudoexoliationglaucomaSLTinPXFpatientsdemonstratescomparableIOPloweringtoOAGpatients[84,85].Intheirreview,Kennedyetal.reportedameanIOPreductionforPXFeyesof~31.5%at12monthsand31.4%at18months.Sixty-fourpercentofpatientsmaintained≥20%IOPreductionat18monthsand47%at36months[86].PXFalsodoesnotappeartobeariskfactorforpost-lasercomplicationsincludinginflammation.SLTinpigmentaryglaucomaKouchekietal.[87]assessedtheefficacyof360°SLTinacohortofpatientswithpigmentaryglaucoma(PG),POAG,andPXFG.At~16months,meanIOPreductionwas16.7%inPOAG,16.6%withPEX,and14.5%inthePGgroup.PercentageofIOPreductionwasnotsignificantlydifferentbetweengroups(P=0.696)andnosignificantdifferenceinsuccessrateswerenoted(P=0.597).Interestingly,increasedfrequencyofpost-procedurepain,inflammationandIOPspikeswerenotedinthePGgroup.Ahigherrateoffurtherinterventions,eg,repeatSLTortrabeculectomywasalsoobservedinthePGgroup(26.1%)vstheothertwogroups(POAG16.5%,PXF13.6%,P<0.001).Similarassociationshavebeenfoundpreviouslywhereincreasedpost-laserIOPspikeswerenotedinpatientswithheavilypigmentedTM[88].IncreasedTMpigmentationinPGcouldcausemoreenergyabsorptionfollowingSLTresultinginincreasedpain.ThishasledtosuggestionsthatlowerenergysettingsbeusedinPGpatients.Inadifferentstudyassessingtimetofailurein30PGeyesthathadreceived180°SLT[89],averagetimetofailurewas27.4months.Twoeyesexperiencedapost-laserIOPspikehoweveronly180°ofTMwastreatedinthisstudyandlowerenergywasusedlimitingcomparisonswithotherstudies.SLTinsecondaryglaucomaFewstudieshaveinvestigatedSLTefficacyinsecondaryglaucoma.Rubinetal.[90]reportedtheresultsofsevensecondarysteroid-inducedglaucomaeyesthatunderwentSLTafterintravitrealtriamcinoloneinjectionsformacularoedema(sixeyes)orpostcentralretinalveinocclusion(oneeye).PatientshadelevatedIOPdespitemaximumtoleratedmedicaltherapy(meanpreoperativeIOP38.4 mm Hg±7.3)butfollowingSLT,IOPdecreasedto25.9 mm Hg±8.8at1month(P<0.007),23.9 mm Hg±10.6at3months(P<0.006),and15.7 mm Hg±2.2at6months(P<0.001).FourpatientsrequiredrepeatSLTandtwopatientsfailedafterthe3-monthvisit.Bozkurtetal.[91]investigatedwhetherprophylacticSLTcouldreduceorpreventtheIOPriseoftenseenfollowingintravitrealsteroidinjection.Intheirprospectivestudy,15eyesunderwent360°SLT~8daysbeforeintravitrealtriamcinoloneinjectionfordiabeticmacularoedema.IOPrisefrom1to3monthswasreducedandthiseffectwasmaintainedupto6months.Inastudyof15uveiticeyesthathadreceivedintravitrealsteroidtocontrolinflammation,theefficacyofSLTtoreduceIOPwasevaluated[92].MeanIOPbeforeSLTwas30.57 mm Hgandwasloweredto14.85 mm Hg(51.4%reduction)at1month,13.42 mm Hg(55.7%reduction)at6months,and15.14 mm Hg(50.4%reduction)at12months.Seveneyes(46.7%)achievedsuccesscriteria(IOP<22 mm Hgand/ora20%ormorereductioninIOPfromthepre-SLTIOP)at1-month,6-month,and12-monthfollow-upvisits.OnetreatedeyedevelopedaprolongedIOPspikebuttherewerenootheradverseevents.Zhangetal.[93]evaluatedtheefficacyofSLTin42eyeswithsiliconeoil-inducedsecondaryglaucoma.360°SLTwasperformedandmeanIOPdecreasedfrom23.1±1.9 mm Hgpre-treatmentto18.4±3.7 mm Hgaftertreatment(P<0.05).Meannumberofanti-glaucomamedicationsusedforIOPcontrolalsodecreasedfrom2.17±1.21to1.25±0.89(P<0.05).Overall,SLTappearstohavesomeclinicalefficacyinsecondaryglaucomapatients.Furtherlarge-scalestudiesarerequiredtofullyinvestigatethisfurther.Predictorsofsuccess:SLTSLTisnotsuccessfulinalltreatedeyes.Studieshaveanalysedbaselinepatientfactorsthatmaypredictsuccess,frequentlybyperformingunivariateandmultivariateregressionanalysestoseekassociations.Predictorsofsuccesscomparisonsbetweenstudiesisdifficultasmultiplevariationsexistwithinstudies,includingstudysize,patientdemographics,glaucomasubtypetreated,SLTparameters,follow-uplength,anddefinitionof‘success’itself.Thiscreatesdifficultyinestablishing‘definite’robustpredictorsofSLTsuccesswhichisreflectedintheliterature,wheremultiplestudieshavevaryingresults.Themostconsistentlyreportedpatientfactor,whichpredictsSLTsuccessiselevatedbaselineIOP[86].Thisispartlyexplainedbythecommonlyuseddefinitionofsuccess(IOPreduction≥20%frombaseline)tendingtofavourelevatedbaselineIOPs,asthemagnitudeofIOPreductionposttreatmentisoftengreaterwithhigherIOPs.ThisisreflectedinNTGstudieswherebaselineIOPsarelowerandbothabsoluteIOPreductionsandsuccessratesarealsolowercomparedtoothersubtypes[82,83].Onerecentstudysuggestedthatpatientswithpre-treatmentbaselineof<14 mm HgmaynotbenefitfromSLTatall[94].AlimitationofsuchsuccesscriteriaisthatthoughtheyareamarkerofIOPreduction,theymaynotreflectreal-worldclinicalpractice.Patientsmayachieve>20%IOPreductionfrombaselinefollowingSLT,butIOPmaystillberelativelyelevatedandtoohightopreventglaucomaprogression.FewstudieshaveusedpragmaticindividualisedtargetIOPsandassessed‘pursuitofcontrol’fordifferenttreatmentstoobtaintargetIOPs[57].Conversely,higherpre-treatmentbaselineIOPsmayinfactbeassociatedwithincreasedtreatmentfailurepostSLT[95].Patientswithhigherpre-treatmentIOPsaremorelikelytoneedrepeatSLTorsurgeryasthemagnitudeofIOPreductiontocontroldiseaseprogressionislargerandunachievablebysingleSLTtreatmentalone.Otherpatientfactorsincludingsex,race,age,glaucomatype,TMpigmentation,lensstatus,andcentralcornealthicknesshavebeeninvestigatedandfoundnottobepredictiveofSLTsuccess[86,94].CornealbiomechanicalmarkerssuchascornealhysteresisandcornealresistancefactormaybeusefulinhelpingtomodeltheIOP-loweringeffectofSLT[96].Investigatingtheeffectofpre-existingtopicalmedicationonSLTsuccess,Wooetal.