Keratoconus: A Comprehensive Guide to Diagnosis and Treatment

Preface
Treatment of Keratoconus
Contents
Contributors
Part I: Keratoconus Diagnosis
Clinical Presentation and Evolution of Keratoconus
1 Introduction
2 Classification
3 Prevalence
4 Etiology
5 Risk Factors
6 Ocular and Systemic Diseases
7 Sex
8 Ocular Symptoms
9 Clinical Signs
10 Progression
11 Conclusion
References
Natural Progression of Keratoconus
1 Introduction
2 Corneal Curvature Measures
3 Thinnest Pachymetry Measurement
4 Visual Acuity and Refraction
References
Prospective Biomarkers in Keratoconus
1 Relationship Between Ocular Allergy and Keratoconus
2 Matrix Metalloproteinases
2.1 Relationship Between Contact Lens Wear or Eye Friction and Altered Expression of Matrix Metalloproteinases in Keratoconus Patients
2.2 Potential Mechanistic Linkages Between Risk Factors and Matrix Metalloproteinase–Mediated Corneal Weakening (Alterations of Extracellular Matrix Breakdown Components and Matrix Metalloproteinases in Keratoconus)
2.3 Clinical Implications: Use of Contact and Scleral Lenses, Topical and Systemic Drugs, and Cross-Linking
2.4 Test Implications: Expression of Matrix Metalloproteinases in the Tears of Keratoconus Carriers
3 Evaluation of Galectin-1 and Galectin-3 as Potential Biomarkers in Keratoconus
4 Conclusion and Perspective
References
The Role of Thyroid Gland Dysfunction in the Development of Keratoconus
1 Thyroid Hormones and Keratoconus Pathophysiology
2 Thyroid Hormones and Corneal Structure
3 Thyroid Hormones in Keratoconus Patients
3.1 Tears
3.2 Human Aqueous Humor
3.3 Blood
4 Thyroid Hormone Changes During Pregnancy
5 Thyroidectomy and Progression of Keratoconus
6 Final Considerations
References
Eye Rubbing and Keratoconus
1 Introduction
2 Atopy and Keratoconus
3 Pathogenesis of Keratoconus Related to Eye Rubbing
4 Eye Rubbing in Normal Corneas
5 Eye Rubbing in Keratoconus
6 Association Between Eye Rubbing and Keratoconus
7 No Association Between Eye Rubbing and Keratoconus
8 Measuring the Mechanical Trauma of Eye Rubbing
9 Conclusion
References
Early Diagnosis of Keratoconus: When Should One Suspect It?
1 Introduction
2 Anamnesis and Initial Approach
3 Topography
4 Pachymetry
5 Corneal Tomography
6 Elevation Maps
7 Belin/Ambrósio Display
8 Holladay 6 Maps Display
9 Automated Detection Program for Subclinical Keratoconus
10 Diagnosis
11 Other Forms of Diagnosis
11.1 Segmental Corneal Tomography
11.2 Optical Coherence Corneal Tomography
11.3 Corneal Biomechanics
11.4 Confocal Microscopy
References
Algorithms and Other Tools for Keratoconus Diagnosis
References
Corneal Topography for Keratoconus Diagnosis
1 Introduction
2 Normal and Abnormal Corneal Topography
3 Indices for Assessing Irregularities in the Corneal Surface
3.1 Univariate Quantitative Detection Systems
3.1.1 Simulated Keratometry
3.1.2 Central Keratometry
3.1.3 Inferior–Superior Value
3.1.4 Skew of the Steepest Radial Axis
3.1.5 Surface Asymmetry Index
3.1.6 Surface Regularity Index
3.1.7 Irregular Astigmatism Index
3.1.8 Analyzed Area
3.1.9 Different Sector Index
3.1.10 Opposite Industry Index
3.1.11 Center Surround Index
3.1.12 Index of Surface Variance
3.1.13 Index of Vertical Asymmetry
3.1.14 Keratoconus Index
3.1.15 Center Keratoconus Index
3.1.16 Index of Height Asymmetry
3.1.17 Index of Height Decentration
3.1.18 Smallest Radius of Sagittal Corneal Curvature
3.1.19 Cone Location and Magnitude Index
3.2 Multivariate Quantitative Detection Systems
