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Comparison of excimer lasers

There are different excimer laser platforms for the correction of visual defects in refractive surgery (myopia, hyperopia, astigmatism, presbyopia). Currently, 9 platforms are vying for the bulk of the market: they rely on the use of Excimer radiation 193 nm (argon – fluorite). Seven use technology by Spot Scan (Allegreto, WaveLight, Zeiss Meditec, Schwind lasers), a rotating slit scanning (Nidek), and only the VISX laser uses the issuance of variable-size beams (VSS: variable spot scanning for customised treatments).

Excimer Laser Platforms

Presentation of the main Excimer laser platforms used in refractive surgery.

The main features of these Excimer laser platforms are listed in the following table. The most recent are the laser WaveLight ex 500 (2011) and the Laser Schwind Amaris (2009). Some platforms are older, but have been able to benefit from secondary additions and improvements, sometimes presented as novelties, but often rather in compliance (For example, see the case of the tissue ablation reduction or "tissue saving" option ): However and despite these successive improvements, older lasers (Technolas Z100, Mel 80, VISX S4) do not benefit from certain technologies such as the real-time measurement of the residual corneal thickness, or the possibility to realize a personalized centring to the corneal vertex (visual axis).

Table 1: Comparison of the 3 WaveLight laser models and the AMO model.

 

CompanyWaveLightWaveLight
WaveLight
Amo
ModelAllegretto waveAllegretto Wave Eye-QWaveLight EX 500S4/IR
Working distance mm]200200250210
Source Laser ArfArfArfArf
Frequency Shots 200 Hz400 Hz500 Hz 6 Hz to 20
Pulse duration10 NS10 NS< 7 NS20ns
Ablation Flying spotFlying spotFlying spotSpottaillevariable
Beam profile3d Gaussian3d Gaussian3d GaussianFlat Top
 Average Fluence200 MJ/cm2200 MJ/cm2200 MJ/cm2160 MJ/cm2
Size Beam Fwhm)0.68 mm0.68 mm0.68 mmVariable  (0.65-6.5 mm)
Spot size   Ablation threshold0.95 mm/max. 1 mm 0.95 mm/max. 1 mm 0.95 mm/max. 1 mm 0, 65 – 6, 5 mm                  (0.7 mm-6, 9 mm)
Ablation depth by Pulse0.65 µm0.65 µm0.65 µm0.38 µm
Ablation depth by Diopter Myopia     (Zo 6, 5 mm)15.5 µm 15.5 µm 15.5 µm 16 Μ (7 s)
Time/diopter myopia (zo = 6.0 mm)3,5 s1,7 s1.4 s6 s
Time/diopter Hyper-Métropie zo = 6.0 mm<8 s<4s3 s26 s
Ablation depth
-5DPT
Zo = 6 mm
Μm
63.2 (17 s)63.2 (8 s)63.2 (6.5)63 (29s)                      
71 (32 s) VSS 
Sampling EyetrackerHz2504001050 HzHz
Response timeEye Trackr6 – 8 ms6 – 8 ms2 – 3 DC16-24 ms
FixingPatient Flashing Green LED Flashing Green LED Flashing Green LEDDiode laser
 Optical areas Zo)4.5 mm (ZO)4.5 mm (ZO)4.5 mm (ZO)6.00 and 6.50 mm
Ablation AreaZo + 0.7 mm myopia, Zo + 2.5 mm AST, 9.00 mm Hyperopia Zo + 0.7 mm myopia, Zo + 2.5 mm AST, 9.00 mm Hyperopia Zo + 0.7 mm myopia, Zo + 2.5 mm ast., 9.00  MM Hyperopia 8.00 mm myopia,                   9, 00mmhyperopie
Ablation profile
Wavefront optimizedWavefront optimizedWavefront optimizedMunnerlyn/or VSS
Area Transition
Fixed/AdjustableFixed/AdjustableFixed/AdjustableFixed myopia, Ajustablehyperopie
Wavefront LinkYesYesYesYes (Wavescan)
Link topographyYes                                     Oculyzer & TopolyzerYes                                     Oculyzer & TopolyzerYes                                     Oculyzer & TopolyzerNo
Treatment topographyYesYesYesNo
Fluence & CalibrationFluence Objective Fluence Objective Fluence Objective Manual & Subjective 
Pachymetry OnlineNoNoYesNo
Debris Evacuation FeatherYesYesIntegratedYes

