Aberration-Free Refractive Surgery

Refractive surgeons and clinicians are searching for a more customized approach to refractive surgery. This comprehensive report on sight correction through laser surgery provides the practitioner with solid background information from top industry researchers. Carefully illustrated, it details the latest techniques and clinical results in wavefront technology for laser surgery, which is now defining a new standard of practice. This second edition has been significantly expanded to include in-depth descriptions of important new advances as well as glimpses of what the future holds. The book will be indispensable to all wishing to extend their knowledge of customized refractive surgery with an understanding of the underpinning technology.

1 The Development of Wavefront Technology and its Application to Ophthalmology.- 1.1 Abstract.- 1.2 Introduction.- 1.3 History.- 1.4 Principle of Aberration Measurement.- 1.5 Definitions of Optical Imaging Quality.- 1.5.1 Root Mean Square.- 1.5.2 Optical Aberration Index.- 1.5.3 Modulation Transfer function.- 1.5.4 Point Spread function.- 1.5.5 Application of the Performance Indices in a Normal Human Eye.- 1.6 Principle of Closed Loop Adaptive Optical Control.- 1.6.1 Adaptive Optics in Astronomy.- 1.6.2 History of Adaptive Optics at the University of Heidelberg.- 1.6.3 Performance of Foil Mirrors.- 1.6.4 Comparison of Foil Mirrors and Microchip Mirror.- 1.7 CLAO/Bille Aberrometer.- 1.8 Demonstration of CLAO/Bille Aberrometer.- 1.9 Conclusion.- References.- 2 Wavefront Technology for Vision and Ophthalmology.- 2.1 Introduction.- 2.2 Wavefront Optometers.- 2.3 Ray-Tracing Optometers.- 2.4 Wavefront-Sensing Optometer.- 2.5 Equivalency of Subjective Ray Tracing and Outgoing Wavefront Sensing.- 2.6 Vision Diagnosis Using Wavefront Optometers.- 2.7 Aberrations of the Human Eye.- 2.8 Determination of Best Sphero-Cylindrical Correction by Wavefront Optometers.- 2.9 Point-Spread Function (PSF) of the Eye.- 2.10 Modulation Transfer Function (MTF) of the Eye.- 2.11 Wavefront-Guided Vision Correction.- 2.12 Customized Vision Correction through Adaptive Optics.- 2.13 Wavefront Technology for Laser Vision Correction.- 2.14 Wavefront Technology for the Calibration of Excimer Refractive Lasers.- 2.15 High-Resolution Retinal Imaging with Adaptive Optics.- 2.16 Photoreceptor Images.- 2.17 Confocal Scanning Laser Ophthalmoscopes (cSLO).- 2.18 Conclusion.- References.- 3 An Aberration Generator for the Calibration of Wavefront-Sensing Optometers.- 3.1 Introduction.- 3.2 Dynamic Source of Seidel Aberrations.- 3.3 Phase Plates as Sources of Aberrations.- 3.4 Experimental Setup with the Wavefront Sensor.- 3.5 Experiment Results.- 3.6 Conclusions.- References.- Appendix: Wavefront Maps of 8 Phase Plates.- 4 Optical Quality of the Human Eye: The Quest for Perfect Vision.- 4.1 Introduction.- 4.2 The Quality of the Human Eye.- 4.3 Linear Systems.- 4.3.1 Optical Systems.- 4.4 Representation of Aberrations.- 4.5 Simulations.- References.- 5 First Clinical Results with WaveScan.- 5.1 First Clinical Results with WaveScan.- 5.2 The Performance of a Wavefront Measurement and the Understanding of the WavePrint Maps.- 5.3 Application of the WaveScan in Refractive Surgery.- 5.4 Results of this Study: The Reliability of the WaveScan Compared to Manifest Refraction.- 5.5 Final Review.