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Mastering the Techniques of LASIK, EPILASIK and LASEK (Techniques and Technology)
Ashok Garg, Bojan Pajic, Jorge L Alio, Cyres K Mehta
SECTION ONE: PREOPERATIVE EVALUATION AND MACHINES DYNAMICS
1:
Fundamentals in Corneal Topography
INTRODUCTION TO CORNEAL TOPOGRAPHY
Corneal Shape
Corneal Topography Technology: Evolution
Measurement Procedure
Placido-based Systems
Non Placido-based Systems
ANALYSIS OF THE CORNEAL TOPOGRAPHY DATA: CORNEAL MAPS, DESCRIPTORS AND INDEXES
Topographic Displays: Corneal Maps
Color-Coded Scales
Quantitative Descriptors of Corneal Topography: Corneal Indexes
CLINICAL APPLICATIONS OF CORNEAL TOPOGRAPHY
The Assessment of the Refractive Patient
Preoperative Evaluation
Detecting Irregular Astigmatism
Ensuring Refractive and Topographic Stability following Discontinuation of Contact Lens Wear
Ruling out Keratoconus and Other Ectatic Corneal Disorders
Operative Evaluation
Postoperative Evaluation
Normal Topographic Changes after Refractive Surgery
Postradial Keratotomy (RK)
Postastigmatic Keratotomy (AK)
Postphotorefractive Keratotomy (PRK)
Postlaser In Situ Keratomileusis (LASIK)
Postlaser Thermal Keratoplasty (LTK)
Abnormal Topographic Patterns after Refractive Surgery: Complications
Preoperative and Postoperative Assessment of Intrastromal Corneal Rings
The Assessment of the Corneal Astigmatism after Keratoplasty
Applications in Cataract Surgery
Evaluation of Irregular Astigmatism
Diagnosis of Surface and Ectatic Diseases
Keratoconus
Pellucid Marginal Degeneration
Keratoglobus
Terrien's Marginal Degeneration
Pterygium
Contact Lens Fitting
Evaluation of Tear Film Quality
BIBLIOGRAPHY
2:
Principles of Scanning Lasers for Customized LASIK
INTRODUCTION
Engineering and Clinical Correlation
TECHNOLOGY SUMMARY
LASIK PRINCIPLES
Single-Zone Method
Multizone Method
High-Order Formulas in LASIK
Aspherical Profile
MICROKERATOME TECHNOLOGY
LASIK SYSTEM
The Advantages of Scanning Laser
Efficient Beam Delivery
Compact, Low Cost, and Reliable
Smooth Surface Ablation
Customized Ablation Patterns
Minimal Surface Aberration (SA)
Other Clinical Advantages
Optimal Scanning Parameters
Positive Cylinder Correction
Compound (Toric) Error
WAVEFRONT TECHNOLOGY
Zernike Analysis for Different Devices
SHAPE FACTOR ANALYSIS
CUSTOMIZED CORRECTION
Topography-Guided LASIK
Limitations of CCR
BIBLIOGRAPHY
3:
Orbscan Corneal Mapping in Refractive Surgery
INTRODUCTION
Orbscan Corneal Mapping for Refractive Surgery Diagnostics
Selection Criteria
Power Maps
Posterior Elevation
Pachymetry
Composite/Integrated Information
4:
Advances in Microkeratomes
INTRODUCTION
EVOLUTION
BARRAQUER APPLANATION TONOMETER (FIG. 4.1)
Basic Mechanism of Microkeratome
MECHANICAL MICROKERATOMES
