Corneal Emergencies

Description

The book provides a comprehensive insight into various corneal emergencies along with their risk factors, causative agents, diagnostic pearls, treatment challenges and management options. It provides essential information on relevant anatomical and physiological aspects in addition to epidemiology and risk factors. Comprising of explanatory flow diagrams, diagnostic and treatment algorithms and high-quality illustrations, this book is written and edited by renowned corneal specialists who have come together to address this complex topic in a simple and effective manner. The book highlights an important aspect of cornea which is relevant for specialists and general ophthalmologists alike and also serves as an important resource for postgraduate students and trainees. It emphasizes on the practical management of corneal emergencies, supplemented with preferred practice patterns and guidelines. Additionally, the book serves as a quick reference for ophthalmic practitioners to adequately manage such cases at the point of first contact. Foreword Preface Preface About the Editors Contents 1: Anatomical, Pathophysiological, and Wound Healing Aspects in Corneal Emergencies 1.1 Introduction 1.2 Anatomical Considerations 1.3 Physiological Considerations 1.3.1 Epithelium 1.3.2 Stroma 1.3.3 Endothelium 1.4 Corneal Wound Healing 1.4.1 Epithelial Healing 1.4.1.1 Cellular Events 1.4.1.2 Molecular Events 1.4.2 Epithelial Wound Healing Response 1.4.2.1 Corneal Abrasion 1.4.2.2 Corneal Ulcer 1.4.2.3 Thermal Burns 1.4.2.4 Stevens–Johnson Syndrome 1.4.2.5 Chemical Injuries 1.4.2.6 Contact Lens Wear 1.4.3 Stromal Wound Healing 1.4.3.1 Cellular Events 1.4.3.2 Molecular Events 1.4.4 Stromal Wound Healing Response 1.4.4.1 Corneal Ulcer 1.4.4.2 Peripheral Ulcerative Keratitis (PUK) 1.4.4.3 Corneal Lacerations 1.4.4.4 Refractive Surgeries 1.4.4.5 Acute Chemical Injuries 1.4.4.6 Advanced Corneal Ectasia 1.4.4.7 Corneal Transplantation 1.4.4.8 Corneal Graft Rejection 1.4.5 Endothelial Wound Healing 1.4.5.1 Cellular Events 1.4.5.2 Molecular Events 1.4.6 Endothelial Wound Healing Response 1.4.6.1 Corneal Perforation 1.4.6.2 Refractive Surgery 1.4.6.3 Contact Lens Associated Corneal Edema 1.4.6.4 Advanced Corneal Ectasia 1.5 Limbus: Anatomical Considerations and Response to Wound Healing 1.5.1 Stevens–Johnson Syndrome 1.5.2 PUK 1.6 Corneal Innervation and Applied Aspects 1.7 Corneal Vascular System 1.8 Conclusion References 2: Epidemiology and Risk Factors 2.1 Introduction 2.2 Minor Corneal Emergencies 2.2.1 Epidemiology 2.2.2 Risk Factors 2.3 Corneal Lacerations and Penetrating Injuries 2.3.1 Epidemiology 2.3.2 Risk Factors 2.4 Microbial Keratitis 2.4.1 Epidemiology 2.4.2 Risk Factors 2.5 Corneal Perforations 2.5.1 Epidemiology 2.5.2 Risk Factors 2.6 Acute Chemical Injuries 2.6.1 Epidemiology 2.6.2 Risk