[65]foundnosignificantdifferenceinsuccessratebasedonnumberofconcurrenttopicalmedications.Incontrast,Leeetal.[97]foundusingmultipletopicalmedicationsparticularlytopicalcarbonicanhydraseinhibitorswasassociatedwithSLTtreatmentsuccess.Bruenetal.[98]foundthatpre-treatmentwithPGAswasassociatedwithadecreasedIOP-loweringresponse.ThisisfeasibleasbothSLTandPGAshavebeenpurportedtoshareacommonmechanismofaction[32].Complications&adverseeventsSLTisasafeprocedure,whichiswell-toleratedwithlowcomplicationrates.ComplicationsassociatedwithSLTareusuallytransientandself-limiting.IOPspikesimmediatelypostlasercanoccur,withreportedrisesof≥5 mm Hgbeingreportedinupto28%ofeyes[86].AnassociationbetweenIOPspikeshasbeennotedinpatientswithPGandheavilypigmentedTMs[87].AnteriorchamberinflammationisalsocommonpostSLTwithupto83%ofeyesdemonstratingsomedegreeofinflammation[99].ConsideringthebiologicalchangesthatSLTinduces,includingreleaseofpro-inflammatorycytokines,someregardacuteanterioruveitisasapredictableconsequenceoftreatment.Thisinflammationisusuallytransient.UnlikeALT,thedevelopmentofPASisuncommonpostSLT.Intheirmeta-analysis,Wongetal.[45]notedonly2.86%ofcasesdevelopedPASwithincreasedoccurrenceafterrepeatSLT[100].RetinalchangespostSLTarealsorare,butthosedescribedincludecystoidmacularoedema(ofteninpatientswithpredisposingconditions),developmentofsubretinalfluid,andchoroidaleffusions[99].TransientcornealendothelialchangesarewelldescribedpostSLT.Thesecanoccuracutely,withinanhouroftreatmentandaremostlyself-limitingwithnolastingchangestovisualacuity,centralcornealthickness,orendothelialcellcount[101].Afewcasereportsoftransientcornealoedemaandhazehavebeenreportedwithandwithoutresidualcornealstromalscarringandhyperopicshift[102,103,104].Cost-effectivenessofSLTThetreatmentofOAG/OHTimposessignificantcostsonhealth-caresystems.ThetotalannualcostinAustraliafor2005was$1.9billion,ofwhich$355millionwashealthsystemcosts[105].Directandindirectcostsarehigherforseverediseasestates(US$623formildPOAGtoUS$2511forseverePOAG)suggestingearlyeffectiveIOPcontrolcouldreducefuturecosts[106].IntheUSA,Cantoretal.[107]comparedcostsofmedicallyuncontrolledglaucomatreatedwitheitherfurthermedicationsvsSLTorsurgeryifrequired.UsingMarkovmodellingandcostassumptionsbasedonMedicarefeeschedules,theyfound5-yearcumulativecostsperpatientwere$6571,$4838,and$6363inthemedication,SLT,andsurgeryarms,respectively.AnAustralianstudymodelledthecostbenefitoflasertrabeculoplastyasprimarytreatmentcomparedtoconventionalmedicaltreatmentandfoundasavingof$2.50forevery$1spentonlasertreatment,comparedtoinitialmedicaltherapy[105,108].Furthermore,costsavingswereprojectedtocontinueincreasingovertimesincewithanageingpopulation,theprevalence,burden,andtreatmentneededforPOAGwerealsogoingtoincrease[105].Seideretal.[109]calculatedthetimethresholdatwhichbilateralSLTwouldbecomelesscostlythanbilateraluseoftopicalmedicationbydividingtotalcostsofSLTbymonthlycostsofeachmedication.TheyfoundSLTbecamelesscostlythanmostbrand-namemedicationswithin1yearandlesscostlythangenericlatanoprostandgenerictimololafter13and40months,respectively.ThisissupportedbyLeeandHutnik[110]whocomparedprojected6-yearcostsofprimarySLTvsprimarymedicaltherapyinOAGtreatmentinaCanadianhealth-caremodel.IfprimarySLThadtorepeatedbetween2and3years,useofprimarySLTovermono-,bi-,andtri-drugtherapyproduceda6-yearcumulativecost-savingbetween$580.52,$2042.54,and$3366.65dollarsperpatient,respectively.Guedesetal.[111]confirmedthisusingmodellingtoshowprimarySLTdemonstratedbettercost-effectivenessthantopicaltreatmentinthemanagementofbothmildandmoderateglaucomadiseasestates.Inaseparateanalysiscomparing5-yearcostsofinitiatingOAGpatientsonthreedifferenttreatmentarms—initialmedication,initialSLT,orinsertionof×2MIGS(iStent)devices[112],theprojectedaveragecumulativecostat5yearswaslowerintheSLTarm($4730)vsmedicationsarm($6217).TheiStentarmwasprojectedtobecheapest($4420)despitehighestinitialyearzerocosts.Cost-effectivenessstudiesofSLThaveyettobeperformedintheUK.Alarge,UK-basedNIHR-HTAcost-effectivenessstudy(the'LiGHT'Trial)willreportitsfindingsfrom718patientsin2018andwilldeterminewhetherSLTwouldbesimilarlyefficaciousandcost-effectiveinanNHSsetting.QualityoflifeandSLTThepotentialbenefitsofSLTareclear.Itisaprovenalternativetomedicationwithcomparableclinicalefficacy,avoidingmedication-relatedsideeffectsandcomplianceissues.Despitethis,thereislittleevidencetoevaluatewhetherthesebenefitsmanifestasadifferenceinqualityoflife.InaRCTof41medicallycontrolledPOAGpatientsrandomlyallocatedtoreceiveeitheradditional360°SLT(n=22)orcontinuewiththeirusualtreatment(n=19),quality-of-lifeoutcomesweremeasuredatbaselineand6monthsusingtheGlaucomaQualityofLife-15(GQL-15)andComparisonofOphthalmicMedicationsforTolerability(COMTOL)surveyscores.Nostatisticallysignificantdifferenceinthe6-monthGQL-15orCOMTOLscoreascomparedtobaseline(P≥0.4)orbetweenthetwotreatmentgroups(P≥0.2)werenoteddespitegreaterIOPreductionandreductioninnumberofmedicationsintheSLTgroup.ThisisdifferenttoDeKeyseretal.