SKBM-Summit-Krumeich-Barraquer-Microkeratome (Fig. 4.2)
Moria M2
STEPS FOR ASSURING ACCURATE APPLANATION AND PROPER SUCTION
AMADEUS (ALLERGAN)
MK–2000
Hansatome Microkeratome (Bausch and Lomb)
Power Supply
CENTURION SES MICROKERATOME–PLANAR MICROKERATOME
SET UP
Introduction
The Bdk –3000 /Bection –Deckinson K-300 (Insight Technologies)
Keratome Head
Suction Ring
Blade
Hand Piece
Power Unit and Vacuum
NON-MECHANICAL MICROKERATOMES
The So Called Bladeless Lasik
Introduction
The Water Jet Microkeratome: Bladeless Microkeratome
Types
MEDIJET
VISIJET
Differences in Design
FEMTOSECOND LASER
NEW DISPOSABLE MICROKERATOMES
CONCLUSION
5:
Femtosecond Laser for Corneal Flaps
INTRODUCTION
Methods and Patients
Confocal Corneal Laser-Microscopy
Slit-Scanning Techniques
Laser-Scanning Microscopy and Pachymetry
Results
Discussion
6:
Rotational Eyetracker System, Its Importance and Clinical Outcomes
INTRODUCTION
DESCRIPTION OF THE IMPLEMENTED IRIS RECOGNITION TECHNOLOGY
Clinical Evidence for the Need of Rotational Tracking
Published Literature
Own Datas of Cyclotorsional Measurements with B and L's Rotational Tracker
Technical Background of B and L's HEYE TECH Iris Pattern Recognition
Design of the Iris Pattern Recognition Tool
IMPLEMENTATION INTO THE PLATFORM
Therapeutic Module (H.EYE.TECH)
General Functionality of the Eyetracker System
Lateral Eye Tracker System
Rotational Eye Tracker System
ACKNOWLEDGEMENTS
7:
Posterior Corneal Changes in Refractive Surgery
INTRODUCTION
TOPOGRAPHY
ORBSCAN
PRIMARY POSTERIOR CORNEAL ELEVATION
Posterior Corneal Topography
Preexisting Posterior Corneal Abnormalities
Agarwal Criteria to Diagnose Primary Posterior Corneal Elevation
IATROGENIC KERATECTASIA
EFFECT OF POSTERIOR CORNEAL CHANGE ON IOL CALCULATION
8:
Pre-Lasik Retina Examination and Its Clinical Relevance
CONCLUSION
9:
Pre-Laser Assisted Stromal In situ Keratomileusis [LASIK] Investigation of Dry Eye
10:
Dry Eye as Informed Consent Prior to Refractive Surgery
INTRODUCTION
Evaluation
Management
Communication and Informed Consent
SECTION TWO: LASIK, EPILASIK AND LASEK SURGICAL TECHNIQUES
11:
Aberropia: A New Refractive Entity
INTRODUCTION
Materials and Methods
Results
Discussion
CONCLUSION
12:
LASIK—Indications and Surgical Steps
13:
Corneal Wavefront Guided Lasik
TOPOGRAPHY AND WAVEFRONTS
Methods
Advantages of ORK CORWAVE (ORK-W)
Steps in Performing a Corneal Wavefront Guided Ablation
OUR EXPERIENCE
CASE STUDY
POSTOPERATIVE WAVEFRONT (FIG. 13.4)
COMPARATIVE VISUAL ACUITY SIMULATIONS (FIG. 13.5)
LET's TAKE A LOOK AT ANOTHER CASE
CONCLUSION
FURTHER READING
14:
Zyoptix
INTRODUCTION
ABERRATIONS
ZYOPTIX LASER
ORBSCAN
ABERROMETER
ZYLINK
Results
DISCUSSION
CONCLUSION
15:
Topography Assisted LASIK
INTRODUCTION
HOW DOES TA-LASIK WORK?