3.2.1 KISA% Index
3.2.2 Keratoconus Severity Index
3.2.3 Klyce/Maeda Keratoconus Index
3.2.4 Keratoconus Prediction Index
3.2.5 Smolek/Klyce Neural Network
3.2.6 Rabinowitz/McDonnell Index
References
Pentacam for Keratoconus Diagnosis
1 Pentacam
2 Keratoconus Screening
3 Refractive Maps Display
3.1 Anterior Axial Curvature Map
3.2 Pachymetric Map
3.3 Elevation Maps (Best-Fit Sphere)
4 Topometric Indices/Topometric Keratoconus Staging Display
4.1 Inferior–Superior Ratio Described by Rabinowitz and McDonnell
4.2 KISA%, Described by Rabinowitz and Rasheed
4.3 Height Decentration Index
4.4 Index of Vertical Asymmetry
5 Belin/Ambrósio Display
6 Belin ABCD Keratoconus Staging and Progression Display
7 Holladay Report
8 Corneal Ring Display
9 Considerations
References
Galilei™ for Keratoconus Diagnosis
1 Keratoectasias
2 Diagnosis of Keratoconus
2.1 Prekeratoconus Stages
2.2 Keratoconus Signs and Indices: Ectasia
2.2.1 Steepening of Maximum Keratometry
2.2.2 Extreme Peripheral Flattening of the Anterior Surface
2.2.3 Increased Asphericity and Negative Total Corneal Spherical Aberration
2.2.4 Height of Central Ectasia Assessed with the Best-Fit Sphere Maximum Elevation
2.3 Keratoconus Signs and Indices: Asymmetry
2.3.1 Indices of Asymmetry from the Anterior Curvature
2.3.2 Cone Location and Magnitude Index-X
2.3.3 Indices of Asymmetry from the Elevation Best-Fit Toric Asphere Maps
2.3.4 Asymmetry of the Wave Front: Coma, Trefoil, and Tetrafoil
2.4 Keratoconus Signs and Indices: Central Thinning and Increased Thickness Progression
References
Corneal Biomechanics in Keratoconus Diagnosis
1 Introduction
2 The Ocular Response Analyzer
3 Corneal Visualization Scheimpflug Technology
4 Combination of Data Tomography and Biomechanics
5 Clinical Example
6 Conclusion
References
Corneal Tomography and Biomechanical Integration
1 Introduction
2 Anatomical Influence
3 Biomechanical Changes Related to Age
3.1 Age-Related Corneal Reticulation
4 Importance of Corneal Ectasias
5 Biomechanical Changes in Keratoconus
6 Biomechanics in Ectasia After Refractive Surgery
References
What Is New in Contrast Sensitivity for Keratoconus Diagnosis?
1 Introduction
2 The Contrast Sensitivity Test: An Expanded Concept of Visual Performance
2.1 Visual Acuity and Visual Performance
3 The Contrast Sensitivity Procedure
4 Contrast Sensitivity in Keratoconus
5 Conclusion
Appendix
The Contrast Sensitivity Test: An Expanded Concept from Visual Acuity to Visual Performance
References
How to Follow the Patient After Keratoconus Diagnosis
1 Introduction
2 Ocular Allergy Treatment: Advice Not to Rub the Eye
3 Clinical Approach
3.1 Eyeglasses
3.2 Contact Lenses
3.3 Oral Riboflavin Intake
4 Surgical Approach
4.1 Satisfactory Best Spectacle-Corrected Visual Acuity with High Risk for Progression: Consider Cross-Linking
4.2 Satisfactory Best Spectacle-Corrected Visual Acuity with Low Risk for Progression: Prescription Eyeglasses and/or Contact Lenses, Phakic Intraocular Lenses, and Refractive Lens Exchange
4.3 Unsatisfactory Best Spectacle-Corrected Visual Acuity and/or Contact Lens Intolerance: Consider Intrastromal Corneal Ring Segment Implantation
4.4 Satisfactory Best Spectacle-Corrected Visual Acuity after Intrastromal Corneal Ring Segment Implantation with High Risk for Progression: Consider Cross-Linking
4.5 Unsatisfactory Best Spectacle-Corrected Visual Acuity and/or Contact Lens Intolerance Ineligible for Intrastromal Corneal Ring Segment Implantation