[113]whousedadifferentvalidatedassessmenttoolforqualityoflife—the‘TreatmentSatisfactionSurveyforIntraocularPressure’andfoundsignificantimprovementinparameters,includingsideeffects,eyeappearance,convenienceofuse,andeaseofadministrationat12monthscomparedtotopicaltreatment.Furtherlarge-scalestudiesareneededtoevaluatewhetherSLThasabetterqualityoflifecomparedtotopicaltreatments.FutureNewerlasertrabeculoplastyproceduresareemergingandcurrentlyunderinvestigation.PilotstudieshavecomparedtheirefficacyagainstconventionalSLTthoughfurtherlarge-scaleresearchisrequiredtoestablishwhetheranyofthesenewermodalitiescouldsupersedeSLTinthefuture.MicropulsediodelasertrabeculoplastyDiodelasertrabeculoplasty(DLT)wasfirstdemonstratedtobeeffectiveatIOPloweringintheearly1990s[114]butwasnotedtocausesimilarcoagulativedamageasALT[115].MicropulseDLT(MDLT)wasfirstdescribedbyIngvoldstadetal.[116]Thistechniqueusestrabeculoplastywithsubvisible(subthreshold)applicationsofrepetitiveshortdiode(532,577,or810 nm)laserpulsesspacedbyalongrelaxationtimewithspotsizeof300 μm.MDLTdoesnotcausecoagulativedamagetotheTM[117]andthereisnoblanchingorbubbleformationovertheTMduringthetreatment.Post-treatmentinflammationisminimalhencenoanti-inflammatorymedicationsarerequired.MDLTresultsarevariable—somestudiesreportlimitedIOPloweringsuccess[118]whilstothersreportbetterresultswithmeanIOPreductionbetween19.5-22%withagoodsafetyprofile[119,120].InacomparisonwithALT,thepercentageofeyeswithIOPreduction>20%frombaselinewaslowerwithMDLTcomparedwithALT[121].NolargestudiesexistcomparingitsusewithSLT.Titaniumsapphirelasertrabeculoplasty(TLT)Titaniumsapphirelasertrabeculoplasty(TLT)usesnear-infraredenergy(790 nm)inshortpulses(5–10 μs)withaspotsizeof200 μm.Thenear-infraredwavelengthisbelievedtopenetratedeeper(~200 μm)totheinnerandouterwallsofSchlemm’scanalaswellasthecollectorchannelsandciliarybody.Thelaserisbelievedtobeselectivelyabsorbedbypigmentedphagocyticcells,preservingtheTMtissue[122].ThetotalradiationenergyofTLTis~250timesthatofSLTbutisdeliveredoveralongertimeperiod,resultinginalongerthermalrelaxationtime,causingminimalcollateralcoagulativedamageasaresult[123].InasmallRCTcomparingTLTvsSLTinOAG/OHTpatients,18patientsreceived360°TLTvs19patientsreceived360°SLT.At12months,meanIOPreductionwas22%frombaselineinTLTgroupand20%inSLTgroup.At2years,meanIOPreductionwas35%inTLTgroupand25%frombaseline.NostatisticallysignificantdifferencesinIOPorsuccessrateswerenotedbetweengroups.Treatmentshadasimilaradverseeventsprofilebutdespitethis,someconcernsremainaboutthelongburndurationanddeeperpenetrationofTLTcomparedtoSLT[123].PatternscanninglasertrabeculoplastyThePASCALphotocoagulator(OptiMedicaInc.,SantaClara,CA,USA)wasintroducedin2006forsemi-automatedphotocoagulationoftheretina[124].Thistechnologyusesshortpulsedurations(10–20 ms),100 μmspotsize,andcomputer-guidedpredeterminedpatternofspots.ThisresultsinreductionofthermaldiffusionandsurroundingtissuedamagewhilstpermittingmanymoreshotstobeappliedperareaofTM[117].InarecentRCT[125],thesafety,tolerability,andIOP-loweringefficacyofpatternscanninglasertrabeculoplasty(PSLT)werecomparedagainstSLT.Inall,29OAGpatientsunderwentPSLTinoneeyeandSLTinthefelloweye.TherewasnosignificantdifferenceinmeanIOPreductionatlatestfollow-up(6months).Trans-scleralSLTwithoutgonioscopylensTrans-scleralordirectSLTallows360°treatmentaroundtheperilimbalscleraoverlyingtheTMwithoutagonioscopylens.Thiseliminatescornealandgonioscopy-relatedsideeffects[126,127].ItutilisessimilarlasersettingstoconventionalSLTandhassimilarIOP-loweringefficacybutshotsarefiredsimultaneouslyin<1 sreducingprocedureduration.DirectSLTcouldpotentiallyenabletreatmenttolowerIOPinangleclosure/angle-closureglaucomapatientsasvisibleaccesstotheTMisnotrequiredusingthistechnique.Ifsuccessful,directSLTcouldbewidelyimplemented,includinginthedevelopingworld.Furtherlarger-scalestudiesareunderwaytoevaluatedirectSLT—theGLAUrioustrialisaprospectivemulticentreRCTcomparingSLTvsdirectSLT.Aseparatetrialevaluatingits’useiscurrentlyrecruitinginIsrael.ConclusionsSLTisaseffectiveasALTandtopicalmedicationinPOAG/OHTpatientsbuteasiertodeliver.Itcanbeusedasprimaryoradjuncttreatmentandhaseffectinotherglaucomasubtypes.IthasbeenshowntoreduceIOPfluctuationbutitseffectdoessubsideovertime.SLTisrepeatable,asitcausesminimaldamagetotheTM,andIOPloweringispresentevenifinitialresponsewithprimarySLTislimited.Adverseeventsareuncommonbutmostofthesearetransientandself-limiting.SLThasbeenshowntobeacost-effectiveoptionforprimarytreatmentofglaucomapatientsandevidenceexiststoshowitisassociatedwithbetterqualityoflife.NewertechnologiesareemergingtofurtherdevelopSLTbuttheserequirefurtherinvestigationwithlarger-scalestudies.MethodologyWeusedthefollowingdatabasesandsearchtermstoresearchthisreview:MEDLINE/PubMed:‘SelectiveLaserTrabeculoplasty;‘SLT;‘LaserTrabeculoplasty;Originalresearchstudies;Non-Englishpapersexcluded. Changehistory23October2019Anamendmenttothispaperhasbeenpublishedandcanbeaccessedviaalinkatthetopofthepaper.ReferencesQuigleyHA,BromanAT.Thenumberofpeoplewithglaucomaworldwidein2010and2020.BrJOphthalmol2006;90:262–267.CAS  Article  GoogleScholar  CoakesR.Lasertrabeculoplasty.BrJOphthalmol1992;76:624–626.Article  