Table 2: Comparison of Zeiss, Nidek, Technolas Perfect vision, and schwind lasers

 

CompanyCarl Zeiss MeditecNidekTEchnolas Perfect VisionSchwindSchwind
ModelMel 80EC 5000 CXIII/ QuestTechnolas 217 Zyoptix 100EsirisAmaris
Working distance mm]190200215295235
SourceLaserArfArfArfArfArf
Frequency Shots 250 Hz5, 10, 20, 30, 40, 50 Hz (PTK myopia),                   34, 41, 46 Hz, Hyperopia 100 Hz200 Hz500 Hz
Duration Pulse5 NS25 NS18 NS12 NS10 NS
Ablation Flying spotSweeping and multipoint slit Flying spot Flying spotFlying spot
Beam profileGaussian Flat Top2 mm Flat Top & 1 mm Gaussian truncatedPara-GaussianSuper Gaussian
 Average Fluence150 MJ/cm2300 MJ/cm2120 MJ/cm2160 MJ/cm2160mJ/cm2 – 450mJ/cm2
Size Beam (FWHM)0.7 mm ± 0.1 mm10 x 2 mm slot    (1 mm for custom)2 mm & 1 mm Gaussian truncated (TS, aspheric.) Pt,  PTA and Presby)0.8 mm0.54 low fluence, 0.68 in high fluence
Spot size ablation threshold0.7 mm     (1.3 mm)1.0 mm1.0 mm – 2.0 mm0.9 mm0.54  Low fluence (0.7 mm), 0.68 (0.8 mm) high Fluence
Ablation depth by Pulse0.51 µm0.32 Μm0.25 Μm0.39 µm0.42 µm – 0.68 µm
Ablation depth by Diopter Myopia (zo 6, 5 mm)       
16 Μm Fabric Saving
19 Μm (11s)20 Μm (PlanoScan)    (TissueSaving)        25 Μm (Aspheric)16.5 µm16.4 µm
Time/diopter Myopia (zo 6.0 mm)                   
 3s tissue saving 
9 S (16 µm)7 s (PlanoScan 18 µm)   6 7 s (Tissue saving 18 µm)  8 S (aspheric 22 µm) 11 s<2,5 s
Time/Diopter Hyper-Métropie (zo 6.0 mm)14 S (PlanoScan 21 µm)<4.5 s
Ablation depth
-5DPT/ Zo = 6 mm
65 Μm (18s)          
77 Μ for ASA
74.7 Μm (43 s)87 Μm (PlanoScan 36s)   67 Μm (TissueSaving 18s)   75 µm (Aspherique 24s) 65 Μm (32s)       65 Μm (12s)
SamplingEye Tracker Hz250/1050 Hz (optional)200/1000 Hz (optional)Hz330 Hz1050 Hz
Response time Eye Tracker<6,0 ms  <5,0 ms10.75 ms3.3 ms 1 ms (< 3 ms)
Patient fixation Flashing Green LEDRed LEDRed LEDFlashing Red LED Flashing Green LED
 Optical areas Zo)5.00 mm –  8.00 mm6.5 mm 3, 6 mm-7 Planoscan,            ˙-8.5 mm fabric saving4 – 10 mm 4 – 10 mm 
Ablation AreaZa up to 10 mm, ZT 1.7 mm to 1.9 mm 10 mm max.10OptimizedOptimized
Ablation profileAberration smart ablation, (ASA)Munnerlyn, OATZ (Aspherical), Opa (prolate) and H70 (Hypermétropiezone large 7.00 mm)Aspherical wavefront (Zyoptix)Aspherical (free aberration)Aspherical (free aberration)
Transition zoneFixedNoNo
Wavefront LinkYesYes                                  OPD-Scan IIIYesYesYes
Link topographyYes (Atlas  Humphrey)Yes                                  OPD-Scan IIIYes                                  Orbscan II (ZYOPTIX)Corneal wavefront Analyzer/CSOCorneal wavefront Analyzer/CSO
Treatment topographyYesYesNoYes (corneal wavefront)Yes (corneal wavefront)
Fluence & CalibrationManual & Subjective Manual & Subjective Manual and Subjective Automatic & ObjectiveAutomatic & Objective
Pachymetry OnlineNoNoNot)YesYes
Debris Evacuation FeatherYesNoNoNoYes