Factors 2.7 Emergencies Associated with Corneal Transplantation 2.7.1 Epidemiology 2.7.2 Risk Factor 2.8 Acute Graft Rejection 2.8.1 Epidemiology 2.8.2 Risk Factor 2.9 Post-surgical Corneal Wound Dehiscence 2.9.1 Epidemiology 2.9.2 Risk Factors 2.10 Contact Lens-Associated Corneal Emergency 2.10.1 Epidemiology 2.10.2 Risk Factor 2.11 Peripheral Ulcerative Keratitis 2.11.1 Epidemiology 2.11.2 Risk Factors 2.12 Emergency in Advanced Corneal Ectasia 2.12.1 Epidemiology 2.12.2 Risk Factor 2.13 Stevens–Johnson Syndrome 2.13.1 Epidemiology 2.13.2 Risk Factor 2.14 Vitamin A Deficiency and Xerophthalmia 2.14.1 Epidemiology 2.14.2 Risk Factors 2.15 Conclusion References 3: Requisites of Cornea Clinic and Casualty Services to Manage Corneal Emergencies 3.1 Introduction 3.2 Clinic Setup 3.2.1 Equipment and Manpower 3.2.2 Consumables 3.2.3 Drugs 3.2.4 Instruments 3.3 Procedures Performed in OPD 3.3.1 Corneal Scraping 3.3.2 Corneal Gluing 3.3.3 Saline Wash in Acute Chemical Injury 3.3.4 Corneal Foreign Body Removal 3.3.5 Corneal Suture Removal 3.4 Conclusion References 4: Diagnostic and Therapeutic Approach in Management of Corneal Emergencies 4.1 Introduction 4.2 History Taking 4.2.1 Assess Systemic Status 4.2.2 Determine the Mechanism of Injury 4.2.3 Symptoms 4.2.4 Medical History 4.2.5 Treatment History 4.3 Clinical Examination 4.3.1 Visual Acuity 4.3.2 Systemic Examination 4.3.3 External Examination 4.3.4 Slit Lamp Examination 4.3.4.1 Lids 4.3.4.2 Conjunctiva 4.3.4.3 Sclera 4.3.4.4 Cornea Epithelium Stroma Descemet Membrane Endothelium 4.3.4.5 Anterior Chamber (AC) 4.3.4.6 Iris 4.3.4.7 Lens 4.3.4.8 Intraocular Pressure (IOP) 4.3.4.9 Fundus 4.4 Diagnostic Approach 4.4.1 Fluorescein Stain 4.4.2 X-Ray 4.4.3 CT-Scan 4.4.4 MRI 4.4.5 B-Scan 4.4.6 Ultrasound Biomicroscopy (UBM) 4.4.7 Anterior Segment OCT (AS-OCT) 4.4.8 In-Vivo Confocal Microscopy (IVCM) 4.4.9 OCT Angiography (OCTA) 4.4.10 Corneal Topography 4.4.11 Microbiology 4.5 Therapeutic Approach 4.5.1 Acute Chemical Injury 4.5.2 Stevens–Johnson Syndrome 4.5.3 Corneal Ulcer 4.5.4 Peripheral Ulcerative Keratitis 4.5.5 Contact Lens-Related Emergencies 4.5.6 Corneal Hydrops 4.5.7 Post-PK Emergencies 4.5.8 Post-refractive Surgery Corneal Emergencies 4.5.9 Corneal Perforation/Laceration 4.6 Conclusion References 5: Minor Corneal Emergencies 5.1 Introduction 5.2 Corneal Abrasions 5.2.1 Aetiology 5.2.2 Clinical Features 5.2.3 Complications 5.2.4 Examination and Investigations 5.2.5 Management 5.3 Corneal Foreign Body 5.3.1 Clinical Features 5.3.2 Complications 5.3.3 Investigations 5.3.4 Management 5.4 Recurrent Corneal Erosions 5.4.1 Aetiology 5.4.2 Aetiological Types 5.4.3 Clinical Features 5.4.4 Management 5.5 Photokeratitis 5.5.1 Aetiology 5.5.2 Clinical Features 5.5.3 Management 5.6 Minor Chemical Injury 5.6.1 Clinical Features 5.6.2 Management 5.7 Corneal Infections 