LasertrabeculoplastyassupplementarytreatmentforprimaryopenangleglaucomapressureineacheyebymeansofaGoldmannapplanationtonometerwastakenastheaveragepressureofthelastthreeclinicvisitsOneeyewasthenran ID: 958799
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BritishJournalofOphthalmology,1987,71,188-191LasertrabeculoplastyassupplementarytreatmentforprimaryopenangleglaucomaMARKBSHERWOOD,JOHNLATTIMER,ANDROGERAHITCHINGSFromMoorfieldsEyeHospital,HighHolborn,LondonWCIV2ANSUMMARYAprospectivetrialwasconductedoflasertrabeculoplastyrandomlyassignedtooneeyeofagroupofelderlypatientswithbilateralprimaryphakicopenangleglaucomawhowerealreadytakingthemaximummedicaltreatmentthattheycouldtolerate.Withaminimumfollow-upof21/2years(mean35months)asignificantfallinmeanintraocularpressureofover7mmHg(30%)atthetimeofthepatient'slastvisitwasnotedinthetreatedeye.Surgeryandmedicaltherapyhavebeenemployedsincethe19thcenturytolowerintraocularpressureinpatientswithglaucoma,butinthepastfewyearsargonlasertherapyhasgraduallybeengainingacceptanceasanewmethodoftreatmenteithertosupplementortoreplacetheseoptions.Initiallyintheearly1970sahighintensitylaserbeamwasusedtoperforatethetrabecularmeshworkandenterthecanalofSchlemm.'Thisapproachachievedonlyatemporarypressurereductionbecauseofthehealingofthemicropuncturesites.Itwassubsequentlyfoundthatextensivelaserapplica-tiontotheanteriorchamberangleinmonkeyscouldactuallyinduceglaucoma.2In1979,however,adifferentapproachwasproposed.34Byusingtheargonlaserwithafarlowerpowersettingsoastoinducecontractionratherthanpunctureofthecollageninthetrabecularmeshwork,amuchlonger-lastingreductionofintraocularpressurewasachieved.Followingthis3andother"encouragingreportsfromtheUSAaprospectivetrialwassetupattheGlaucomaUnit,MoorfieldsEyeHospital,toinvestigatetheeffectsoflasertrabeculoplastyinadiscrete,butclinicallythemostcommon,group-namely,elderlypatientswithprimarychronicopenangleglaucoma.pressure(above21mmHg),glaucomatousdiscchange,andvisualfieldloss.(b)Nopreviouseyesurgerynorevidenceofothereyedisease.(c)Patientsalreadytakinginbotheyesthemaxi-mumantiglaucomamedicationthatcouldbetolerated(Fig.1).Inmostcasesthiswouldhavebeenaminimumoftwoandamaximumoffouranti-glaucomamedicines(timolol,pilocarpine,sympa-thomimetics,andacetazolamideinvaryingcombina-tions).Yetdespitethistreatmenttheintraocularpressurewasconsistentlyexceeding21mmHgandconsideredtobeinadequatelycontrolled.Beforelasertreatmentwasgivenabaselineophthalmologicalexaminationwasperformedandfullhistoryrecorded.The'initialintraocular60_50-30-20-PatientsandmethodsAhighlydefinedgroupofelderlypatientswasselectedaccordingtothefollowingcriteria:(a)Bilateralprimaryopenangle(simple)glaucomaasjudgedbyelevationofintraocularCorrespondencetoRAHitchings,FRCS.188100BEFOREALTJPOSTALTI1I--u-I012NUMBEROFMEDICATIONSFig.1Reductioninmedicationafterlasertreatment.ALT=argonlasertreatment.IavInol:,,I1"z';AIsII1-IF Lasertrabeculoplastyassupplementarytreatmentforprimaryopenangleglaucomapressure'ineacheye,bymeansofaGoldmannapplanationto
nometer,wastakenastheaveragepressureofthelastthreeclinicvisits.Oneeyewasthenrandomlyselectedbycomputerforlasertherapy,theothereyeactingasacontrol.Thelasertrabeculoplastyconsistedofasingleoutpatientsittingatwhich100evenlyspaced,lowintensitybums01seconddurationwereappliedwithacontinuouswaveargonlaser(LaserTek)andGoldmannthree-mirrorcontactlens,tothe360°ofthemidtrabecularmeshwork.8Inthefirstsixpatientsaspotsizeof350[Lmwaschosen;andfortheremainder150Rmwasemployedbecauseofdifficultiesinfocusingthelarger350iumspot.Thepowerwasadjustedforeachindividualtogiveanendpointofblanchingandminimalvaporisa-tionbubbling.Itwasfoundthatapowersettingof0-5to1wattwasusuallysufficient.Afterlasertreatmentthepreviousmaximumtoleratedmedicaltherapywascontinuedtobotheyesand,inadditiontothetreatedeyeonly,prednisolonedrops01%qidwereaddedforaboutoneweek.Thepatientswerereviewedonaregularbasis,initiallyatfrequentintervalsandthenlatereverythreemonths.Nearlyallthepostlasertonometryreadingswerecheckedbytwoindependentobservers,oneofwhomwasaglaucomatechnicianwhohadnoknowledgeofwhicheyehadreceivedtheargonlasertrabeculo-plasty.Theglaucomavisualfieldswerealsoassessedbytwoobservers,oneofwhomwastheseniorglaucomafieldtechnician,andwhoagainwasunawareofthepatient'spastlaserhistory.Itwasdecidedattheoutsetofthetrialthat,ifthelasertreatmentproducedapersistentloweringofIOPlastingforoneyear,thesametreatmentwouldbeofferedtothe'untreated'eye.Atthesametimeanattemptwouldbemadetowithdrawsomeoralloftheantiglaucomatreatmentgiventothe'treatedeye'.ResultsTwenty-fivepatientswereinitiallyincludedinthestudy;theirmeanagewas72.5yearsatthestart(range56to90).Ofthese,onediedsixmonthsafterlasertreatmentandwasexcluded,thoughhisintra-ocularpressurehadfallenfromabaselineof22mmHgto16mmHgathislastreading.The24survivingpatientshadaminimumfollow-upof21/2years(range30to40months,mean35months).Onepatientwascommittedtoaninstitutionwithseniledementiaandhisconditionwassuchthatitwasimpossibletoobtainaccuratevisualfields,thoughhisintraocularpressureshavebeenfollowedup.Beforelasertrabeculoplastythemeanintraocularpressuresontreatmentweresimilarinthelasertreatedanduntreatedeyes(23.8mmHg).Afterlasertreatmenttherewas,byonemonth,asignificantfallinthemeanpressureinthetreatedeyewhichhaslargelybeenmaintained.Atransientinitialfallintheuntreatedeyewasalsoseen(Table1,Fig.2).Afteroneyearattemptsweremadetoreducethemedicationasfaraspossibleinthetreatedeyewhilestillmaintainingadequatecontroloftheglaucoma.Threeofthe24survivingpatients(13%)wereabletoNON-TREATEDEYENOWLASEREDAFTER12MONTHSFig.2IntraocularpressurechangesplottedagainsttimeinpatientsreceivinglasertrabeculoplastycomparedwiththosenotreceivinglasertrabeculoplastyforthefirstoneyearoftheStudy.13691215TIME(months)18212427303336189 MarkBSherw
ood,JohnLattimer,andRogerAHitchingsTable1ComparisonofintraocularpressureinpatientsafterlasertrabeculoplastytooneeyeTime(months)No.ofpatientsLaseredeyemeanNon-laseredeyemeanComparisonofmeanpValueintraocularpressureintraocularpressureintraocularpressurenon-(mmHg)(mmHg)laseredtolaseredeyeBaseline2423-823-8012414-922-07-132415-122-27-162415-522-87-392415-422-77-31223*15-022-17-11523*16-31823t16-7212417-8242417-0272416-33023t16-0331716-836818-6*Onepatientwithirregularfollow-upatthistime.tIrregularfollow-upatthisstageinpatientinstitutionalizedwithseniledementia.tOnepatientunderwenttrabeculectomysurgeryat27monthsafterargonlasertrabeculoplasty.stopalltreatment,whileafurther11(46%)cameoffsomeoftheirmedications.Onepatient,whowasapoorcomplier,hadacetazolamidetabletsaddedtohisbaselineeyedropregimen.Themeannumberofdifferentantiglaucomamedicationstakenbeforelasertreatmentwas2.3perpatientandattheirlastvisit1-6perpatient(Fig.1).Nineteenofthe23(83%)patientsinwhomithasbeenpossibletoobtainGoldmannvisualfieldanalyseshavemaintainedstablevisualfields.Oftheremainingfourcasestwohaveshownslightfieldprogressiondespiteintraocularpressuresconstantlyrecordedbelow21mmHg(meanintraocularpressure12mmHgand18mmHgrespectively).However,thesefindingsdidnotdiffersignificantlyfromthevisualfieldchangesseeninthecontroleye.Ifsuccessoflasertreatmentisdefinedinintra-ocularpressuretermsas(a)afallofintraocularpressureofatleast20%frombaseline(meanoflastthreereadings)andinaddition(b)nointraocularpressurereadingsabove21mmHg,thentreatmentin19ofthe24patients(79%)wasasuccesswithaminimumfollow-upof2/2years.Ofthefivefailuresbytheabovecriteriathreefailedafteroneyear('latefailures'),andoneoftheserequiredfiltrationsurgeryat27monthsafterargonlasertrabeculoplasty.DiscussionArgonlasertrabeculoplastywasabletoproduceaclinicallyusefulfallinintraocularpressureofmorethan7mmHg(30%)inthisgroupofelderlypatientswithchronicsimpleglaucomawhowerealreadytakingthemaximummedicaltherapythattheycouldtolerate.Inover80%ofpatientsnofurtherlossofvisualfieldhasoccurredsofar,thoughthisdidnotdiffersignificantlyfromthecontrolgroup.