5 Conclusion
References
Assessing Keratoconus Progression
1 Epithelial Map Indices
2 Topographic Indices
3 Tomographic Indices
3.1 Pachymetric Profile
4 Elevation Indices
5 Refractive Parameters
6 ABCD Display
7 Conclusion
References
Controversies in Keratoconus Diagnosis
1 Is It a Cone or Not?
1.1 Demographics
1.2 Bilaterality
1.3 Two-Hit Theory
1.4 Keratoconus and Pellucid Marginal Degeneration
1.5 Against-the-Rule Astigmatism and Pellucid Marginal Degeneration
1.6 Corneal Warpage and Keratoconus
1.7 Eyelid Position and Topographic Data
1.8 Is there Superior Keratoconus?
1.9 Tear Film
1.10 Software Fitting Errors
1.11 Does Allergy Cause Keratoconus?
2 Does Keratoconus Progress or Not?
2.1 Which Parameters Should Be Compared?
2.2 Can Artificial Intelligence Help Us?
2.3 How to Distinguish Measurement Error from Progression
2.4 Is the Treatment Effective?
3 Conclusion
References
Artificial Intelligence in Keratoconus Diagnosis
1 Introduction
2 Machine Learning
3 Machine Learning Categories
4 Deep Learning
5 Artificial Intelligence and Keratoconus
6 Artificial Intelligence and Topography
7 Artificial Intelligence and Tomography
8 Artificial Intelligence and Corneal Biomechanics
9 Artificial Intelligence and Genetics
10 Artificial Intelligence and Intrastromal Corneal Ring Segment Implantation
11 Conclusion
References
Part II: Treatment
Preoperative Evaluation of Keratoconus
1 Peculiarities in Consultation with the Keratoconus Patient
2 The Anamnesis
3 The Ophthalmological Examination
4 Special Exams for Corneal Analysis
5 The Keratoconus Patient Profile
6 The Keratoconus Patient’s Family
7 Guide for Keratoconus Patient Consultation
References
Keratoconus Treatment Flowchart
1 Nonsurgical Procedures
1.1 Contact Lenses
2 Surgical Procedures
2.1 Progression
2.2 Cross-Linking
2.3 Intrastromal Corneal Ring Segments
2.4 Other Procedures
3 Conclusion
References
Drug Therapy in Keratoconus Patients
1 Eye-Rubbing Prevention
1.1 Why Is It Important to Help Patients Avoid Avoid/Reduce Eye Rubbing?
2 Dietary Riboflavin
3 Conclusion
References
Step-by-Step to Perform a Manifest Refraction and Tips for Prescription of Glasses in Keratoconus Patients
References
Contact Lenses in Keratoconus: Possibilities and Flowchart
1 Introduction
2 Choosing the Best Solution
3 The Contact Lens Choice
References
Soft Contact Lenses for Keratoconus: When Are They Indicated?
1 Introduction
2 Spherical and Toric Soft Contact Lenses
3 Soft Contact Lens Wear in the Piggyback System
3.1 Fitting the Soft Contact Lens
3.2 Fitting the Rigid Gas-Permeable Contact Lens
3.3 Advantages of the Piggyback System
3.4 Disadvantages of the Piggyback System
3.5 Relevant Considerations
4 Soft Contact Lenses Designed Specifically for Keratoconus
4.1 Perfect Keratoconus
4.2 Hidroblue UV Ceratogel
4.3 Other Soft Contact Lenses Designed for Keratoconus
4.4 Fitting of Contact Lenses
References
Rigid Gas-Permeable Contact Lens Fitting In Keratoconus
1 Introduction
2 Corneal Keratometry, Topography, and Tomography in Keratoconus
2.1 Keratometry
2.2 Computerized Corneal Topography
2.3 Computerized Corneal Tomography
2.4 Other Methods
3 Classification of Keratoconus
3.1 Classification by Keratometric Readings
3.2 Topographic and Tomographic Classification by Morphologic Shape and Profile
3.2.1 Round or Nipple Cone
3.2.2 Oval or Sagging Cone
3.2.3 Globus Cone
3.2.4 Undefined Cone
4 Corneal Contact Lens Fitting Techniques in Keratoconus
4.1 Apical Clearance
4.2 Apical Bearing
4.3 Three-Point Touch
4.4 Selection of the Rigid Gas-Permeable Contact Lens Diameter, Considering the Cone Location and Shape
5 First Designs of Rigid Gas-Permeable Corneal Lenses for Treatment of Keratoconus
5.1 Monocurve Lenses
5.2 Soper or Bicurve Lenses
5.3 McGuire Lenses
5.4 Ni-Cone Lenses
6 New Lens Designs
6.1 Aspheric Lenses
6.2 Multiaspheric Lenses
7 Some Lens Designs Available in Brazil
7.1 Monocurve (Spheric) Lens)
7.2 Optolentes Laboratory Lenses
7.2.1 The Dupla Face Family of Lenses: Dupla Face and Dupla Face K
7.2.2 The Century Family of Lenses: Century, Century K, and Century Plus
7.3 Mediphacos Laboratory Lenses
7.3.1 The Rose K Family of Lenses: Rose K, Rose K2, Rose K2 IC, and Rose K2 Post Graft
7.4 Solótica Laboratory Lenses
7.4.1 The Best Fit Family of Lenses: Best Fit, Best Fit K, and Best Fit K Max