5.7.1 Viral Keratitis 5.7.1.1 Clinical Features 5.7.1.2 Management 5.8 Miscellaneous 5.8.1 Contact Lens-Related Minor Emergencies 5.8.1.1 Risk Factors 5.8.1.2 Clinical Features 5.8.1.3 Investigations 5.8.1.4 Management 5.8.2 Neurotrophic Keratitis 5.8.2.1 Aetiology 5.8.2.2 Clinical Features 5.8.2.3 Management 5.8.3 Exposure Keratopathy 5.8.3.1 Aetiology 5.8.3.2 Clinical Features 5.8.3.3 Management 5.8.4 Ruptured Corneal Bulla 5.8.4.1 Aetiology 5.8.4.2 Clinical Features 5.8.4.3 Management 5.9 Conclusion References 6: Corneal Laceration and Penetrating Injuries 6.1 Epidemiology 6.1.1 Age and Sex 6.1.2 Socioeconomic Background 6.2 Betts Classification and Nomenclature 6.3 History Taking and Clinical Presentation 6.4 Ocular Investigations 6.4.1 Ultrasonography 6.4.2 X-Ray 6.4.3 CT Scan 6.4.4 Special Attention to Be Given to Following Points While Reading Radiograph/CT Scan 6.5 Treatment 6.5.1 Corneal Abrasion 6.5.2 Corneal Laceration Management 6.5.2.1 General Principles 6.5.2.2 Simple Corneal Laceration 6.5.2.3 Simple Full-Thickness Laceration Less Than 2 mm 6.5.2.4 Simple Full-Thickness Laceration More Than 2 mm 6.6 Basic Principles of Corneal Laceration Suturing 6.6.1 Preferred Anaesthesia 6.6.2 Preferred Suture Material 6.6.3 ‘No Touch’ Technique 6.6.4 Astigmatism and Suturing 6.6.5 Suturing Large Wound with Stellate or Branching Pattern 6.7 Complicated Corneal Lacerations 6.7.1 Corneal Laceration with Uveal Incarceration or Prolapse 6.7.2 Corneal Laceration Along with Limbus or Scleral Involvement 6.7.3 Corneal Laceration with Traumatic Cataract 6.7.3.1 Simultaneous Corneal Tear Repair with Cataract Extraction 6.7.4 Corneal Laceration with Endophthalmitis 6.7.5 Treatment of Associated Cyclodialysis 6.8 Postoperative Management 6.9 Management of Astigmatism After Corneal Laceration Repair References 7: Emergencies in Microbial Keratitis 7.1 Introduction 7.2 Incidence 7.3 Aetiology 7.4 Approach to Diagnosis 7.4.1 History 7.4.2 Clinical Examination 7.4.3 Microbiological Evaluation 7.4.4 Response to Treatment 7.4.5 When to Refer? 7.5 Bacterial Keratitis 7.5.1 Diagnostic Differentiators 7.5.1.1 Staphylococci 7.5.1.2 Streptococci 7.5.1.3 Pseudomonas 7.5.2 Management 7.6 HSV Keratitis 7.6.1 Diagnostic Differentiators 7.6.1.1 HSV Epithelial Keratitis 7.6.1.2 Marginal Ulcer of HSV 7.6.1.3 Stromal Keratitis Necrotising Stromal Keratitis Immune Stromal (Interstitial) Keratitis 7.6.1.4 HSV Endotheliitis 7.6.1.5 Neurotrophic Ulcers 7.7 Fungal Keratitis 7.7.1 Diagnostic Differentiators 7.7.2 Treatment 7.8 Acanthamoeba Keratitis 7.8.1 Diagnostic Differentiators 7.8.2 Treatment 7.9 Pythium Keratitis 7.9.1 Diagnostic Differentiators 7.9.2 Diagnosis 7.9.3 Treatment 7.10 Surgical Management 7.11 Corneal Emergencies Associated with Microbial Keratitis and Their Management (Table 7.1) 7.11.1 Penetrating Trauma with/Without Foreign