CAS  PubMed  PubMedCentral  GoogleScholar  WiseJB,WitterSL.Argonlasertherapyforopen-angleglaucoma.Apilotstudy.ArchOphthalmol1979;97:319–322.Article  CAS  PubMed  GoogleScholar  AndersonRR,ParrishJA.Selectivephotothermolysis:precisemicrosurgerybyselectiveabsorptionofpulsedradiation.Science1983;220:524–527.Article  CAS  GoogleScholar  KaganDB,GorfinkelNS,HutnikCM.Mechanismsofselectivelasertrabeculoplasty:areview.ClinExpOphthalmol2014;42:675–681.Article  PubMed  GoogleScholar  ThomasJV,SimmonsRJ,BelcherCD3rd.Argonlasertrabeculoplastyinthepresurgicalglaucomapatient.Ophthalmology1982;89:187–197.Article  CAS  PubMed  GoogleScholar  BrubakerRF,LiesegangTJ.Effectoftrabecularphotocoagulationontheaqueoushumordynamicsofthehumaneye.AmJOphthalmol1983;96:139–147.Article  CAS  PubMed  GoogleScholar  RodriguesMM,SpaethGL,DonohooP.Electronmicroscopyofargonlasertherapyinphakicopen-angleglaucoma.Ophthalmology1982;89:198–210.Article  CAS  PubMed  GoogleScholar  BradleyJM,AnderssohnAM,ColvisCM,ParshleyDE,ZhuXH,RuddatMSetal.Mediationoflasertrabeculoplasty-inducedmatrixmetalloproteinaseexpressionbyIL-1betaandTNFalpha.InvestOphthalmolVisSci2000;41:422–430.CAS  PubMed  GoogleScholar  TheGlaucomaLaserTrial(GLT).2.Resultsofargonlasertrabeculoplastyversustopicalmedicines.TheGlaucomaLaserTrialResearchGroup.Ophthalmology1990;97:1403–1413.Article  GoogleScholar  SchwartzAL,LoveDC,SchwartzMA.Long-termfollow-upofargonlasertrabeculoplastyforuncontrolledopen-angleglaucoma.ArchOphthalmol1985;103:1482–1484.Article  CAS  PubMed  GoogleScholar  BaezKA,SpaethGL.Argonlasertrabeculoplastycontrolsonethirdofpatientswithprogressive,uncontrolledopen-angleglaucomaforfiveyears.TransAmOphthalmolSoc1991;89:47–56;discussion-8.CAS  PubMed  PubMedCentral  GoogleScholar  GrinichNP,VanBuskirkEM,SamplesJR.Three-yearefficacyofargonlasertrabeculoplasty.Ophthalmology1987;94:858–861.Article  CAS  PubMed  GoogleScholar  RichterCU,ShingletonBJ,BellowsAR,HutchinsonBT,JacobsonLP.Retreatmentwithargonlasertrabeculoplasty.Ophthalmology1987;94:1085–1089.Article  CAS  PubMed  GoogleScholar  HigginbothamEJ,RichardsonTM.Responseofexfoliationglaucomatolasertrabeculoplasty.BrJOphthalmol1986;70:837–839.Article  CAS  PubMed  PubMedCentral  GoogleScholar  TheGlaucomaLaserTrial.I.Acuteeffectsofargonlasertrabeculoplastyonintraocularpressure.GlaucomaLaserTrialResearchGroup.ArchOphthalmol1989;107:1135–1142.Article  GoogleScholar  KeightleySJ,KhawPT,ElkingtonAR.Thepredictionofintraocularpressurerisefollowingargonlasertrabeculoplasty.Eye(Lond)1987;1(Pt5):577–580.Article  GoogleScholar  RouhiainenHJ,TerasvirtaME,TuovinenEJ.Peripheralanteriorsynechiaeformationaftertrabeculoplasty.ArchOphthalmol1988;106:189–191.Article  CAS  PubMed  GoogleScholar  RichterCU,ShingletonBJ,BellowsAR,HutchinsonBT,O'ConnorT,BrillI.Thedevelopmentofencapsulatedfilteringblebs.Ophthalmology1988;95:1163–1168.Article  CAS  PubMed  GoogleScholar  MigdalC,HitchingsR.Controlofchronicsimpleglaucomawithprimarymedical,surgicalandlasertreatment.TransOphthalmolSocUK1986;105:653–656.PubMed  GoogleScholar  LatinaMA,ParkC.Selectivetargetingoftrabecularmeshworkcells:invitrostudiesofpulsedandCWlaserinteractions.ExpEyeRes1995;60:359–371.Article  CAS  PubMed  GoogleScholar  AroraKS,RobinAL,CorcoranKJ,CorcoranSL,RamuluPY.Useofvariousglaucomasurgeriesandproceduresinmedicarebeneficiariesfrom1994to2012.Ophthalmology2015;122:1615–1624.Article  GoogleScholar  GulatiV,FanS,GardnerBJ,HavensSJ,SchaafMT,NeelyDGetal.Mechanismofactionofselectivelasertrabeculoplastyandpredictorsofresponse.InvestOphthalmolVisSci2017;58:1462–1468.Article  PubMed  PubMedCentral  GoogleScholar  GoyalS,Beltran-AgulloL,RashidS,ShahSP,NathR,ObiAetal.Effectofprimaryselectivelasertrabeculoplastyontonographicoutflowfacility:arandomisedclinicaltrial.BrJOphthalmol2010;94(11):1443–1447.Article  PubMed  GoogleScholar  KramerTR,NoeckerRJ.Comparisonofthemorphologicchangesafterselectivelasertrabeculoplastyandargonlasertrabeculoplastyinhumaneyebankeyes.Ophthalmology2001;108:773–779.Article  CAS  PubMed  GoogleScholar  SooHooJR,SeiboldLK,AmmarDA,KahookMY.Ultrastructuralchangesinhumantrabecularmeshworktissueafterlasertrabeculoplasty.JOphthalmol2015;2015:476138.PubMed  PubMedCentral  GoogleScholar  IzzottiA,LongobardiM,CartigliaC,RathschulerF,SaccaSC.Trabecularmeshworkgeneexpressionafterselectivelasertrabeculoplasty.PLoSONE2011;6:e20110.Article  CAS  PubMed  PubMedCentral  GoogleScholar  LeeJY,KaganDB,RoumeliotisG,LiuH,HutnikCM.Secretionofmatrixmetalloproteinase-3byco-culturedpigmentedandnon-pigmentedhumantrabecularmeshworkcellsfollowingselectivelasertrabeculoplasty.ClinExpOphthalmol2016;44:33–42.Article  PubMed  GoogleScholar  AlvaradoJA,KatzLJ,TrivediS,ShiferaAS.Monocytemodulationofaqueousoutflowandrecruitmenttothetrabecularmeshworkfollowingselectivelasertrabeculoplasty.ArchOphthalmol2010;128:731–737.Article  PubMed  GoogleScholar  GuzeyM,VuralH,SaticiA.Endothelin-1increaseinaqueoushumourcausedbyfrequency-doubledNd:YAGlasertrabeculoplastyinrabbits.Eye(Lond)2001;15:781–785.Article  CAS  GoogleScholar  GuzeyM,VuralH,SaticiA,KaradedeS,DoganZ.IncreaseoffreeoxygenradicalsinaqueoushumourinducedbyselectiveNd:YAGlasertrabeculoplastyintherabbit.EurJOphthalmol2001;11:47–52.Article  