7.5 Ultralentes Lenses
7.5.1 Aspheric Monocurve Lenses
7.5.2 Ultracone (Double Base Curve) UC
8 Clinical Case Reports
8.1 Case 1: Keratoconus Lens Fitting with Ultracone Lenses
8.2 Case 2: Keratoconus Lens Fitting with Ultracone Lenses
9 Conclusion
References
Piggyback Contact Lenses for Keratoconus
1 Introduction
2 Corneal Oxygenation in the Piggyback System
3 Indications for Use of the Piggyback System
3.1 Intolerance of Corneal Rigid Gas-Permeable Contact Lenses
3.1.1 Stable and Centralized Corneal Rigid Gas-Permeable Contact Lens with a Good Adaptation Pattern on an Intact Cornea in an “Intolerant” (Hypersensitive) Patient
3.1.2 Stable and Centralized Corneal Rigid Gas-Permeable Contact Lens with a Good Adaptation Pattern on a Previously Altered Ocular Surface (with Dry Eye and/or Diffuse Punctate Keratitis)
3.2 Instability of Corneal Rigid Gas-Permeable Contact Lenses
3.2.1 Centralized Corneal Rigid Gas-Permeable Contact Lens that Has a Good Adaptation Pattern but Is Unstable
3.3 Epithelial Erosion in Users of Corneal Rigid Gas-Permeable Contact Lenses
3.3.1 Occasional Corneal Epithelial Erosion
3.3.2 Recurrent Corneal Epithelial Erosion
4 Adaptation of Contact Lenses in the Piggyback System
5 Disadvantages and Complications of the Piggyback System
References
Scleral and Miniscleral Lenses for Patients with Keratoconus
1 Keratoconus
2 Prevalence of Keratoconus
3 History of the Scleral Lens
4 Indications for Scleral Lens Use
5 Lens Classification
6 Scleral Lens Zones
7 Corneoscleral Lenses
8 Miniscleral Lenses
8.1 Thinner Lenses
8.2 Corneal Clearance
8.3 Limbal Clearance
8.4 Advantages of Miniscleral Lenses
8.5 Scleral Toricity
8.6 Complications
9 Scleral Lenses
9.1 Vault Height
9.2 Conjunctival Staining and/or Blanching
10 Fitting of Miniscleral and Scleral Lenses
11 Why Are Scleral and Miniscleral Lenses More Comfortable Contact Lenses?
12 Toricity in Scleral and Miniscleral Lenses
13 Use of Scleral and Miniscleral Lenses in Keratoconus
14 Conclusion
References
What Is New in Contact Lenses for Keratoconus?
1 Introduction
2 Current Technology
3 New Technologies
4 Last Words
References
Contact Lens Fitting After Intrastromal Corneal Ring Segment Implantation
1 Introduction
1.1 Implantation of Two Ring Segments or a Long Arc Ring Segment
1.2 Implantation of a Short Arc Ring Segment
2 Lens Adaptation
2.1 Important Factors in Adaptation After Intrastromal Corneal Ring Segment Implantation
3 Soft Contact Lenses
4 Corneal Rigid Gas-Permeable Lenses
4.1 Multiaspherical Contact Lenses
5 The Piggyback System
6 Scleral Lenses
References
Contact Lens Fitting in Pellucid Marginal Degeneration
1 Introduction
2 Contact Lens Fitting in Pellucid Marginal Degeneration
3 Surgical Options for Pellucid Marginal Degeneration
References
Contact Lens Fitting Following Corneal Graft Surgery
1 Keratoplasty
2 Hydrogel Contact Lenses
3 Hybrid Contact Lenses
4 Rigid Gas-Permeable Contact Lenses
4.1 Corneal Rigid Gas-Permeable Contact Lenses
4.2 Semiscleral Contact Lenses
4.3 Miniscleral and Scleral Contact Lenses
5 The Piggyback System
6 Bandage Contact Lenses
References
Corneal Cross-Linking: Indications and Contraindications
1 Introduction
2 Indications for Cross-Linking
3 Corneal Infections
4 Chemical Burns
5 Bullous Keratopathy and Other Causes of Corneal Edema
6 Combination of Cross-Linking with Other Treatment Modalities
6.1 Cross-Linking Plus Limited Topography-Guided Photorefractive Keratectomy for Progressive Keratoconus
6.2 Cross-Linking After Refractive Surgery
6.3 Cross-Linking Plus Intrastromal Corneal Ring Segment Implantation
7 Cross-Linking for Bleb Leaks
8 Contraindications for Corneal Cross-Linking
8.1 Nonprogressive Keratoconus or Corneal Ectasia
8.2 Pachymetry Thinner than 400 Microns
8.3 Prior Herpetic Ocular Infection
8.4 Severe Dry Eye
8.5 Active Eye Disease
8.6 Systemic Diseases
8.7 Other Contraindications
References
Corneal Collagen Cross-Linking Controversies
1 Introduction
2 Controversies in Pediatric Keratoconus: When Is It Indicated?
3 Oral Riboflavin: Is It Effective?
4 Transepithelial Cross-Linking
5 Accelerated Cross-Linking
6 Pulsed Cross-Linking
7 Conclusion
References
Intrastromal Corneal Ring Segment Implantation and Cross-Linking: When and How?
