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Customized Ablation:Wavefront – Guided orAspheric ?Michael C. KnorzFreeVis LASIK Center,Medical Faculty Mannheim of the University of Heidelberg,Mannheim, Germany
Which is best ? Aspheric („Wavefront – Optimized“)ablation Wavefront – Guided Ablation Topography – Guided Ablation
Topography – Guided Ablation Ablation designed to achieve a „normal“corneal topography Very useful in highly aberrated corneas,e.g., after previous laser refractivesurgery No information on the total aberrationsof the eye AND on refraction !!
Aspheric („Wavefront –Optimized“) Ablation Ablation designed to minimze inducedspherical aberration– Prolate shape of cornea maintained This is NOT a customized ablation asSA of the eye is typically NOTmeasured !!
Wavefront – Guided (WFG) Aberrometry Calculation of customized ablation Iris registration WFG IS a customized ablation Iris registration possible with WFGonly !
„Iris Registration“ Aligns WaveScan image and ablation– Compensates for cyclotorsion– Compensates for pupil centroid shift
-5.00 -1.50 x 79 6 mm PupilPerfect Case: No Centroid Shift/CyclotorsionResidual Refraction Plano Coma 0 Spherical Aberration 0
Centroid Shift x 0.26 mm, y 0.13 mmCyclotorsion 3.21Residual Refraction 0.37 -0.23 x 41º Coma 0.37 µm Spherical Aberration -0.34 µm
Centroid Shift x 0.5 mm, y 0.5 mmCyclotorsion 9.7ºResidual Refraction 1.31 -1.14 x 51º Coma 0.97 µm Spherical Aberration -0.77 µm
Iris Registration Alignement of the ablation improvesresults of astigmatism correction ANDwavefront correction
Studies
Experimental Comparison of WFGAblation vs Aspheric (“optimized”)and Standard AblationSteve Schallhorn, MD
Mean Change in HOA 0All eyesNormalNeg sph abHighly aberrated
Simulated Tx - Normal pre-opConventionalAsphericWFG HOA: 0.21 µm HOA: 0.14 µm HOA: 0.08 µm
Summary SchallhornBased on the simulations:– Aspheric (“optimized”) LASIK is animprovement over conventional, however itstill induces more HOAs than Wavefrontguided LASIK– WFG LASIK is superior to Aspheric(“optimized”) LASIK
Customized Treatments:Advantages and LimitationsJack T. Holladay, MD, MSEE, FACSClinical Professor of OphthalmologyBaylor College of MedicineHouston, Tx
StudyRetrospective Chart Review of IntraLASIK (2005Q4-6) 102 Eyes: Intralase Wavelight 109 Eyes: Intralase Visx CustomVue Range of Treatment: 3.00 to -11.00 D, 0 to 3 D AstigPreop and Postop Wavefronts on ALL EYESOPD Scan: All analyzed at 6 mm pupilAnalyzed ALL HO, Spherical, Coma, Trefoil AberrationsUCVA & BSCVA with 98% HC, 5% LC and VC (78% -1%)109 CustomVue (GUIDED) and 102 Wavelight (OPTIMIZED)
WFG Retreatments - Case 1 LASIK OU -5 sph (B&L 217z100) OD -1.50, „halos around lights“ Visx CustomVue Retreatment– Pre-OP -1.55 sph -0.16 cyl / 79 – Post-OP: plano, UCVA 20/15– „no halos, vision better than with glasses“
WFG Retreatments - Case 2 LASIK OU -3.5 sph (B&L 217z100) OD -1.00 cyl / 0 , „second image“ Visx CustomVue Retreatment– Pre-OP 0.57 sph -1.1 cyl / 5 – Post-OP: plano, UCVA 20/20– „perfect vision“
Conclusions Aspheric („optimized“) Ablation:– Minimizes induction of sphericalaberration– Represents minimum requirement today(spherical ablations are obsolete !)– Cannot be used in aberrated eyes ! (e.g.,complicated retreatments, etc.)
Conclusions Wavefront – Guided Ablation:– Minimizes not just spherical aberrationbut all aberrations– Provides only way to truly customize theablation– Provides only way to perfectly align lasertreatment
Thank you !
102 Eyes: Intralase Wavelight 109 Eyes: Intralase Visx CustomVue Range of Treatment: 3.00 to -11.00 D, 0 to 3 D Astig Preop and Postop Wavefronts on ALL EYES OPD Scan: All analyzed at 6 mm pupil Analyzed ALL HO , Spherical , Coma , Trefoil Aberratio