CASE REPORTS
Patient CW: Irregular Astigmatism after Penetrating Injury
Patient AT: Decentered Ablation after PRK
Patient DK: Irregular Astigmatism after PKP and RK
Patient ASJ: Asymmetric WTR-Astigmatism
PATIENTS AND RESULTS
SUMMARY
16:
Bifocal Profiles and Strategies of Presbyopic-LASIK
INTRODUCTION
TWO-STEP STRATEGY
COMPARISON OF ABLATION PROFILES
CENTRAL ABLATION DEPTHS
BIFOCAL PROFILES (CM AND PM)
DISCUSSION
CONCLUSION
APPENDIX
17:
Presbyopic Multifocal LASIK (PML): A New Approach in Corneal Refractive Surgery
APPROACHES TO THE SURGICAL CORRECTION OF PRESBYOPIA
The PML™ Procedure
Results
Pearls and Lessons Learned
18:
Hormone Treatment and Refractive Surgery
19:
Presby-LASIK in Pseudophakic Eyes with the Wavelight Allegretto
INTRODUCTION
Patients and Methods
Results
DISCUSSION
CONCLUSION
20:
Wavefront Aberrometry for Irregular Astigmatism
INTRODUCTION TO WAVEFRONT ABERRATION
CORNEAL WAVEFRONT ABERRATIONS
CORNEAL WAVEFRONT AS A GUIDE FOR THE CORRECTION OF IRREGULAR ASTIGMATISM
Basis of Treatment
Clinical Examination
Surgical Technique
Results
Efficacy
Safety
Predictability
Higher Order Aberrations
Total Higher Order Corneal Wavefront
First Order Aberrations
Coma-like Aberrations
Spherical-like aberration
CASE REPORT
CONCLUSIONS
21:
Hyperopic Lasik for Accommodative Esotropia
TREATMENTS FOR ACCOMMODATIVE ESOTROPIA
Preoperative Examination
SURGICAL TECHNIQUE
RESULTS
Refraction
Topography
Visual Acuity
Primary Position
Sensory Tests
Complications
DISCUSSION
CONCLUSION
22:
Wide Zone Lasik for Hyperopia
INTRODUCTION AND BRIEF HISTORY
WIDE ZONE VS CONVENTIONAL (NARROW ZONE) HYPEROPIC LASIK
SURGICAL TECHNIQUE
FUTURE ADVANCES
SUMMARY
23:
Topographic and Aberrometer Guided Laser
INTRODUCTION
Aberrations
Zyoptix Laser
Orbscan
Aberrometer
ZYLINK
RESULTS
DISCUSSION
CONCLUSION
24:
Presbyopic LASIK
INTRODUCTION
PREVIOUS EXCIMER LASER TECHNIQUES
History
Principle
PROLATE AND OBLATE CORNEA
TECHNIQUE
KERATOMETRY AND PACHYMETRY
Astigmatism
Plano Examples
Example 1
Hyperopic Examples
Example 2
Example 3
Myopic Example
Example 4
SUMMARY
25:
Corneal Wavefront LASIK after Penetrating Keratoplasty
TIMING OF LASIK AFTER KERATOPLASTY
Technique
CASE STUDY
IN CONCLUSION
26:
IOL Power Calculations after Corneal Refractive Surgery
STRATEGIES TO BE USED WHEN PRIOR DATA IS AVAILABLE
The History Method1
Example
Calculations
Example
Calculations
The DBR Method2
Example
Example
Using Corneal Topography3
The Double K Method4
Theoretical Formula 20046
Modified Keratometry Method3
Corrected Keratometry7
Back Calculated IOL Power8
Example
Example
Nomogram Based Adjustment of IOL Power11
Example
Corrected Refractive Index Method12
STRATEGIES TO BE USED WHEN PRIOR DATA IS NOT AVAILABLE
Corneal Topography13
The Hard Contact Lens Method15
Example
Regression Derived Clinical Method17
Example
Intraoperative Retinoscopy18
The Gaussian Optics Formula21
Theoretical Variable Refractive Index Method22
27:
Comparison of Methods for IOL Power Calculation after Incisional and Photoablative Refractive Surgery
CORNEAL POWER AFTER KERATOREFRACTIVE SURGERY
Change of Corneal Asphericity