1 Literature Review
1.1 Two-Stage Surgery
1.2 Should Cross-Linking or Intrastromal Corneal Ring Segment Implantation Be Performed First?
1.3 Single-Stage Surgery (Simultaneous Procedures)
1.4 Single-Stage Versus Two-Stage Surgery
1.5 Other Approaches
2 Changes in Surgical Techniques
3 Postoperative Care and Complications
4 Conclusion
References
Corneal Collagen Cross-Linking Complications: How to Manage Them
1 Introduction
1.1 Types of Cross-Linking Complications
2 Early-Onset Complications
2.1 Pain
2.2 Epithelial Complications
2.3 Infections
2.3.1 Bacterial Keratitis
2.3.2 Viral Keratitis
2.3.3 Fungal Keratitis
2.3.4 Acanthamoeba Keratitis
2.4 Inflammation
2.4.1 Sterile Infiltrates
2.4.2 Corneal Melting
2.4.3 Corneal Edema
2.4.4 Haze
2.4.5 Other Types of Inflammation
2.5 Endothelial Complications
3 Late-Onset Complications
3.1 Vision Loss
3.1.1 Persistent Haze
3.1.2 Corneal Scars
3.2 Biomechanical Failure
3.2.1 Excessive Corneal Flattening
3.2.2 Keratoconus Progression
References
Continued Long-Term Flattening After Corneal Cross-Linking for Keratoconus
References
Corneal Cross-Linking: Standard Versus Accelerated Protocols
1 The Origins of Cross-Linking
2 Advances in Technology
3 Understanding the Photochemistry
4 Reciprocity
5 Oxygen Availability Limits the Acceleration Potential
6 Conclusion
References
Transepithelial Cross-Linking
1 Introduction
2 Effect of Epithelium on Corneal Absorption of Ultraviolet A Radiation and Diffusion of Riboflavin and Oxygen
2.1 Riboflavin
2.2 Ultraviolet A Radiation
2.3 Oxygen
3 Variations of the Transepithelial Technique
4 Clinical Results
5 Conclusion
References
Cross-Linking Ultrathin Corneas
1 Increasing Prevalence
2 Halting Keratoconus Progression
3 Modifications for Thin Cornea Treatment
4 Individualized Cross-Linking for Ultrathin Corneas: The Sub400 Protocol
References
Corneal Cross-Linking for Keratoconus in Children
1 Introduction
2 Cross-Linking for Progressive Keratoconus
3 Cross-Linking Protocols
4 Rationale for Cross-Linking in Pediatric Keratoconus
5 Limitations of Cross-Linking in Children
6 Special Concerns
7 Personal Experience
8 Long-Term Results of Pediatric Cross-Linking
9 Conclusion
References
Corneal Cross-Linking in Down Syndrome Patients
References
History of the Ferrara Ring
References
Indications and Contraindications for Intrastromal Corneal Ring Implantation
1 Indications and Contraindications for Corneal Ring Surgery
2 Objectives of Corneal Ring Surgery
3 Analysis of the Main Objectives of Corneal Ring Surgery
3.1 To Help Slow Down or Prevent Progression of Corneal Ectasia
3.2 To Improve Corrected Vision
4 Indications for Corneal Ring Surgery
5 Legislation and Regularization of Corneal Ring Surgery in Brazil
References
The Ferrara Intrastromal Corneal Ring Segment Nomogram
References
Mediphacos Intrastromal Corneal Ring Segment Nomogram
1 The 2018 Mediphacos Nomogram
2 Type 1 Cone
2.1 Clinical Case 1
3 Type 2 Cone
3.1 Clinical Case 2
4 Type 3 Cone
4.1 Clinical Case 3
5 Type 4 Cone
5.1 Clinical Case 4
6 Type 5 Cone
6.1 Clinical Case 5
7 Study Results
8 Final Considerations
References
Intrastromal Corneal Ring Segment Implantation Outcomes Using Two Different Manufacturers’ Nomograms for Keratoconus Surgery
1 Comparison Between Nomograms
2 Conclusion
References
Refractive and Visual Outcomes After Implantation of Intacs and Other Intrastromal Corneal Ring Segments, According to the Literature
1 Introduction
2 Application of Intrastromal Corneal Rings in Humans
3 Myopia Correction
4 Hyperopia Correction
5 New Technologies and the Role of Intrastromal Corneal Ring Segments
6 The Geometry of the Rings and the Cornea
7 Clinical Results in Keratoconus
8 Conclusion
References
Surgical Planning for Intrastromal Corneal Ring Implantation: An Easy and Objective Way
1 Conclusion
References
Intrastromal Corneal Ring Types
1 Intracorneal Ring Types
2 Keraring
3 Ferrara Ring
4 Intacs
5 Bisantis
6 MyoRing
7 Cornealrings
References
Long-Arc Intrastromal Corneal Ring Segments
1 Comments
References
Asymmetric Intrastromal Corneal Ring Segments
1 Introduction
2 Mechanism of Action
2.1 Progressive-Thickness Intrastromal Corneal Ring Segment Design
3 Surgical Planning
4 Surgical Procedure
4.1 Femtosecond Laser–Assisted Tunnel Creation
4.2 Marking the Planned Axis and Ring Positioning
4.3 Performing the Incision
4.4 Checking the Planned Ring Positioning
5 Efficacy
5.1 Case Example
6 Complications