- 6 Wavefront Analysis: Clinical Primer.- 6.1 Definition of Important Terms.- 6.2 Current Ocular Refraction Evaluation Systems.- 6.2.1 Phoroptor and Autorefractors.- 6.2.2 Corneal Topography.- 6.2.3 20/10 Perfect Vision Wavefront System.- 6.2.4 Other Wavefront Sensing Devices.- 6.3 How the VISX 20/10 Wavefront System Works.- 6.4 How to Read a Wavefront Map.- 6.5 What are the Shortcomings of Shack-Hartmann Wavefront Analysis?.- 6.6 Reproducibility and Effect of Pupil Size.- 6.7 Clinical Examples.- 6.7.1 Case 1. Keratoconus.- 6.7.2 Case 2. Status Post Radial Keratotomy.- 6.7.3 Case 3. Posterior Subcapsular Cataract and Anterior Cortical Cataract.- 6.7.4 Case 4. Status Post Penetrating Keratoplasty for Keratoconus.- 6.7.5 Case 5. Unoperated "Normal" Eyes.- 6.7.6 Case 6. Irregular LASIK Ablation.- 6.7.7 Case 7. Status Post Hyperopic LASIK.- 6.7.8 Case 8. Normal Examination / No Refractive Error.- 6.7.9 Case 9. Status Post Myopic LASIK.- 6.7.10 Case 10. Normal Examination / Minimal Refractive Error.- References.- 7 Active Eye Tracking for Excimer Laser Refractive Surgery.- 7.1 Introduction.- 7.2 Understanding the Nature of Eye Motions during LVC.- 7.3 Effects of Head Movements on Fixation.- 7.4 Quality of the Fixation Target.- 7.5 Fixation Target Recommendations.- 7.6 Tracker Speed Requirements.- 7.7 Eye Tracking Methods: Analog vs. Video.- 7.8 Video Techniques.- 7.9 Sampling Rate and Tracking Rate.- 7.10 VISX Eye Tracking System.- 7.11 Robustness and Safety Features.- 7.12 Ablation Accuracy of the VISX ActiveTrak System.- 7.13 Conclusion.- References.- 8 Cyclotorsional Eye Tracking.- 8.1 Introduction.- 8.2 Tracking Algorithm.- 8.3 Affine Parameter Estimation.- 8.4 Torsional Tracking Results.- 8.5 Combined Torsional Alignment and Tracking Results.- 8.6 Algorithm Verification.- 8.7 Clinical Results.- 8.8 Real-Time Implementation.- 8.9 Conclusions.- References.- 9 Full Registration of the Laser Ablation to the Wavefront Measurement.- 9.1 Introduction.- 9.1.1 System Design and Calibration.- 9.1.2 WaveScan Instrument.- 9.1.3 Laser System.- 9.2 Image Processing.- 9.3 Biological Changes Leading to Registration Errors.- 9.3.1 Changing Position of the Pupil Center.- 9.3.2 Cyclorotation.- 9.4 Conclusion.- References.- 10 Variable Spot Scanning and Wavefront-Guided Laser Vision Correction.- 10.1 The VSS Approach to Ablation.- 10.2 Advantages of VSS.- 10.3 Predictive Ablation Modeling.- 10.4 Ablation Geometry.- 10.5 How the VSS Algorithm Solves the Ablation Problem.- 10.6 Accuracy of VSS.- 10.7 Physical Validation of VSS.- 10.8 Conclusion.- References.- Appendix A: Theory and Practice of Variable Spot Scanning: An Alternative to the Zernike Method for Reconstructing Wavefronts S. Somani.- Appendix B. Theory and Practice of Variable Spot Scanning: Generation of Wavefront-Correcting PreVue Lenses Using Variable Spot Scanning E. Gross.- Appendix C: Theory and Practice of Variable Spot Scanning: Using a Variable Repetition Rate to Reduce VSS Treatment Time E. Gross.- 11 Wavefront Driven Custom Ablation: First Clinical Results.- 11.1 Introduction.- 11.2 History.- 11.3 Methods.- 11.3.1 Wavefronts.- 11.3.2 Single Pass Wavefront Measurement.- 11.3.3 Principle of the Shack-Hartmann Sensor.- 11.3.4 Techniques.- 11.3.5 Presentation of WaveScan Results.- 11.3.6 What a Wavefront Map Can Tell Us.- 11.3.7 What Is the RMS/OAI?.- 11.3.8 Treatment Tables.- 11.4 The Study.- 11.4.1 Scope of Study.