Change of Ratio between Anterior and Posterior Corneal Surfaces
Theory
Gullstrand's Schematic Eye
The Real Eye
Keratometric Refractive Index after Laser Ablative Refractive Surgery
The Effective Lens Position: Another Source of Error
Intraocular Lens Power Calculation after Refractive Corneal Surgery
Empirical Method
Clinical History Methods
Contact Lens Method
Topographic Data
Consideration of Posterior Corneal Curvature
Method based on Correlation between Axial Eye Length and Corneal Radius Correcting Factor
Method based on Correlation between Axial Eye Length and a Theoretical Variable Keratometric Refractive Index
Method based on Correlation between Actual Corneal Curvature and Corneal Power Correcting Factor
Modifying the Final Value of the IOL as a Function of the SIRC
Refraction-derived Method
Aphakic Intraoperative Refraction Techniques
The Camellin-Calossi Formula
(a) Incisional Refractive Surgery
(b) Laser Ablative Refractive Surgery
Clinical Data
28:
Epi-LASIK: An Advanced Surface Ablation Procedure
INTRODUCTION
Epi-LASIK: An Evolving Technique
Histological Findings of Mechanically Separated Epithelial Sheets
Epi-LASIK: The Surgical Procedure
Postoperative Treatment
Early Postoperative Course
Clinical Results
CONCLUSIONS
29:
Excimer Laser Subepithelial Ablation (ELSA) or LASEK Offers Return to Surface Ablation
CONCLUSIONS
30:
Tear Film Function, Ocular Surface Integrity and Corneal Sensation After Laser-Assisted Subepithelial Keratectomy
INTRODUCTION
Tear Film Function and Ocular Surface Integrity
Corneal Sensation
CONCLUSIONS
31:
LASEK (Laser Assisted Subepithelial Keratectomy)
WHY IS LASIK LOOSING ITS GLORY?
LASEK Gains Popularity
Surgical Considerations
LASEK with Mitomycin C
Follow-Up
Disadvantages of LASEK
Postoperative Pain
Buttonholing
Blurred Vision
Corneal Haze
LASEK in Relation to PRK and Epi-LASIK
BIBLIOGRAPHY
32:
A New Suction Trephine for LASEK
33:
Ocular Pharmacokinetics in LASIK and LASEK Surgery
FURTHER READING
SECTION THREE: COMPLICATIONS AND THEIR MANAGEMENT
34:
LASIK Complications and Management
MICROKERATOME COMPLICATIONS
Free Cap
Incomplete Flap
Thin Flaps, Buttonholes and Irregular Cuts
Epithelial Defects
Corneal Bleeding
Corneal Perforation
LASER COMPLICATIONS
Decentered Ablation
Central Islands
POSTOPERATIVE COMPLICATIONS
Flap Folds and Wrinkles
Flap Loss
Interface Debris
Sands of the Sahara Syndrome
Epithelial Ingrowth
Infection
Dry Eye
Regression, Undercorrection and Overcorrection
Corneal Ectasia
Retinal Complications
35:
A New Algorithm for Controlling Corneal Asphericity in LASIK
INTRODUCTION
ASPHERICAL PROFILE
COMPARING WITH MEASUREMENTS
PREDICTION OF CORNEAL ASPHERICITY
Example # 1
Example # 2
CENTRAL ABLATION DEPTH
EFFECTIVE ZONE SIZE
SURFACE ABERRATION
APPLICATIONS
Application # 1
Application # 2
Application # 3
Application # 4
DISCUSSIONS
CONCLUSION
APPENDIX
THE LINS's N=2/3 POWER FACTOR
36:
Critical Issues Affecting LASIK Outcomes
INTRODUCTION
Laser System and Parameters
Microkeratome
ABLATION ALGORITHMS
High-order Term
Aberration Rate Calibration
Optimized Transition Zone (OTZ)
Corneal Asphericity Change