(Ithastoberememberedthattheintraocularpressuresinthesecontroleyesremainedinexcessof21mmHgonlyforthefirst12monthsofthestudy,afterwhichtimetheseeyestoowouldhavebeentreatedwithlasertrabeculoplasty.)Theeyestreatedinthisstudyreceivedlaserenergyto3600ofthetrabecularmeshworkatonetime.Morerecentworkhasshownthatthistreatmentcouldresultinatemporaryincreaseofintraocularpressure.9Wenowgivethesame3600treatmentintwoseparatesessions,treatingonehalfofthetrabecularmeshworkeachtime,andimmediatelyaftereachsessioninstilpilocarpineinanattempttominimiseanytransientocularhypertension.WiseandWitter'soriginaldescriptionrecom-mendedtheuseofaspotsizeof50Rm.3In-vitrostudiessugges
tthatalargerspotsizemaybemoreefficacious.'0Aclinicalstudycomparingtheuseofdifferentspotsizessupportsthisview(LattimerandHitchings,inpreparation).Theresultsobtainedbyourtechniqueusing150,umspotssizecertainlycomparewellwiththoseobtainedby�-00;áothers.'Duringthefirstyearofthestudytheintraocularpressuresinthe'control'groupshowedamarkedfalloverthefirstonetotwomonths(Fig.2).Weconsideredthatthiswasaplaceboeffect,fortheintraocularpressuresinthisgroupthenrosetotheprestudylevelswithoutanyalterationsinmedicationhavingtakenplace.Weconsiderthatthisresponsehighlightstheimportanceofrestrictingthenumberofvariablesinaprospectiveclinicalstudy.Afteroneyearoffollow-up,asFig.2shows,asteadystateinintraocularpressurelevelshadbeenreached.Thusit190 Lasertrabeculoplastyassupplementarytreatmentforprimaryopenangleglaucomawasconsideredreasonablenotonlytotreatthecontrolgroupwithlaserbutalsototrytowithdrawantiglaucomamedicinesfromthetreatedgroup..Thegoodresultsoflasertrabeculoplastyinpatientswhoarealreadyonafullmedicalregimenledtotheideaofusingthelaserearlierinthediseaseprocessandindeedastheprimarytreatmentofcertaintypesofglaucoma.Studiesarealreadyunderwaytoinvestigatethispossiblenewroleforlasertherapyinthemanagementofprimaryopenangleglaucoma,andpreliminaryresultsareencourag-ing.8'1112Thestudywassupportedbythelocallyorganisedresearchscheme,GMC.References1KrasnovMM.Laseropunctureoftheanteriorchamberangleinglaucoma.AmJOphthalmol1973;75:674-8.2GasterlandD,KupferC.Experimentalglaucomainrhesusmonkeys.InvestOphthalmolVisSci1974;13:455-7.3WiseJB,WitterSL.Argonlasertherapyforopenangleglaucoma:apilotstudy.ArchOphthalmol1979;97:319-22.4WiseJB.Longtermcontrolofadultopenangleglaucomabyargonlasertrabeculoplasty:Ophthalmology(Rochester)1981;88:197-202.5SchwartzAL,WhittonME,BleimanB,MartinD.Argonlasertrabecularsurgeryinuncontrolledphakicopenangleglaucoma.Ophthalmology(Rochester)1981;88:203-12.6PohjanpeltoP.Argonlasertreatmentoftheanteriorchamberangleforincreasedintraocularpressure.ActaOphthalmol(Kbh)1981;59:211-20.7WilenskyJT,JampolLM.Lasertherapyforopenangleglaucoma.Ophthalmology(Rochester)1981;88:213-7.8MigdalC,HitchingsRA.Primarytherapyforchronicsimpleglaucoma.Theroleofargonlasertrabeculoplasty.TransOphthalmolSocUK1985;104:62-6.9WeinrebRN,RudermanJM,JusterR,ZweigKO.Immediateintraocularpressureresponsetoargonlasertrabeculoplasty.AmJOphthalmol1983;95:279-86.10PeiJ,DuekerDK,GrantWM.Responseoftrabecularmesh-worktoheating.ARVOAbstract1983;24:88.11RosenthalAR,ChaudhuriPR,ChiapellaAP.Lasertrabeculo-plastyprimarytreatmentinopenangleglaucoma:apreliminaryreport.ArchOphthalmol1984;102:699-701.12ThomasJV,El-MoftyA,HamdyEE,SimmonsRJ.Argonlasertrabeculoplastyasinitialtherapyforglaucoma.ArchOphthalmol1984;102:702-3.AcceptedforpublicationIMay1986.