Body 7.11.2 Descemetocele and Corneal Melt or Perforation 7.11.3 Scleritis 7.11.4 Endophthalmitis 7.12 Conclusion References 8: Corneal Perforations 8.1 Introduction 8.2 Pathophysiology of Corneal Perforations 8.3 Clinical History 8.4 Symptoms 8.5 Signs 8.6 Workup 8.7 Causes of Corneal Perforations 8.7.1 Infectious Corneal Perforations 8.7.1.1 Bacterial Keratitis 8.7.1.2 Fungal Keratitis 8.7.1.3 Viral Keratitis 8.7.2 Non-Infectious Corneal Perforations 8.7.2.1 Autoimmune Conditions 8.7.2.2 Ocular Surface Disease 8.7.2.3 Corneal Degenerations or Ectasias 8.8 Management of Corneal Perforations 8.8.1 Non-surgical Treatment 8.8.1.1 Lubricating Treatments Indication Technique 8.8.1.2 Antimicrobials Indication Technique 8.8.1.3 Anti-collagenases Indication Technique 8.8.1.4 Aqueous Suppressants Indication Technique 8.8.1.5 Anti-Inflammatories Indication Technique 8.8.1.6 Bandage Contact Lens 8.8.2 Surgical Treatment 8.8.2.1 Corneal Gluing Indication Technique Outcomes 8.8.2.2 Tenon’s Patch Graft Technique 8.8.2.3 Keratoplasty Indication Technique Outcomes 8.8.2.4 Amniotic Membranes Indication Technique and Outcomes 8.8.2.5 Conjunctival Flaps References 9: Emergencies in Corneal Refractive Surgeries 9.1 Introduction 9.2 Intraoperative Corneal Emergencies 9.2.1 Corneal Emergencies Related to Microkeratome-Flap Creation 9.2.1.1 Incidence 9.2.1.2 Risk Factors 9.2.1.3 Diagnosis 9.2.1.4 Treatment 9.2.1.5 Prevention 9.2.2 Corneal Emergencies Related to Femtosecond-Laser Assisted Flap 9.2.2.1 Suction Loss Incidence Risk Factors Diagnosis Treatment Prevention 9.2.2.2 Vertical Gas Breakthrough Incidence Risk Factors Diagnosis Management Prevention 9.2.2.3 Flap Tears Incidence Risk Factors Diagnosis Treatment Prevention 9.2.3 Corneal Perforation During Excimer Laser Ablation 9.2.3.1 Risk Factors 9.2.3.2 Treatment 9.2.3.3 Prevention 9.2.4 Lenticule Extraction Related Corneal Emergencies 9.2.4.1 Suction Loss Incidence Risk Factors Diagnosis Treatment Prevention 9.2.4.2 Lenticule Mis-Dissection and Cap-Lenticular Adhesion Incidence Risk Factors Diagnosis Treatment Prevention 9.2.5 Corneal Perforation During Intracorneal Ring Segments Implantation 9.2.5.1 Incidence 9.2.5.2 Risk Factors 9.2.5.3 Diagnosis 9.2.5.4 Treatment 9.2.5.5 Prevention 9.2.6 Corneal Emergencies Related to Radial Keratotomy 9.3 Postoperative Corneal Emergencies 9.3.1 Infectious Keratitis 9.3.1.1 Incidence 9.3.1.2 Causative Organisms 9.3.1.3 Risk Factors 9.3.1.4 Diagnosis 9.3.1.5 Treatment 9.3.1.6 Prevention 9.3.2 Rupture or Dehiscence of Radial Keratotomy Incisions 9.3.2.1 Risk Factors 9.3.2.2 Diagnosis 9.3.2.3 Management 9.3.2.4 Prevention 9.3.3 Intracorneal Ring Segment Extrusion and Corneal Melt 9.3.3.1 Incidence 9.3.3.2 Risk Factors 9.3.3.3 Treatment 9.3.3.4 Prevention 9.3.4 Acute Hydrops 9.3.4.1 Risk Factors 9.3.4.2 Diagnosis 9.3.4.3 Management 9.3.4.4 