CAS  PubMed  GoogleScholar  AlvaradoJA,IguchiR,MartinezJ,TrivediS,ShiferaAS.SimilareffectsofselectivelasertrabeculoplastyandprostaglandinanalogsonthepermeabilityofculturedSchlemmcanalcells.AmJOphthalmol2010;150:254–264.Article  CAS  PubMed  GoogleScholar  ChenE,GolchinS,BlomdahlS.Acomparisonbetween90degreesand180degreesselectivelasertrabeculoplasty.JGlaucoma2004;13:62–65.Article  PubMed  GoogleScholar  NagarM,OgunyomadeA,O'BrartDP,HowesF,MarshallJ.Arandomised,prospectivestudycomparingselectivelasertrabeculoplastywithlatanoprostforthecontrolofintraocularpressureinocularhypertensionandopenangleglaucoma.BrJOphthalmol2005;89:1413–1417.Article  CAS  PubMed  PubMedCentral  GoogleScholar  TangM,FuY,FuMS,FanY,ZouHD,SunXDetal.Theefficacyoflow-energyselectivelasertrabeculoplasty.OphthalmicSurgLasersImaging2011;42:59–63.Article  PubMed  GoogleScholar  LeeJW,WongMO,LiuCC,LaiJS.Optimalselectivelasertrabeculoplastyenergyformaximalintraocularpressurereductioninopen-angleglaucoma.JGlaucoma2015;24:e128–e131.Article  PubMed  GoogleScholar  StunfPuklS,Drnovšek-OlupB.Impactoflaserpulsedurationonthereductionofintraocularpressureduringselectivelasertrabeculoplasty.IntOphthalmol2016.Availableat:https//doi.org/10.1007/s10792-016-0426-x.ZhangL,WeizerJS,MuschDC.Perioperativemedicationsforpreventingtemporarilyincreasedintraocularpressureafterlasertrabeculoplasty.CochraneDatabaseSystRev2017;2:Cd010746.PubMed  GoogleScholar  DeKeyserM,DeBelderM,DeGrootV.Randomizedprospectivestudyoftheuseofanti-inflammatorydropsafterselectivelasertrabeculoplasty.JGlaucoma2017;26:e22–e29.PubMed  GoogleScholar  RealiniT,CharltonJ,HettlingerM.Theimpactofanti-inflammatorytherapyonintraocularpressurereductionfollowingselectivelasertrabeculoplasty.OphthalmicSurgLasersImaging2010;41:100–103.Article  PubMed  GoogleScholar  JinapriyaD,D'SouzaM,HollandsH,El-DefrawySR,IrrcherI,SmallmanDetal.Anti-inflammatorytherapyafterselectivelasertrabeculoplasty:arandomized,double-masked,placebo-controlledclinicaltrial.Ophthalmology2014;121:2356–2361.Article  PubMed  GoogleScholar  LatinaMA,SibayanSA,ShinDH,NoeckerRJ,MarcellinoG.Q-switched532-nmNd:YAGlasertrabeculoplasty(selectivelasertrabeculoplasty):amulticenter,pilot,clinicalstudy.Ophthalmology.1998;105:2082–2088;discussion9-90.LeahyKE,WhiteAJ.Selectivelasertrabeculoplasty:currentperspectives.ClinOphthalmol2015;9:833–841.PubMed  PubMedCentral  GoogleScholar  McAlindenC.Selectivelasertrabeculoplasty(SLT)vsothertreatmentmodalitiesforglaucoma:systematicreview.Eye(Lond)2014;28:249–258.Article  CAS  GoogleScholar  WongMO,LeeJW,ChoyBN,ChanJC,LaiJS.Systematicreviewandmeta-analysisontheefficacyofselectivelasertrabeculoplastyinopen-angleglaucoma.SurvOphthalmol2015;60:36–50.Article  PubMed  GoogleScholar  LiuY,BirtCM.Argonversusselectivelasertrabeculoplastyinyoungerpatients:2-yearresults.JGlaucoma2012;21:112–115.PubMed  GoogleScholar  BovellAM,DamjiKF,HodgeWG,RockWJ,BuhrmannRR,PanYI.Longtermeffectsontheloweringofintraocularpressure:selectivelaserorargonlasertrabeculoplasty?CanJOphthalmol2011;46:408–413.Article  PubMed  GoogleScholar  RosenfeldE,ShemeshG,KurtzS.Theefficacyofselectivelasertrabeculoplastyversusargonlasertrabeculoplastyinpseudophakicglaucomapatients.ClinOphthalmol2012;6:1935–1940.Article  PubMed  PubMedCentral  GoogleScholar  KentSS,HutnikCM,BirtCM,DamjiKF,HarasymowyczP,SiFetal.Arandomizedclinicaltrialofselectivelasertrabeculoplastyversusargonlasertrabeculoplastyinpatientswithpseudoexfoliation.JGlaucoma2015;24:344–347.Article  PubMed  GoogleScholar  WangW,HeM,ZhouM,ZhangX.Selectivelasertrabeculoplastyversusargonlasertrabeculoplastyinpatientswithopen-angleglaucoma:asystematicreviewandmeta-analysis.PLoSOne2013;8:e84270.Article  CAS  PubMed  PubMedCentral  GoogleScholar  RolimdeMouraC,ParanhosAJr,WormaldR.Lasertrabeculoplastyforopenangleglaucoma.CochraneDatabaseSystRev2007;Cd003919.WangH,ChengJW,WeiRL,CaiJP,LiY,MaXY.Meta-analysisofselectivelasertrabeculoplastywithargonlasertrabeculoplastyinthetreatmentofopen-angleglaucoma.CanJOphthalmol2013;48:186–192.Article  PubMed  GoogleScholar  NagarM,LuhishiE,ShahN.Intraocularpressurecontrolandfluctuation:theeffectoftreatmentwithselectivelasertrabeculoplasty.BrJOphthalmol2009;93:497–501.Article  CAS  PubMed  GoogleScholar  LiX,WangW,ZhangX.Meta-analysisofselectivelasertrabeculoplastyversustopicalmedicationinthetreatmentofopen-angleglaucoma.BMCOphthalmol2015;5:107.Article  CAS  PubMed  PubMedCentral  GoogleScholar  McIlraithI,StrasfeldM,ColevG,HutnikCM.Selectivelasertrabeculoplastyasinitialandadjunctivetreatmentforopen-angleglaucoma.JGlaucoma2006;15:124–130.Article  PubMed  GoogleScholar  LaiJS,ChuaJK,ThamCC,LamDS.Five-yearfollowupofselectivelasertrabeculoplastyinChineseeyes.ClinExpOphthalmol2004;32:368–372.Article  PubMed  GoogleScholar  KatzLJ,SteinmannWC,KabirA,MolineauxJ,WizovSS,MarcellinoG.Selectivelasertrabeculoplastyversusmedicaltherapyasinitialtreatmentofglaucoma:aprospective,randomizedtrial.JGlaucoma2012;21:460–468.Article  PubMed  GoogleScholar  TheAdvancedGlaucomaInterventionStudy(AGIS):11.Riskfactorsforfailureoftrabeculectomyandargonlasertrabeculoplasty.AmJOphthalmol2002;134:481–498.FeaAM,AhmedII,LaviaC,MitticaP,ConsolandiG,MotoleseIetal.Hydrusmicrostentcomparedtoselectivelasertrabeculoplastyinprimaryopenangleglaucoma:oneyearresults.ClinExpOphthalmol2017;45:120–127.Article  