 

 

 

 

 

 

CompanyWaveLightWaveLightWaveLightAmo

Carl Zeiss Meditec
NidekTechnolas Perfect VisionSchwindSchwind
ModelAllegretto waveAllegretto Wave Eye-QWaveLight EX 500S4/IRMel 80EC 5000 CXIII/QuestTechnolas 217 Zyoptix 100EsirisAmaris
working distance [mm]200200250210190200215295235
Laser sourceArfArfArfArfArfArfArfArfArf
Firing frequency 200 Hz400 Hz500 Hz 6 Hz to 20250 Hz5, 10, 20, 30, 40, 50 Hz (PTK myopia),                   34, 41, 46 Hz, Hyperopia 100 Hz200 Hz500 Hz
Pulse duration10 NS10 NS< 7 NS20ns5 NS25 NS18 NS12 NS10 NS
Ablation Flying spotFlying spotFlying spotSpot size variableFlying spotSweeping and multipoint slit Flying spot Flying spotFlying spot
Beam profile3d Gaussian3d Gaussian3d GaussianFlat TopGaussian Flat Top2 mm Flat Top & 1 mm Gaussian truncatedPara-GaussianSuper Gaussian
 Average Fluence200 MJ/cm2200 MJ/cm2200 MJ/cm2160 MJ/cm2150 MJ/cm2300 MJ/cm2120 MJ/cm2160 MJ/cm2160mJ/cm2 – 450mJ/cm2
Beam size (FWHM)0.68 mm0.68 mm0.68 mmVariable  (0.65 – 6.5 mm)0.7 mm ± 0.1 mm10 x 2 mm slot    (1 mm for custom)2 mm & 1 mm Gaussian truncated (TS, aspheric.) Pt,  PTA and Presby)0.8 mm0.54 low fluence, 0.68 in high fluence
Spot size   @ ablation Threshold0.95 mm/max. 1 mm 0.95 mm/max. 1 mm 0.95 mm/max. 1 mm 0, 65 – 6, 5 mm                  (0, 7 mm – 6, 9 mm)0.7 mm     (1.3 mm)1.0 mm1.0 mm – 2.0 mm0.9 mm0.54  Low fluence (0.7 mm), 0.68 (0.8 mm) high Fluence
Pulse ablation Depth0.65 µm0.65 µm0.65 µm0.38 µm0.51 µm0.32 Μm0.25 Μm0.39 µm0.42 µm – 0.68 µm
Diopter ablation Depth  myopia      (Zo 6.5 mm)15.5 µm 15.5 µm 15.5 µm 16 Μ (7 s)       
16 Μm Fabric Saving
19 Μm (11s)20 Μm (PlanoScan)    20 Μm (TissueSaving)        25 Μm (Aspheric)16.5 µm16.4 µm
Time/Diopter Myopia       (Zo 6.0 mm)3,5 s1,7 s1.4 s6 s                   
 3s tissue saving 
9 S (16 µm)7 s (PlanoScan 18 µm)   6 s (Fabric saving 18 µm)   8s (aspheric 22 µm) 11 s<2,5 s
Time/Diopter         Hyper-  Métropie    (Zo 6.0 mm)<8 s<4s3 s26 s14 S (PlanoScan 21 µm)<4.5 s
Ablation depth
-5DPT/zo = 6 mm
63.2 (17 s)63.2 (8 s)63.2 (6.5 s)63 Μ (29 s)                      
71 Μ (32 s) VSS 
65 Μm (18s)          
77 Μ for ASA
74.7 Μm (43 s)87 Μm (Plano Scan 36 s)   67 Μm (TissueSaving 18s)   75 µm (Aspheric 24s) 65 Μm (32s)       65 Μm (12s)
Sampling Eye Tracker Hz2504001050 HzHz250/1050 Hz (optional)200/1000 Hz optionalHz330 Hz1050 Hz
Eye Tracker Response Time6 – 8 ms6 – 8 ms2 – 3 DC16-24 ms<6,0 ms  <5,0 ms10.75 ms3.3 ms 1 ms (< 3 ms)