Prevention 9.3.5 Acute Corneal Haze After Photorefractive Keratectomy 9.3.5.1 Risk Factors 9.3.5.2 Diagnosis 9.3.5.3 Treatment 9.3.5.4 Prevention 9.3.6 Flap Macrostriae and Flap Dislocation 9.3.6.1 Incidence 9.3.6.2 Risk Factors 9.3.6.3 Diagnosis 9.3.6.4 Treatment 9.3.6.5 Prevention 9.3.7 Diffuse Lamellar Keratitis 9.3.7.1 Incidence 9.3.7.2 Risk Factors 9.3.7.3 Diagnosis 9.3.7.4 Treatment 9.3.7.5 Prevention 9.3.8 Central Toxic Keratopathy 9.3.8.1 Incidence 9.3.8.2 Diagnosis 9.3.8.3 Treatment 9.3.9 Pressure-Induced Intralamellar Stromal Keratitis 9.3.9.1 Diagnosis 9.3.9.2 Treatment 9.4 Conclusion References 10: Acute Chemical Injuries of the Cornea 10.1 Introduction 10.2 Causative Agents of Ocular Chemical Injury 10.2.1 Classification of Common Agents Responsible for Causing Ocular Chemical Injuries 10.2.1.1 Vesicants 10.2.1.2 Lacrimatory Agents 10.2.1.3 Plant-Based Toxins 10.2.1.4 Other Common Agents Responsible for Ocular Chemical Injuries 10.3 Pathophysiology of a Corrosive Injury 10.3.1 Rise in Intraocular Pressure (IOP) 10.3.2 Inflammatory Process 10.3.3 Fall in the Aqueous Ascorbate Levels 10.4 Clinical History 10.5 Immediate Treatment and Transfer 10.5.1 Treatment at the Injury Site 10.5.2 Treatment in Ophthalmic Emergency 10.5.2.1 Choice of Fluid and Duration of Irrigation 10.5.2.2 Aqueous Humor Replacement 10.6 Clinical Examination and Classification of Chemical Injuries 10.7 Phases of Chemical Injury 10.8 Treatment 10.8.1 Acute and Early Reparative Treatment 10.8.1.1 Broad-Spectrum Topical Antibiotics 10.8.1.2 Artificial Lubricants and Cycloplegics 10.8.1.3 Oral and Topical Sodium Ascorbate (10%) 10.8.1.4 Corticosteroids 10.8.1.5 Oral Tetracyclines and Topical Citrate 10.8.1.6 Ocular Hypotensive Agents 10.8.1.7 Blood Derived Topical Agents 10.8.2 Surgical Treatment in the Acute Phase 10.8.2.1 Amniotic Membrane Transplantation (AMT) 10.8.2.2 Tenonplasty 10.8.2.3 Glued-On Contact Lens 10.8.3 Treatment in the Intermediate Stage 10.8.4 Chronic Sequelae and Treatment 10.8.4.1 Limbal Stem Cell Transplant 10.8.4.2 Keratoplasty 10.8.5 Treatment of the End-Stage Disease 10.8.5.1 Keratoprosthesis 10.8.5.2 Enucleation or Evisceration 10.8.6 Experimental Treatment Modalities References 11: Emergencies Associated with Corneal Transplantation 11.1 Intraoperative Emergencies 11.1.1 Host Related 11.1.1.1 Posterior Capsule Tear With or Without Vitreous Loss Presentation and Diagnosis Management 11.1.1.2 Suprachoroidal. Hemorrhage Presentation and Diagnosis Management Prevention 11.1.1.3 Descemet Membrane Perforation Incidence and Risk Factors Presentation Management Outcome and Prevention 11.1.2 Donor Related 11.2 Postoperative Emergencies 11.2.1 Complications Common to all Keratoplasties 11.2.1.1 Anterior Segment Inflammation Risk Factors Types Management 11.2.1.2 Wound Leak 11.2.1.3 Glaucoma Presentation