PubMed  GoogleScholar  WeinandFS,AlthenF.Long-termclinicalresultsofselectivelasertrabeculoplastyinthetreatmentofprimaryopenangleglaucoma.EurJOphthalmol2006;16:100–104.Article  CAS  PubMed  GoogleScholar  LeeJW,ChanCW,WongMO,ChanJ,LiQ,LaiJS.Arandomizedcontroltrialtoevaluatetheeffectofadjuvantselectivelasertrabeculoplastyversusmedicationaloneinprimaryopen-angleglaucoma:preliminaryresults.ClinOphthalmol2014;8:1987–1992.Article  PubMed  PubMedCentral  GoogleScholar  PatelV,ElHawyE,WaisbourdM,ZangalliC,ShapiroDM,GuptaLetal.Long-termoutcomesinpatientsinitiallyresponsivetoselectivelasertrabeculoplasty.IntJOphthalmol2015;8:960–964.PubMed  PubMedCentral  GoogleScholar  CvenkelB.One-yearfollow-upofselectivelasertrabeculoplastyinopen-angleglaucoma.Ophthalmologica2004;218:20–25.Article  PubMed  GoogleScholar  FrancisBA,IanchulevT,SchofieldJK,MincklerDS.Selectivelasertrabeculoplastyasareplacementformedicaltherapyinopen-angleglaucoma.AmJOphthalmol2005;140:524–525.Article  PubMed  GoogleScholar  WooDM,HealeyPR,GrahamSL,GoldbergI.Intraocularpressure-loweringmedicationsandlong-termoutcomesofselectivelasertrabeculoplasty.ClinExpOphthalmol2015;43:320–327.Article  PubMed  GoogleScholar  BirtCM.Selectivelasertrabeculoplastyretreatmentafterpriorargonlasertrabeculoplasty:1-yearresults.CanJOphthalmol2007;42:715–719.Article  PubMed  GoogleScholar  ZhangH,YangY,XuJ,YuM.Selectivelasertrabeculoplastyintreatingpost-trabeculectomyadvancedprimaryopen-angleglaucoma.ExpTherMed2016;11:1090–1094.Article  CAS  PubMed  GoogleScholar  AsraniS,ZeimerR,WilenskyJ,GieserD,VitaleS,LindenmuthK.Largediurnalfluctuationsinintraocularpressureareanindependentriskfactorinpatientswithglaucoma.JGlaucoma2000;9:134–142.Article  CAS  PubMed  GoogleScholar  KiddeeW,AtthavuttisilpS.Theeffectsofselectivelasertrabeculoplastyandtravoprostoncircadianintraocularpressurefluctuations:arandomizedclinicaltrial.Medicine2017;96):e6047.Article  CAS  PubMed  PubMedCentral  GoogleScholar  PrasadN,MurthyS,DagianisJJ,LatinaMA.Acomparisonoftheintervisitintraocularpressurefluctuationafter180and360degreesofselectivelasertrabeculoplasty(SLT)asaprimarytherapyinprimaryopenangleglaucomaandocularhypertension.JGlaucoma2009;18:157–160.Article  PubMed  GoogleScholar  LeeJW,FuL,ChanJC,LaiJS.Twenty-four-hourintraocularpressurerelatedchangesfollowingadjuvantselectivelasertrabeculoplastyfornormaltensionglaucoma.Medicine2014;93:e238.Article  PubMed  PubMedCentral  GoogleScholar  TojoN,OkaM,MiyakoshiA,OzakiH,HayashiA.Comparisonoffluctuationsofintraocularpressurebeforeandafterselectivelasertrabeculoplastyinnormal-tensionglaucomapatients.JGlaucoma2014;23:e138–e143.Article  PubMed  GoogleScholar  AyalaM.Intraocularpressurereductionafterinitialfailureofselectivelasertrabeculoplasty(SLT).GraefesArchClinExpOphthalmol2014;252:315–320.Article  PubMed  GoogleScholar  FrancisBA,LoewenN,HongB,DustinL,KaplowitzK,KinastRetal.Repeatabilityofselectivelasertrabeculoplastyforopen-angleglaucoma.BMCOphthalmol2016;16:128.Article  CAS  PubMed  PubMedCentral  GoogleScholar  HongBK,WinerJC,MartoneJF,WandM,AltmanB,ShieldsB.Repeatselectivelasertrabeculoplasty.JGlaucoma2009;18:180–183.Article  PubMed  PubMedCentral  GoogleScholar  PolatJ,GranthamL,MitchellK,RealiniT.Repeatabilityofselectivelasertrabeculoplasty.BrJOphthalmol2016;100:1437–1441.Article  PubMed  GoogleScholar  AveryN,AngGS,NicholasS,WellsA.Repeatabilityofprimaryselectivelasertrabeculoplastyinpatientswithprimaryopen-angleglaucoma.IntOphthalmol2013;33:501–506.Article  PubMed  GoogleScholar  KhouriAS,LinJ,BerezinaTL,MaltzmanB,FechtnerRD.Repeatselectivelasertrabeculoplastycanbeeffectiveineyeswithinitialmodestresponse.MiddleEastAfrJOphthalmol2014;21:205–209.Article  PubMed  PubMedCentral  GoogleScholar  KhouriAS,LariHB,BerezinaTL,MaltzmanB,FechtnerRD.Longtermefficacyofrepeatselectivelasertrabeculoplasty.JOphthalmicVisRes2014;9:444–448.Article  PubMed  PubMedCentral  GoogleScholar  NarayanaswamyA,LeungCK,IstiantoroDV,PereraSA,HoCL,NongpiurMEetal.Efficacyofselectivelasertrabeculoplastyinprimaryangle-closureglaucoma:arandomizedclinicaltrial.JAMAOphthalmol2015;133:206–212.Article  PubMed  GoogleScholar  AliAljasimL,OwaidhahO,EdwardDP.Selectivelasertrabeculoplastyinprimaryangle-closureglaucomaafterlaserperipheraliridotomy:acase-controlstudy.JGlaucoma2016;25:e253–e258.Article  PubMed  GoogleScholar  LeeJW,HoWL,ChanJC,LaiJS.Efficacyofselectivelasertrabeculoplastyfornormaltensionglaucoma:1yearresults.BMCOphthalmol2015;15:1.Article  PubMed  PubMedCentral  GoogleScholar  LeeJW,ShumJJ,ChanJC,LaiJS.Two-yearclinicalresultsafterselectivelasertrabeculoplastyfornormaltensionglaucoma.Medicine2015;94:e984.Article  PubMed  PubMedCentral  GoogleScholar  ShazlyTA,SmithJ,LatinaMA.Long-termsafetyandefficacyofselectivelasertrabeculoplastyasprimarytherapyforthetreatmentofpseudoexfoliationglaucomacomparedwithprimaryopen-angleglaucoma.ClinOphthalmol2010;5:5–10.Article  PubMed  PubMedCentral  GoogleScholar  AyalaM,ChenE.Comparisonofselectivelasertrabeculoplasty(SLT)inprimaryopenangleglaucomaandpseudoexfoliationglaucoma.ClinOphthalmol2011;5:1469–1473.Article  