Patient fixation Flashing Green LED Flashing Green LED Flashing Green LEDDiode laser Flashing Green LEDRed LEDRed LEDFlashing Red LED Flashing Green LED
 Optical zones (ZO)4.5 mm (ZO)4.5 mm (ZO)4.5 mm (ZO)6.00 and 6.50 mm5.00 mm –  8.00 mm6.5 mm 3, 6 mm-7 Planoscan,            ˙-8.5 mm fabric saving4 – 10 mm 4 – 10 mm 
Ablation AreaZo + 0.7 mm myopia, Zo + 2.5 mm AST, 9.00 mm Hyperopia Zo + 0.7 mm myopia, Zo + 2.5 mm AST, 9.00 mm Hyperopia Zo + 0.7 mm myopia, Zo + 2.5 mm ast., 9.00  MM Hyperopia 8.00 mm myopia,                   9.00 mm HyperopiaZa up to 10 mm, ZT 1.7 mm to 1.9 mm 10 mm max.10OptimizedOptimized
Ablation profileWavefront optimizedWavefront optimizedWavefront optimizedMunnerlyn/or VSSAberration smart ablation, (ASA)Munnerlyn, OATZ (Aspherical ablation), OPA (prolate) and h70 (hyperopia zone large 7.00  mm)Aspherical wavefront (Zyoptix)Aspherical (free aberration)Aspherical (free aberration)
Transition zoneFixed/AdjustableFixed/AdjustableFixed/AdjustableFixed myopia, adjustable hyperopiaFixedNoNo
Wavefront LinkYesYesYesYes (Wavescan)YesYes                                  OPD-Scan IIIYesYesYes
Link topographyYes                                     Oculyzer & TopolyzerYes                                     Oculyzer & TopolyzerYes                                     Oculyzer & TopolyzerNoYes (Atlas  Humphrey)Yes                                  OPD-Scan IIIYes                                  Orbscan II (ZYOPTIX)Corneal wavefront Analyzer/CSOCorneal wavefront Analyzer/CSO
Treatment topographyYesYesYesNoYesYesNoYes (corneal wavefront)Yes (corneal wavefront)
Fluence & CalibrationFluence Objective Fluence Objective Fluence Objective Manual and Subjective Manual and Subjective Manual and Subjective Manual and Subjective Automatic and objectiveAutomatic and objective
Pachymetrie OnlineNoNoYesNoNoNoNot)YesYes
Debris Evacuation FeatherYesYesIntegratedYesYesNoNoNoYes
CompanyCarl Zeiss MeditecNidekTechnolas Perfect VisionSchwindSchwind
ModelMel 80EC 5000 CXIII/QuestTechnolas 217 Zyoptix 100EsirisAmaris
working distance [mm]190200215295235
Laser sourceArfArfArfArfArf
Firing frequency 250 Hz5, 10, 20, 30, 40, 50 Hz (PTK myopia),                   34, 41, 46 Hz, Hyperopia 100 Hz200 Hz500 Hz
Pulse duration5 NS25 NS18 NS12 NS10 NS
Ablation Flying spotSweeping and multipoint slit Flying spot Flying spotFlying spot