References
New Designs of Asymmetric Corneal Rings
1 The 160° Asymmetric Ring
1.1 How to Choose the Right Ring
1.2 Summary of 160 AS Ring Choices
2 The 140° Asymmetric Ring
3 Complete Asymmetric Rings
3.1 The ASDL Complete Lateral Asymmetric Ring
3.2 The ASDI Complete Lower Asymmetric Ring
4 The 180° Asymmetric Ring
References
Ferrara HM: A New Intrastromal Corneal Ring Segment Used in Combination with Photorefractive Keratectomy to Correct Moderate to High Myopia
1 Introduction
2 Clinical Study
2.1 Photorefractive Keratectomy Nomogram
3 Surgical Technique
3.1 Intrastromal Corneal Ring Segment Implantation Using the Femtosecond Laser Technique
3.2 Photorefractive Keratectomy
4 Results
5 Comments
References
The Manual Technique for Intrastromal Corneal Ring Segment Implantation: Golden Tips
1 Introduction
2 Preparing the Patient
3 Marking the Central Point
4 Marking the Cornea
5 Making the Corneal Incision
6 Creating the Stromal Pocket
7 Creating an Intrastromal Tunnel
8 Placing the Segment
9 Checking the Final Position of the Segments
References
Femtosecond Laser–Assisted Surgery: Peculiarities of the Different Types of Femtosecond Lasers
1 Introduction
2 Ideal Attributes of a Femtosecond Laser Platform
3 Commercially Available Femtosecond Lasers
3.1 The IntraLase Femtosecond Laser
3.1.1 Docking of the IntraLase
3.1.2 Advantages and Disadvantages of the IntraLase
3.2 The VisuMax Femtosecond Laser
3.2.1 Docking of the VisuMax
3.2.2 Advantages and Disadvantages of the VisuMax
3.3 The WaveLight FS200 Femtosecond Laser
3.3.1 Docking of the WaveLight
3.3.2 Advantages and Disadvantages of the WaveLight
3.4 The LenSx Femtosecond Laser
3.4.1 Docking of the LenSx
3.4.2 Advantages and Disadvantages of the LenSx
3.5 The Femto LDV Femtosecond Laser
3.5.1 Advantages and Disadvantages of the Femto LDV
4 Conclusion
References
Intrastromal Corneal Ring Segment Implantation After Corneal Graft Surgery
1 Introduction
2 Treatment Options to Correct Irregular Astigmatism After Deep Anterior Lamellar Keratoplasty or Penetrating Keratoplasty
3 Nomograms for Intrastromal Corneal Ring Segment Implantation After Deep Anterior Lamellar Keratoplasty or Penetrating Keratoplasty
4 Clinical Outcomes of Intrastromal Corneal Ring Segment Implantation After Deep Anterior Lamellar Keratoplasty or Penetrating Keratoplasty
5 Manual Versus Femtosecond Laser Techniques
6 Comments
7 Conclusion
References
Postkeratoplasty Astigmatism Treatment with a Combination of Intrastromal Corneal Ring Segment Implantation and Photorefractive Keratectomy
1 Introduction
2 Methods
2.1 The First Surgical Procedure (Intrastromal Corneal Ring Segment Implantation)
2.2 Surgical Planning Before Photorefractive Keratectomy
2.3 The Tomography-Assisted Safety Ablation Protocol
2.4 The Second Surgical Procedure (Photorefractive Keratectomy)
2.5 Statistical Analysis
3 Results
3.1 Study Periods
3.2 Tomography-Assisted Safety Ablation Protocol and Follow-Up
3.3 Visual Acuity
3.4 The Spherical Equivalent and Nominal Astigmatism
3.5 Endothelial Density
3.6 Postoperative Complications
4 Case Report
5 Discussion
6 Conclusion
References
Intrastromal Corneal Ring Segment Implantation and Cross-Linking for Treatment of Post–Refractive Surgery Ectasia
1 Iatrogenic Corneal Ectasia
2 Treatment Options
2.1 Corrective Lenses
2.2 Corneal Transplantation
2.3 Corneal Collagen Cross-Linking
2.4 Intrastromal Corneal Ring Segment Implantation
2.4.1 Intacs
2.4.2 Ferrara Ring and Keraring
2.4.3 Nomograms
3 Personal Approach
4 Stop Ectasia with Cross-Linking
5 Remodeling with Intrastromal Corneal Ring Segment Implants
5.1 Choosing the Number, Length, and Thickness of Intrastromal Corneal Ring Segments
5.2 Intrastromal Corneal Ring Segment Positioning and the Incision Site and Depth
6 Conclusion
References
Intrastromal Corneal Ring Implantation in Pellucid Marginal Degeneration
1 Introduction
2 Intrastromal Corneal Rings
3 Ferrara Ring Nomogram for Pellucid Marginal Degeneration and Pellucid-Like Keratoconus
4 Conclusion
References
Intrastromal Corneal Ring Segment Implantation in Children with Keratoconus
References
Intrastromal Corneal Ring Segment Implantation for Early Keratoconus
1 Introduction
2 Therapeutic Options for Early Keratoconus
2.1 Use of Ferrara-Type Intrastromal Corneal Ring Segments in Early Keratoconus
3 Take-Home Message
References
Intrastromal Corneal Ring Segment Implantation for Refractive and Visual Outcomes
