Financial Disclosure. LASIK Flap Parameters IntraLase Microkeratome 6/9/2008. Femtosecond LASIK Flaps: What Could We Customize Yesterday?

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1 Financial Disclosure Arturo Chayet, MD Tijuana, BC Mexico Perry S. Binder, MS, MD San Diego CA USA I have the following financial interests or relationships to disclose: AMO/IntraLase Corporation - C Acufocus - Travel Outcomes Analysis Software, Inc O Allergan, Inc. C UV X Partcipating Consultant Ophthonix, Inc. - C LASIK Flap Parameters IntraLase Microkeratome Hinge Location N, S, T N,S Hinge Width Software, Degrees Keratometry Dependent Flap Diameter Software Controlled Keratometry Dependent Flap Thickness Software Controlled Low SD Pachymetry & Blade Dependent; High SD Flap Shape Planar Meniscus (Schwind, Lasitome Planar) Side Cut Angle Software controlled, Degrees 28 degrees Femtosecond LASIK Flaps: What Could We Customize Yesterday? Flap Diameter Flap Side Cut Angle Degrees Hinge Location Nasal, Superior, Temporal Hinge Angle 30 to 90 Degrees Flap Depth Flap Centration Flap Creation Speed 17 to 25 Seconds/9mm diameter Laser spot and line separation 8 x 8 um Laser spot energy 0.9 to 1.2 uj Why Should We Customize LASIK Flaps? Limiting Corneal Diameters Unusual Orbital Configurations Eliminate/Control Risk of Hinge Ablation w Certain Laser Algorithms Interface Epithelial Ingrowth LASIK Dry Eye Symptoms Nerve Regeneration Flap Slippage/Stability Long Term Side Cut Wound Healing Predict or Eliminate Induced HOA RMS Improve Ease of Flap Lift IntraLase 5 th Generation Laser 2008 High rep rate, 5 th generation femtosecond laser (IntraLase technology). 150 khz Flap customization capabilities, including elliptical shape, unique sidecut architecture shapes Lower energy and faster flap creation - 8 to 12 sec. for 9 mm flap w 8 x 8 um Spot & line 1

2 IntraLase 5 th Generation Laser 2008 Allows Bevel-In Sidecut Angle Innovative new industrial design - hi-res video microscope - touch screen user interface - digital video output High Repetition Rate Faster procedure time Flaps created in less than 10 secs depending on S/L separation Lesser chance of suction break affecting outcomes Increased patient throughput Patient comfort w less suction time Allows use of low energy for less tissue response/inflammation smoother stromal bed surfaces Allows use of tight spot separation for easy lifts IntraLase Generations 4 th Generation 5 th Generation Hinge Location N, S, T N,S, T Hinge Width Software, Degrees Software, Degrees Round vs. Elliptical Flaps Round: Invades peripheral vital lamellar fibers Elliptical: Preserves peripheral vital lamellar fibers Flap Diameter Software Controlled Software Controlled Flap Thickness Software Controlled Low SD Software Controlled Low SD Flap Shape Planar Planar, Elliptical Side Cut Angle Software controlled, Degrees Software controlled, Degrees 9 mm Flap Time Sec. w 8 x 8 S/L Sec. w 8 x 8 S/L Raster Energy uj uj Right Eye: Round Flap with a Superior vs Elliptical with a Temporal Hinge Elliptical Flap Symmetrical distribution of forces to the elliptical cornea Prevents resection of the vital peripheral corneal fibers that contribute greatly to the biomechanical strength of the cornea Moves the hinge peripherally to maximize stromal bed exposure for full delivery of excimer ablation Allows use of wider hinge angle for greater flap stability and preservation of corneal nerves 2

3 Elliptical flap OS Temporal Hinge Kerry Assil, MD Contralateral feasibility study Performed on 20 eyes using calibration adjustment Vertical diameter = 9.0mm Horizontal diameter = 7% larger Temporal hinge 60º hinge angle Round flap Hinge will undergo ablation S T OS Temporal Hinge OS Temporal Hinge Decrease hinge to 45º Avoids hinge ablation But smaller hinge reduces flap stability S T Or one can create an elliptical flap and increase horizontal treatment diameter as well as avoid hinge ablation Larger hinge angle for improved flap stability Less dry eye? S T Flap Induced Change in Manifest Refraction and Aberration: Elliptical vs Circular Conclusion: Statistically significant differences in Defocus Higher Order RMS Wavefront Error Spherical Aberration (SA) (Subset of Higher Order Errors) All differences in aberrations are less than 0.22 µm for both the elliptical and circular flap groups No clinically relevant statistically significant differences in flap stability, visual outcomes, or optical aberrations when the flap shape is slightly elliptical Sidecut Angle J Marshall: bevel in side cut angle provides the best biomechanical strength in penetrating keratoplasty A Chayet. Data on file, AMO, Inc. 3