PubMed  PubMedCentral  GoogleScholar  KennedyJB,SooHooJR,KahookMY,SeiboldLK.Selectivelasertrabeculoplasty:anupdate.AsiaPacJOphthalmol2016;5:63–69.Article  GoogleScholar  KouchekiB,HashemiH.Selectivelasertrabeculoplastyinthetreatmentofopen-angleglaucoma.JGlaucoma2012;21:65–70.Article  PubMed  GoogleScholar  HarasymowyczPJ,PapamatheakisDG,LatinaM,DeLeonM,LeskMR,DamjiKF.Selectivelasertrabeculoplasty(SLT)complicatedbyintraocularpressureelevationineyeswithheavilypigmentedtrabecularmeshworks.AmJOphthalmol2005;139:1110–1113.Article  PubMed  GoogleScholar  AyalaM.Long-termoutcomesofselectivelasertrabeculoplasty(SLT)treatmentinpigmentaryglaucomapatients.JGlaucoma2014;23:616–619.Article  PubMed  GoogleScholar  RubinB,TaglientiA,RothmanRF,MarcusCH,SerleJB.Theeffectofselectivelasertrabeculoplastyonintraocularpressureinpatientswithintravitrealsteroid-inducedelevatedintraocularpressure.JGlaucoma2008;17:287–292.Article  PubMed  GoogleScholar  BozkurtE,KaraN,YaziciAT,YukselK,DemirokA,YilmazOFetal.Prophylacticselectivelasertrabeculoplastyinthepreventionofintraocularpressureelevationafterintravitrealtriamcinoloneacetonideinjection.AmJOphthalmol2011;152:976–981.e2.Article  PubMed  GoogleScholar  MalekiA,SwanRT,LasaveAF,MaL,FosterCS.SelectiveLaserTrabeculoplastyinControlledUveitiswithSteroid-InducedGlaucoma.Ophthalmology2016;123:2630–2632.Article  PubMed  GoogleScholar  ZhangM,LiB,WangJ,LiuW,SunY,WuX.Clinicalresultsofselectivelasertrabeculoplastyinsiliconeoil-inducedsecondaryglaucoma.GraefesArchClinExpOphalmol2014;252:983–987.Article  CAS  GoogleScholar  PillunatKR,SpoerlE,ElfesG,PillunatLE.Preoperativeintraocularpressureasapredictorofselectivelasertrabeculoplastyefficacy.ActaOphthalmol2016;94:692–696.Article  PubMed  GoogleScholar  MikiA,KawashimaR,UsuiS,MatsushitaK,NishidaK.Treatmentoutcomesandprognosticfactorsofselectivelasertrabeculoplastyforopen-angleglaucomareceivingmaximal-tolerablemedicaltherapy.JGlaucoma2016;25:785–789.Article  PubMed  GoogleScholar  HirneissC,SekuraK,BrandlhuberU,KampikA,KerntM.Cornealbiomechanicspredicttheoutcomeofselectivelasertrabeculoplastyinmedicallyuncontrolledglaucoma.GraefesArchClinExpOphthalmol2013;251:2383–2388.Article  PubMed  GoogleScholar  LeeJW,LiuCC,ChanJ,WongRL,WongIY,LaiJS.PredictorsofsuccessinselectivelasertrabeculoplastyforprimaryopenangleglaucomainChinese.ClinOphthalmol2014;8:1787–1791.Article  PubMed  PubMedCentral  GoogleScholar  BruenR,LeskMR,HarasymowyczP.BaselinefactorspredictiveofSLTresponse:aprospectivestudy.JOphthalmol2012;2012:642869.PubMed  PubMedCentral  GoogleScholar  SongJ.Complicationsofselectivelasertrabeculoplasty:areview.ClinOphthalmol2016;10:137–143.Article  CAS  PubMed  PubMedCentral  GoogleScholar  BaserEF,AkbulutD.Significantperipheralanteriorsynechiaeafterrepeatselectivelasertrabeculoplasty.CanJOphthalmol2015;50(3):e36–e38.Article  PubMed  GoogleScholar  OngK,OngL,OngLB.Cornealendothelialabnormalitiesafterselectivelasertrabeculoplasty(SLT).JGlaucoma2015;24:286–290.Article  PubMed  GoogleScholar  MoubayedSP,HamidM,ChoremisJ,LiG.Anunusualfindingofcornealedemacomplicatingselectivelasertrabeculoplasty.CanJOphthalmol2009;44:337–338.Article  PubMed  GoogleScholar  ReginaM,BunyaVY,OrlinSE,AnsariH.Cornealedemaandhazeafterselectivelasertrabeculoplasty.JGlaucoma2011;20:327–329.Article  PubMed  GoogleScholar  KnickelbeinJE,SinghA,FlowersBE,NairUK,EisenbergM,DavisRetal.Acutecornealedemawithsubsequentthinningandhyperopicshiftfollowingselectivelasertrabeculoplasty.JCataractRefractSurg2014;40:1731–1735.Article  PubMed  PubMedCentral  GoogleScholar  DiraniM,CrowstonJG,TaylorPS,MoorePT,RogersS,PezzulloMLetal.Economicimpactofprimaryopen-angleglaucomainAustralia.ClinExpOphthalmol2011;39:623–632.Article  PubMed  GoogleScholar  LeePP,WaltJG,DoyleJJ,KotakSV,EvansSJ,BudenzDLetal.Amulticenter,retrospectivepilotstudyofresourceuseandcostsassociatedwithseverityofdiseaseinglaucoma.ArchOphthalmol2006;124:12–19.Article  PubMed  GoogleScholar  CantorLB,KatzLJ,ChengJW,ChenE,TongKB,PeabodyJW.Economicevaluationofmedication,lasertrabeculoplastyandfilteringsurgeriesintreatingpatientswithglaucomaintheUS.CurrMedResOpin2008;24:2905–2918.Article  PubMed  GoogleScholar  TaylorHR.Glaucoma:wheretonow?Ophthalmology2009;116:821–822.Article  PubMed  GoogleScholar  SeiderMI,KeenanJD,HanY.Costofselectivelasertrabeculoplastyvstopicalmedicationsforglaucoma.ArchOphthalmol2012;130:529–530.Article  PubMed  GoogleScholar  LeeR,HutnikCM.ProjectedcostcomparisonofselectivelasertrabeculoplastyversusglaucomamedicationintheOntarioHealthInsurancePlan.CanJOphthalmol2006;41:449–456.Article  PubMed  GoogleScholar  GuedesRA,GuedesVM,GomesCE,ChaoubahA.Maximizingcost-effectivenessbyadjustingtreatmentstrategyaccordingtoglaucomaseverity.Medicine2016;95:e5745.Article  PubMed  PubMedCentral  GoogleScholar  BerdahlJP,KhatanaAK,KatzLJ,HerndonL,LaytonAJ,YuTMetal.Cost-comparisonoftwotrabecularmicro-bypassstentsversusselectivelasertrabeculoplastyormedicationsonlyforintraocularpressurecontrolforpatientswithopen-angleglaucoma.JMedEcon2017;20:760–766.Article  PubMed  GoogleScholar  DeKeyserM,DeBelderM,DeGrootV.Qualityoflifeinglaucomapatientsafterselectivelasertrabeculoplasty.IntJOphthalmol2017;10:742–748.PubMed  