- 11.4.2 Study Group.- 11.4.3 Subject Eligibility.- 11.5 Results.- 11.5.1 Uncorrected Visual Acuity.- 11.5.2 Best Corrected Visual Acuity.- 11.5.3 Refractive Error.- 11.5.4 Higher Order Aberrations.- 11.6 Conclusion.- References.- 12 Photorefractive Keratectomy: Indications, Surgical Techniques, Complications, and Results.- 12.1 Introduction.- 12.2 Indications for PRK.- 12.3 Preoperative Management.- 12.4 Surgical Technique.- 12.5 Preoperative Medications.- 12.6 Epithelial Removal.- 12.6.1 Mechanical.- 12.6.2 Chemical.- 12.6.3 LASEK.- 12.6.4 Laser.- 12.6.5 Transepithelial.- 12.6.6 Stromal Treatment.- 12.7 Nomogram and Laser Algorithm.- 12.7.1 Centration.- 12.7.2 Stromal Cooling.- 12.8 Postoperative Management.- 12.8.1 Medications.- 12.8.2 Epithelial Healing.- 12.9 Complications.- 12.9.1 Haloes and Glare.- 12.9.2 Loss of Visual Performance.- 12.10 Late Complications.- 12.10.1 Undercorrection.- 12.10.2 Overcorrection.- 12.10.3 Haze and Regression.- 12.10.4 Treatment of Haze and Regression.- 12.10.5 Decentration.- 12.10.6 Irrecular Astigmatism.- 12.11 Results.- 12.11.1 Myopic PRK.- 12.11.2 Hyperopic PRK.- 12.12 Summary.- 13 Reviewing the Wavefront Clinical Trials: Myopia, Hyperopia, and Eyes with Reduced Acuity.- 13.1 Wavefront-Guided Myopia Treatment Results.- 13.2 Study Description.- 13.3 Patient Satisfaction with Night Vision.- 13.4 Summary.- 13.5 Hyperopia Study.- 13.6 Study Description.- 13.7 Case Study.- 13.8 Reduced Acuity Patients.- 13.9 Case Study.- 13.10 Conclusion.- 14 Refractive Surgical Applications of Femtosecond Lasers.- 14.1 Introduction.- 14.2 Laser-Tissue Interaction.- 14.3 All-Solid-State Femtosecond Laser Technology.- 14.4 Instrumentation.- 14.4.1 Femtosecond Laser Application System for Clinical Use.- 14.4.2 Ophthalmic Femtosecond Laser Procedures.- 14.5 Experimental Results.- 14.6 First Clinical Experience with the FEMTEC Laser.- 14.7 Conclusion and Outlook.- References.- 15 Femtosecond Laser Technology in Keratoplasty.- 15.1 The Cornea - Architecture of an Electromagnetic Interface.- 15.2 Curative Corneal Surgery-Keratoplasty.- 15.3 A Vision for Vision: Fully Integrated Curative Corneal Procedures.- 15.4 Why Quest for Novel Techniques?.- 15.5 Challenges-A Virtual Blade as an Ideal Tool?.- References.- Excursus: A Nomenclature Framework for Quantitative Evaluation of Corneal Femtosecond Laser Procedures.- Case Report.- Comment.- References for Excursus.- Appendices.- A Refractive Society Symposium.- A.1 Comparing WaveScan and Manifest Refractions D.D. Koch.- A.2 Patient Selection for LVC Using Wavefront Technology J.F. Doane.- A.3 Multi-center Wavefront Ablations T.P. O'Brien.- A.4 Six-month U.S. Refractive Wavefront Ablation Results C. Kraff.- A.5 Preliminary Therapeutic Wavefront Ablation Results R.K. Maloney.- A.6 Presbyobic LASIK Techniques G.E. Tamayo.- A.7 Diagnostic Wavefront Compensation with Adaptive Optics F.H. Loesel.- B Refractive Outcomes with "One-Step" Wavefront Guided LASIK D.D. Koch, L. Wang.- B.1 Introduction.- B.2 Patients and Methods.- B.2.1 Patient Selection.- B.2.2 WaveScan Treatment Design.- B.2.3 WavePrint Treatment Methods.- B.2.4 Main Outcome Measures.- B.3 Results.- B.3.1 Cohort Description.- B.3.2 UCVA.- B.3.3 Change in BSCVA.- B.3.4 Predictability.- B.3.5 Stability.- B.3.6 Higher Order Aberration Changes.- B.3.7 Complications and Adverse Events.- B.4 Conclusion.- About the Editors.