Q-Factor Customized Ablation
CONCLUSION
BIBLIOGRAPHY
37:
Management of LASIK and LASEK Complications (Interesting Cases)
CORNEAL HAZE AFTER LASEK WITH MITOMYCIN
History
Operation Done
Complication
Management
Discussion
Corneal Haze
FLAP WRINKLES
History
Operation Done
Complication
Management
Discussion
FREE FLAP
History
Operation Done
Complication Faced
Management of Complication
The Tricky Part of the Management is
Discussion
38:
Corneal Ectasia Post LASIK: The Orbscan Advantage
INTRODUCTION
CORNEAL ECTASIA
SELECTION CRITERIA
PACHYMETRY5
POSTERIOR ELEVATION MAP (FIG. 38.4)
POWER MAP
COMPOSITE/INTEGRATED INFORMATION
FUTURE THOUGHTS
ACKNOWLEDGEMENTS
39:
LASIK and Dry Eyes
EFFECT OF LASIK ON CORNEAL SENSATION
MANAGEMENT OF DRY EYE AFTER LASIK
40:
Management of the Dry Eye (Ocular Surface Syndrome=OSS) after Refractive Surgery
INTRODUCTION
Complications in Refractive Surgery
The Tear Film
The “Dry Eye” or the Ocular Surface Syndrome (OSS)
The Cyclic Disorder by Lemp4
The Ocular Surface Syndrome (OSS)
BASIC SCIENCES IN OSS
Corneal Innervation and the Ocular Surface Syndrome (OSS)
Surface Properties of the Normal and the Damaged Corneal Epithelium
Pre-surgical Examinations for Determination of Eventual OSS Problems in the Prospective Refractive Surgery Patient
Tear Stability Tests
Tear Volume Tests
Invasive Tests
Noninvasive Tests
Other Tests
Impression Cytology
Corneal Topography in Combination with Confocal Biomicroscopy
Management of the Ocular Surface Syndrome
Blepharitis
Frequency and Composition of Evaluation and Management Visits for OSS
Mild Induced OSS
Moderate OSS
Severe OSS
In More Detail
Artificial Tears
Oral Antioxidants
Punctal Occlusion
Other Treatment Alternatives
PRIMUN NON NOCERE
41:
LASIK Hinge Location and Dry Eye
CONCLUSION
SECTION FOUR: RECENT ADVANCES AND FUTURE PROSPECTS
42:
ReLASIK (LASIK Enhancement)
INTRODUCTION
Factors Associated to LASIK Enhancements
INDICATIONS
EVALUATION
Pachymetry
Topography
TIMMING
CONTRAINDICATIONS
REOPERATION TECHNIQUE
Second Cut
Relifting the Flap
SURGICAL TECHNIQUE
COMPLICATIONS
Outcomes After Laser in situ Keratomileusis Retreatment
SUMMARY
43:
Solid-state Lasers for Refractive Surgery
INTRODUCTION
Katana, Solid-state UV Laser for Refractive Surgery Since 2003
Clinical Experience
Solid-state Lasers vs Excimer Lasers
CONCLUSION
44:
Corneal Biomechanics—Customization
45:
Thermal Keratoplasty for Hyperopic Correction using a Focused Diode Laser
INTRODUCTION
HYPEROPIA CORRECTION (TABLE 45.2)
PENETRATION DEPTH
TEMPERATURE PROFILE
SAFETY AND EFFICACY
CONCLUSION
46:
Recent Update on Lasik Techniques
I. FEMTOSECOND LASER
II. PATTERN OF ELEVATED, IRREGULAR ASTIGMATISM AND ABERRATION HIGHER ORDER AFTER PERFORMING A LAMELLAR KERATOTOMY WITH AN AMADEUS SIS KERATOM IN KERATOPLASTY EYES
Aim
Patients and Methods
Results
CONCLUSION
III. ROTATIONAL EYETRACKER SYSTEM
IV. ASPHERIC ABLATION ALGORITHMS
V. WAVEFRONT DRIVEN PROCEDURES WITHOUT PHARMACOLOGICAL PUPIL DILATION
VI. OPTICAL COHERENCE TOMOGRAPHY— INTEGRATED ONLINE PACHYMETRY (OCP)
CONCLUSION
ACKNOWLEDGEMENTS
INDEX
TOC
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