准分子雷射近视屈光手术ppt培训课件

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1、準分子雷射(近視)屈光手術ExcimerLaserRefractiveSurgery基督教門諾會醫院眼科NoRefractiveErrorEmmetropia正視Nearsighted:Myopia近視Astigmatism亂視(散光)Farsighted:Hyperopia遠視屈光的四大要素(決定是否有近視)*角膜：42D左右的屈光度*前房*水晶體：15D左右的屈光度(調節機能假性近視*眼軸長度：23mm~24mm(每增加1mm,度數增加2.50D)近視手術的主要原理1.降低眼球屈光度透明水晶體摘除術置入小凹透鏡2

2、.縮短眼軸長度放射狀角膜切開術（RK）自動角膜層狀重塑術（ALK）雷射屈光角膜切除術（PRK）雷射角膜層狀重塑術(LASIK)近視手術的沿革1930Sato:Internalkeratotomy1979Fyderov:RadialKeratotomy1961Barraquer:Keratomileusis,ALK1989Trokel:PRK(ExcimerLaser)1990LASIK放射狀角膜切開術RadialKeratotomyCornealscarsresultingfromRK何謂準分子雷射excimerlas

3、er?EXCIMER=ExcitedDimerLASER=LightAmplificationbyStimulatedEmissionofRadiationExcimerLaserTheoryInthelasercavityArFgasisexcitedby25,000to30,000Volts.Thelightdischargeistheresultofthisexciteddimerreturningtoitsgroundstatefromthisstateofexcitation.Thewavelengthofl

4、ightgeneratedisdependentuponthegasesusedinthelasercavity(ArF=193nm)CloseupofanIBMlogoinscribedonahumanhairCourtesyofIBMTheHumanHair(125microns)EtchedwithanexcimerlaserThermalNon-thermalExcimerCO2YAGEffectsofLaserAblationCornealTissueImpactTissueplumeafterimpact

5、CourtesyofCarmenPuliafito,M.D.Uncouplingofintermolecularbondsbydirectutilizationofhigh-energyphotons.At193nm(ArF)eachphotonhasanenergyof6.4eVTheoryofPhotoablationAblativePhotodecompositionHighEnergy(bondbreaking6.4eV)PrimarilyNon-ThermalMinimalornocollateraltiss

6、uedamageHighlycontrolled(approx.0.25micronsablated/pulse)Expandingshockwavefollowedbyejectionofdebris(3000m/sec)ArFExcimer-193nmVISXSTAR™S3ActiveTrakExcimerLaserSystemPRK:MyopiaLASIK(LaserAssistedIn-SituKeratomileusis)LASIK是合併ALK與準分子雷射的一種手術方法。先以角膜顯微刨刀(AutomatedM

7、icroKeratome)將角膜削開一層表皮瓣，約160um厚‘直徑8.5-9.0mm將其掀開，然後由準分子雷射切削角膜基質進行屈光矯正，準分子雷射遠比ALK精確，副作用也較少。HansatomeMicrokeratomeSystemSinglepass,multi-zoneforhighmyopiaCorrectionCentralDepth6mm5mm4mmTotal(Diopters)(Microns)ZoneZoneZoneDepth-10.0013228272782-15.00196424040122-2

8、0.00259565454164MultiPass/MultiZoneCourtesyofMihaiPop,M.D.OpticalZoneIssuesTheopticalzonesizemustbelargerthanthepatient’spupilsizetoavoidnighthalosandghostimages.Trea