1 Introduction
2 Characteristics of Intrastromal Corneal Ring Segment Implants
3 Intrastromal Corneal Ring Segment Use for Refractive Purpose
4 So, Today, What Are the Indications for Intrastromal Corneal Ring Segment Implantation?
4.1 Keratometry
4.2 Refraction Criteria
5 What Is the Best Type of Intrastromal Corneal Ring Segment to Implant in Early Keratoconus?
6 What Is the Future of Intrastromal Corneal Ring Segment Implants? The Ferrara High Myopia Ring!
7 Conclusion
References
Intrastromal Corneal Ring Segment Implantation for Advanced Keratoconus
1 Introduction
2 Treatment Options for Advanced Keratoconus
3 Main Indications for Use of a 320° Intrastromal Corneal Ring Segment in Advanced Cones
3.1 Nipple-Type Keratoconus
3.2 Astigmatic-Type Keratoconus
3.3 Oval-Type Keratoconus
4 Case Example
5 Conclusion
References
Extreme Corneal Remodeling Using Intrastromal Corneal Ring Segments
1 Case 1: “The Third Time’s the Charm” (the Cuddling Technique—Simultaneous Three-Segment Implantation)
2 Case 2: The “Wonderbra” Technique
3 Case 3: “A Little to Four”
4 Discussion
References
Intrastromal Corneal Rings and Photorefractive Keratectomy
1 Intrastromal Corneal Rings and Photorefractive Keratectomy
2 Combined Procedures
3 Complications
4 Conclusion
References
Intrastromal Rings and Phakic Lenses
1 Introduction
2 Technical Considerations
3 Study Results
4 Conclusion
References
Association of Keratoconus Treatment and Phacoemulsification
1 Introduction
2 Treatment Examples
3 Conclusion
References
Intrastromal Corneal Ring Segments and Toric Intraocular Lenses
1 Introduction
2 Intrastromal Corneal Ring Segment Evaluation
3 Biometry and Surgical Technique
3.1 Keratometry Readings
3.2 Axial Length and Intraocular Lens Power Calculation Formulas
3.3 Toric Intraocular Lens Calculation Formulas
3.4 Surgical Plan
4 Conclusion
References
Intraocular Lens Power Calculation in Eyes with Keratoconus and Intrastromal Corneal Ring Segments
References
Complications in Intrastromal Corneal Ring Segment Implantation
References
Refractive Lens Exchange with Small-Aperture Intraocular Implants for Keratoconus
1 Introduction
2 Overview of Pinhole Implants
2.1 The IC-8 Intraocular Lens
2.2 The XtraFocus Implant
3 Background
4 Patient Selection
5 Intraocular Lens Power Calculation
5.1 Combination of a Toric Intraocular Lens and a Pinhole Implant
6 Surgical Technique
7 Adverse Events
7.1 Halos
7.2 Darkening Sensation
8 Important Considerations
8.1 Patient and Surgeon Expectations
8.2 Cataract Surgery and Keratoconus
9 Conclusion
References
Advanced Surface Ablation in Mild Keratoconus
1 Introduction
2 Case Report
2.1 Case Report
2.2 Discussion
3 Conclusion
References
Redefining Forme Fruste Keratoconus
1 Introduction
2 Terminology for Ectatic Corneal Diseases: Forme Fruste
3 Diagnostic Tools
3.1 Corneal Topography
3.2 Corneal Tomography
3.3 Segmental or Layered Tomography
3.4 Corneal Biomechanical Assessment
3.5 Ocular Wave Front Analysis
4 Clinical Examples
4.1 Case 1: Very Asymmetric Ectasia with Forme Fruste Keratoconus
4.2 Case 2: Unilateral Ectasia
4.3 Case 3: Bilateral Forme Fruste Keratoconus
5 Conclusion
References
Indications and Contraindications for Corneal Transplantation in Keratoconus
1 Indications for Deep Anterior Lamellar Keratoplasty
1.1 Intolerance of Contact Lens Wear
1.2 Contraindications for Intrastromal Corneal Ring Segment Implantation
1.3 Complications After Cross-Linking
2 Contraindications for Deep Anterior Lamellar Keratoplasty
References
Deep Anterior Lamellar Keratoplasty: Manual Techniques
1 Manual Technique (Layer by Layer)
2 Big-Bubble Technique
3 Melles Technique
4 Pachy-Bubble Technique
5 Visco Bubble Technique
References
Deep Anterior Lamellar Keratoplasty: How Can We Achieve Bubble Formation in All Cases?