Beam profileGaussian Flat Top2 mm Flat Top & 1 mm Gaussian truncatedPara-GaussianSuper Gaussian
 Average Fluence150 MJ/cm2300 MJ/cm2120 MJ/cm2160 MJ/cm2160mJ/cm2 – 450mJ/cm2
Beam size (FWHM)0.7 mm ± 0.1 mm10 x 2 mm slot    (1 mm for custom)2 mm & 1 mm Gaussian truncated (TS, aspheric.) Pt,  PTA and Presby)0.8 mm0.54 low fluence, 0.68 in high fluence
Spot size   @ ablation Threshold0.7 mm     (1.3 mm)1.0 mm1.0 mm – 2.0 mm0.9 mm0.54  Low fluence (0.7 mm), 0.68 (0.8 mm) high Fluence
Pulse ablation Depth0.51 µm0.32 Μm0.25 Μm0.39 µm0.42 µm – 0.68 µm
Diopter ablation Depth  myopia      (Zo 6.5 mm)       
16 Μm Fabric Saving
19 Μm (11s)20 Μm (PlanoScan)    20 Μm (TissueSaving)        25 Μm (Aspheric)16.5 µm16.4 µm
Time/Diopter Myopia       (Zo 6.0 mm)                   
 3s tissue saving 
9 S (16 µm)7 s (PlanoScan 18 µm)   6 s (Fabric saving 18 µm)   8s (aspheric 22 µm) 11 s<2,5 s
Time/Diopter         Hyper-  Métropie    (Zo 6.0 mm)14 S (PlanoScan 21 µm)<4.5 s
Ablation depth
-5DPT/zo = 6 mm
65 Μm (18s)          
77 Μ for ASA
74.7 Μm (43 s)87 Μm (Plano Scan 36 s)   67 Μm (TissueSaving 18s)   75 µm (Aspheric 24s) 65 Μm (32s)       65 Μm (12s)
Sampling Eye Tracker Hz250/1050 Hz (optional)200/1000 Hz optionalHz330 Hz1050 Hz
Eye Tracker Response Time<6,0 ms  <5,0 ms10.75 ms3.3 ms 1 ms (< 3 ms)
Patient fixation Flashing Green LEDRed LEDRed LEDFlashing Red LED Flashing Green LED
 Optical zones (ZO)5.00 mm –  8.00 mm6.5 mm 3, 6 mm-7 Planoscan,            ˙-8.5 mm fabric saving4 – 10 mm 4 – 10 mm 
Ablation AreaZa up to 10 mm, ZT 1.7 mm to 1.9 mm 10 mm max.10OptimizedOptimized
Ablation profileAberration smart ablation, (ASA)Munnerlyn, OATZ (Aspherical ablation), OPA (prolate) and h70 (hyperopia zone large 7.00  mm)Aspherical wavefront (Zyoptix)Aspherical (free aberration)Aspherical (free aberration)
Transition zoneFixedNoNo
Wavefront LinkYesYes                                  OPD-Scan IIIYesYesYes
Link topographyYes (Atlas  Humphrey)Yes                                  OPD-Scan IIIYes                                  Orbscan II (ZYOPTIX)Corneal wavefront Analyzer/CSOCorneal wavefront Analyzer/CSO
Treatment topographyYesYesNoYes (corneal wavefront)Yes (corneal wavefront)
Fluence & CalibrationManual and Subjective Manual and Subjective Manual and Subjective Automatic and objectiveAutomatic and objective
Pachymetrie OnlineNoNoNot)YesYes
Debris Evacuation FeatherYesNoNoNoYes

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