4 J Marshall & K Meeks Inverted Bevel In Side Cut Angle Provides better wound healing for biomechanical stability of the post LASIK cornea Easier to reposition the flap Prevents flap slippage intraoperatively No gutter or flap edge gap Theoretical benefits Resists Trauma Further Reduced Risk of Epithelial Ingrowth Control Induced HOA RMS Results: Rabbit Study (M. Knorz, MD) 70 degree 5 th Generation FS laser flaps had more than 2x the strength of the MK flaps 140 degree 5 th Generation FS laser flaps had more than 3x the strength of the MK flaps Measurement of Flap Tensile Strength Human Study A. Chayet, MD Patients suitable for myopic LASIK Prospective, Randomized, Contralateral 1 eye 70º, 1 eye 150º sidecut angle Flaps created, relifted 10 weeks later w excimer ablation Graded flap lift ease; side cut angle masked to surgeon FLAP LIFT at 10 WEEKS 70 Degree Bevel 150 Degree Bevel Evaluation of Flap Adhesion: Initial Clinical Experience with ifs laser % of eyes Greater Flap Adhesion Strength at 10 Weeks with Inverted 150 Bevel-In Side Cut 5% 64% 31% N=30 0 Less Resistance More Resistance No Difference P Binder, A Chayet. Presented ASCRS

5 Evaluation of Flap Adhesion: Initial Clinical Experience with ifs laser Discussion: Gutter was noticeably less Flap Creation Possibility of less epithelial in-growth on primary and secondary procedures Supports earlier findings of both Marshall and Knorz May reduce incidence of flap slippage in addition to oval flap and wider hinge width Preserves the contribution of Bowman s Membrane to the strength of the post-lasik cornea P Binder, A Chayet. Presented ASCRS Clinical Studies (A. Chayet, MD) Study to Optimize Parameters : A total of 38 Patients (76 eyes) Included 26 Contra lateral Mate Pairs (26 Round, 26 Oval Flaps) Flap Thickness: 90 (N=43) or 100 (N=33) um Diameter: 8.0 to 9.0 mm Ovality : 7 to 9%; Temporal Hinge 45 or 55 degrees Round Flaps: Superior Hinge, 45 or 55 degrees Side Cut Angle: 70 degrees Raster Energy: 0.38 to 0.79 uj 5x5 S/L N=9; 6x6 S/L N=43 7x7 S/L N= 8; 8x8 N= 6 Time for 9 mm flap was 10 for 8 x8 and for 7 x 7 Optimization Study (All Eyes) OVAL ROUND Att d No. Eyes Mean Range No. Eyes Mean Range Optimization Study (Contralateral Eyes) OVAL ROUND Att d No. Eyes Mean Range No. Eyes Mean Range Attempted vs. Achieved Percentage of Eyes Reported Cumulative Snellen UCVA (20/) *emmetropic targets only* 1Day (n=73) 1 Week (n=73) 1 Month (n=73) Achieved 7 6 y = x R 2 = y = x R 2 = Attempted Round Oval Round Oval 5

6 Comparison of Stromal Bed Quality of the 5 th Generation ifs and the Ziemer LDV 4 th ifs Laser 5 th ifs Laser ZIEMER LDV Laser M Sarayba, D Durrie, MD. Data on file, AMO, Inc. 9 x 30 x 135 x 300 x Note flap edge profiles LASIK SURGERY GOALS PREDICT WAVEFRONT ABERATIONS PREDICT FLAP THICKNESS TO CONTROL DEPTH OF LASER ABLATION AS WELL AS SAFELY CORRECT MOST REFRACTIVE INDICATIONS ELIMINATE FLAP COMPLICATIONS OPERATE ALL ORBITAL CONFIGURATIONS REDUCE OR ELIMINATE INFLUENCE OF PREOP CORNEAL THICKNESS AND CURVATURE ON FLAP DIMENSIONS IMPROVE FLAP STABILITY REDUCE DRY EYE SYMPTOMS CRATE SMOOTH STROMAL SURFACES PREDICTABLE AND EXCELLENT VISUAL AND REFRACTIVE OUTCOMES 5 TH Generation ifs Laser Accomplishes most of these ideal goals better than any currently existing technology while placing all the tools necessary for customizing the flap within the hands of the surgeon - Increased Speed to Permit Tight Spot/Line Separation - Inverted Side Cut Bevel Strengthens Wound - Elliptical Dimensions Permit Safety with Additional Potential Clinical Benefits lasiksupport@aol.com 6