References
Deep Anterior Lamellar Keratoplasty Assisted by a Femtosecond Laser
1 Introduction
2 Femtosecond Laser
3 Femtosecond Incisions
4 Deep Anterior Lamellar Keratoplasty Assisted by a Femtosecond Laser
References
How to Deal with a Type 2 Bubble in Deep Anterior Lamellar Keratoplasty
1 Introduction
2 Cleavage Planes in Big Bubbles
3 Peculiarities of Type 1 and 2 Bubbles
4 Risk Factors for Type 2 Bubble Formation
5 Management of a Type 2 Bubble
5.1 Technique 1 (Descemet’s Membrane–Baring Deep Anterior Lamellar Keratoplasty)
5.2 Technique 2 (Microbubble Incision Deep Anterior Lamellar Keratoplasty)
5.3 Technique 3 (Predesmetic Stroma–Baring Deep Anterior Lamellar Keratoplasty)
5.4 Technique 4
References
Deep Anterior Lamellar Keratoplasty: How to Avoid Conversion to Penetrating Keratoplasty
1 Introduction
2 Tips for Avoiding the Need for Conversion to Penetrating Keratoplasty
2.1 Donor Button Preparation
2.2 Host Cornea Preparation
3 Results
4 Conclusion
References
Complications in Deep Anterior Lamellar Keratoplasty
1 Introduction
2 Intraoperative Complications
2.1 Failure to Create a Bubble
2.2 Intra-Descemet or Type 2 Air Bubble
2.3 Double Bubble
2.4 Stromal Emphysema
2.5 Descemet Perforation
2.6 Donor Cornea Preparation
3 Early Postoperative Complications
3.1 Double Anterior Chamber
3.2 Pupillary Block and a Fixed Dilated Pupil Urrets-Zavalia Syndrome
3.3 Residual Stromal Scarring
3.4 Interface Infectious Keratitis
3.5 Descemet Membrane Folds
3.6 Suture-Related Complications
3.7 Toxic Anterior Segment Syndrome
4 Late Postoperative Complications
4.1 Stromal Immune Reactions
4.2 Interface Vascularization
4.3 Endothelial Cell Loss
4.4 Secondary Failure
4.5 Corneal Erosion
5 Conclusion
References
Bowman Layer Transplantation for Keratoconus
1 Introduction
2 Tissue Selection and Graft Preparation
3 Surgical Technique
4 Results
5 Conclusion
References
Current Indications for Penetrating Transplantation in Keratoconus
High Ametropia Post Transplantation and Options for Its Correction
1 Introduction
2 Options for Correction
2.1 Contact Lenses
2.2 Ametropia Correction with a Laser
3 Phakic Lenses
4 Incisional Surgeries
4.1 Arcuate Incisions
4.2 Wedge Resection
5 Topoplasty
6 Intrastromal Corneal Ring Segments
6.1 Intraocular Pinhole
References
Managing Acute Corneal Hydrops in Keratoconus
1 Introduction
2 Descemetoplasty
2.1 Selection of Cases
2.2 Surgical Technique
2.3 Descemetoplasty Results
3 Discussion
4 Conclusion
References
Part III: Advances in Keratoconus Treatment
Femtosecond Laser–Assisted Intrastromal Corneal Lenticule Implantation for Treatment of Advanced Keratoconus
1 Surgical Technique
1.1 Donor Corneal Lenticule Preparation
1.2 Lenticule Implantation
References
Corneal Epithelial Thickness Mapping in Keratoconus
1 Introduction
2 The Normal Corneal Epithelium
3 The Corneal Epithelium in Keratoconus
4 Application of Corneal Epithelial Thickness Mapping in Diagnosis of Keratoconus
5 Application of Corneal Epithelial Thickness Mapping in the Follow-Up of Keratoconus
6 Anterior Segment Optical Coherence Tomography Imaging Modes in Epithelial Thickness Mapping
7 Conclusion
References
Lenticular Intrastromal Keratoplasty for Keratoconus
1 Indications
2 Inclusion and Exclusion Criteria
3 Types of Lenticules
4 The Implantation Procedure
5 Complications
6 The First Clinical Study
7 Conclusion
References
Intrastromal Corneal Ring Segment Combination for Refinement of Ametropia Correction
1 Introduction
2 Surgical Technique
2.1 Ferrara HM Intrastromal Corneal Ring Segment Implantation: The Femtosecond Laser Technique
2.2 Additional Intrastromal Corneal Ring Segment Implantation
3 Clinical Outcomes
3.1 Case 1
3.2 Case 2
3.3 Case 3
4 Comments
5 Conclusion
Reference
Index