PubMedCentral  GoogleScholar  McHughD,MarshallJ,FfytcheTJ,HamiltonPA,RavenA.Diodelasertrabeculoplasty(DLT)forprimaryopen-angleglaucomaandocularhypertension.BrJOphthalmol1990;74:743–747.Article  CAS  PubMed  PubMedCentral  GoogleScholar  McHughD,MarshallJ,FfytcheTJ,HamiltonPA,RavenA.Ultrastructuralchangesofhumantrabecularmeshworkafterphotocoagulationwithadiodelaser.InvestOphthalmolVisSci1992;33:2664–2671.CAS  PubMed  GoogleScholar  IngvoldstadDD,KrishnaR,WilloughbyL.MicroPulsediodelasertrabeculoplastyversusargonlasertrabeculoplastyinthetreatmentofopenangleglaucoma.InvestOphthalmolVisSci2005;46:123. GoogleScholar  EkiciF,WaisbourdM,KatzLJ.Currentandfutureoflasertherapyinthemanagementofglaucoma.OpenOphthalmolJ2016;10:56–67.Article  PubMed  PubMedCentral  GoogleScholar  RantalaE,ValimakiJ.Micropulsediodelasertrabeculoplasty—180-degreetreatment.ActaOphthalmol2012;90:441–444.Article  PubMed  GoogleScholar  FeaAM,BosoneA,RolleT,BrogliattiB,GrignoloFM.Micropulsediodelasertrabeculoplasty(MDLT):AphaseIIclinicalstudywith12monthsfollow-up.ClinOphthalmol2008;2:247–252.Article  PubMed  PubMedCentral  GoogleScholar  LeeJW,YauGS,YickDW,YuenCY.MicroPulselasertrabeculoplastyforthetreatmentofopen-angleglaucoma.Medicine2015;94:e2075.Article  PubMed  PubMedCentral  GoogleScholar  Detry-MorelM,MuschartF,PourjavanS.Micropulsediodelaser(810nm)versusargonlasertrabeculoplastyinthetreatmentofopen-angleglaucoma:comparativeshort-termsafetyandefficacyprofile.BullSocBelgeOphtalmol2008;308:21–28. GoogleScholar  GoldenfeldM,MelamedS,SimonG,BenSimonGJ.Titanium:sapphirelasertrabeculoplastyversusargonlasertrabeculoplastyinpatientswithopen-angleglaucoma.OphthalmicSurgLasersImaging2009;40:264–269.Article  PubMed  GoogleScholar  KaplowitzK,WangS,BilonickR,OattsJT,GrippoT,LoewenNA.Randomizedcontrolledcomparisonoftitanium-sapphireversusstandardQ-switchedNd:YAGlasertrabeculoplasty.JGlaucoma2016;25:e663–e667.Article  PubMed  GoogleScholar  BlumenkranzMS,YellachichD,AndersenDE,WiltbergerMW,MordauntD,MarcellinoGRetal.Semiautomatedpatternedscanninglaserforretinalphotocoagulation.Retina2006;26:370–376.Article  PubMed  GoogleScholar  MansouriK,ShaarawyT.Comparingpatternscanninglasertrabeculoplastytoselectivelasertrabeculoplasty:arandomizedcontrolledtrial.ActaOphthalmol2017;95:e361–e365.Article  PubMed  GoogleScholar  BelkinM,GeffenN,OfirS,KaplanMessasA,BarkanaY,BelkinAetal.Directtrans-scleralselectivelasertrabeculoplasty(SLT)withoutagonioscopylens.InvestOphthalmolVisSci2014;55:819. GoogleScholar  GeffenN,OfirS,BelkinA,SegevF,BarkanaY,KaplanMessasAetal.Transscleralselectivelasertrabeculoplastywithoutagonioscopylens.JGlaucoma2017;26:201–207.Article  PubMed  GoogleScholar  DownloadreferencesAuthorinformationAuthorsandAffiliationsDepartmentofGlaucoma,MoorfieldsEyeHospital,London,UKA.Garg & G.GazzardAuthorsA.GargViewauthorpublicationsYoucanalsosearchforthisauthorin PubMed GoogleScholarG.GazzardViewauthorpublicationsYoucanalsosearchforthisauthorin PubMed GoogleScholarCorrespondingauthorCorrespondenceto G.Gazzard.Ethicsdeclarations Conflictofinterest Theauthorsdeclarethattheyhavenoconflictofinterest. RightsandpermissionsReprintsandPermissionsAboutthisarticleCitethisarticleGarg,A.,Gazzard,G.Selectivelasertrabeculoplasty:past,present,andfuture. Eye32,863–876(2018).https://doi.org/10.1038/eye.2017.273DownloadcitationReceived:19October2017Accepted:02November2017Published:05January2018IssueDate:May2018DOI:https://doi.org/10.1038/eye.2017.273SharethisarticleAnyoneyousharethefollowinglinkwithwillbeabletoreadthiscontent:GetshareablelinkSorry,ashareablelinkisnotcurrentlyavailableforthisarticle.Copytoclipboard ProvidedbytheSpringerNatureSharedItcontent-sharinginitiative Furtherreading Effectofpigmentationintensityoftrabecularmeshworkcellsonmechanismsofmicropulselasertrabeculoplasty ShotaShimizu MegumiHonjo MakotoAihara ScientificReports(2022) Recenttrendsinglaucomasurgery:anationwidedatabasestudyinJapan,2011–2019 AsahiFujita YoheiHashimoto MakotoAihara JapaneseJournalofOphthalmology(2022) AngleClosureGlaucoma—UpdateonTreatmentParadigms SuneeChansangpetch ShanC.Lin CurrentOphthalmologyReports(2022) Long-termresultsofmicropulselasertrabeculoplastywith577-nmyellowwavelengthinpatientswithuncontrolledprimaryopen-angleglaucomaandpseudoexfoliationglaucoma SevdaAydinKurna AyseDemircilerSonmez AhmetAltun LasersinMedicalScience(2022) CaffeineandItsNeuroprotectiveRoleinIschemicEvents:AMechanismDependentonAdenosineReceptors D.Pereira-Figueiredo A.A.Nascimento K.C.Calaza CellularandMolecularNeurobiology(2022) DownloadPDF AssociatedContent Collection 30thAnniversaryoftheRoyalCollegeofOphthalmologists Advertisement Explorecontent Researcharticles Reviews&Analysis News&Comment Currentissue Collections FollowusonTwitter Signupforalerts RSSfeed Aboutthejournal JournalInformation Openaccesspublishing AbouttheEditors SpecialIssues AboutthePartner EYECovers Contact ForAdvertisers Subscribe Publishwithus ForAuthors&Referees Submitmanuscript Search Searcharticlesbysubject,keywordorauthor Showresultsfrom Alljournals Thisjournal Search Advancedsearch Quicklinks Explorearticlesbysubject Findajob Guidetoauthors Editorialpolicies