Management 11.2.1.4 Suture Related Complications 11.2.1.5 Persistent Epithelial Defect Risk Factors Management Outcome 11.2.1.6 Posterior Segment-Related Complications Endophthalmitis Causative Organism Risk Factors Presentation and Diagnosis Management Prevention Choroidal Detachment Retinal Detachment Cystoid Macular Edema 11.2.1.7 Graft Infection Risk Factors Management Outcome 11.2.1.8 Graft Rejection Incidence Risk Factors Types Management Outcome 11.2.1.9 Graft Failure Management 11.2.2 Complications Specific to Lamellar Keratoplasties 11.2.2.1 Interface-Related Problems Interface Fluid Interface Bleed Interface Infection Epithelial Ingrowth 11.2.2.2 Graft Detachment 11.3 Conclusion References 12: Acute Graft Rejection 12.1 Introduction 12.2 Incidence 12.3 Risk Factors for Corneal Graft Rejection 12.3.1 Donor Characteristics 12.3.2 Host Characteristics 12.3.2.1 Host Bed Vascularisation 12.3.2.2 Failed Grafts 12.3.2.3 Pre-Existing Disease 12.3.3 Technical Factors 12.3.4 Other Factors 12.3.5 Low Risk Penetrating Keratoplasty 12.4 Pathogenesis 12.5 Clinical Presentation 12.5.1 Symptoms 12.5.2 Signs 12.5.2.1 Epithelial Rejection 12.5.2.2 Subepithelial Rejection 12.5.2.3 Stromal Rejection 12.5.2.4 Endothelial Rejection 12.5.3 Differential Diagnosis 12.6 Treatment 12.6.1 Response to Treatment 12.7 Prophylaxis 12.8 Prevention 12.9 Summary References 13: Post-Surgical Corneal Wound Dehiscence 13.1 Introduction 13.2 Corneal Wound Healing 13.3 Wound Dehiscence Following Corneal Surgeries 13.3.1 Penetrating Keratoplasty 13.3.1.1 Clinical Features 13.3.1.2 Types of Graft Dehiscence 13.3.1.3 Predisposing Factors 13.3.1.4 Management 13.3.1.5 Outcomes 13.3.2 Lamellar Keratoplasty 13.3.3 Repaired Corneal Perforation 13.3.3.1 Management 13.3.4 Cataract Surgery 13.3.4.1 Predisposing Factors and Preventive Measures 13.3.4.2 Management 13.3.5 Refractive Surgery 13.3.5.1 Risk Factors and Preventive Measures 13.3.5.2 Management 13.4 Conclusion References 14: Contact Lens-Associated Emergencies 14.1 Introduction 14.2 Pathogenesis of Contact Lens-Related Emergencies 14.2.1 Hypoxia 14.2.2 Mechanical Factors 14.2.3 Immunological Factors 14.2.4 Tear Film Abnormality 14.3 Classification 14.4 Contact Lens Associated Microbial Keratitis 14.4.1 Acanthamoeba Keratitis 14.4.2 Pseudomonas Keratitis 14.4.3 Fungal Keratitis 14.5 Corneal Edema 14.6 Contact Lens-Related Peripheral Ulcer (CLPU) 14.7 Contact Lens Adhesion Phenomenon or Binding 14.7.1 Pathogenesis 14.7.2 Clinical Features 14.7.3 Treatment 14.8 Sterile Corneal Infiltrates 14.9 Contact Lens-Induced Acute Red Eye-CLARE 14.9.1 Clinical Features 14.9.2 Treatment 14.10 Corneal Abrasions 14.11 Conclusion References 15: Peripheral Ulcerative Keratitis 15.1 Introduction 15.2 Clinical Presentation 15.2.1 Symptoms 15.2.2 Clinical Features 15.3 Etiology and Pathogenesis 15.3.1 Etiology 15.3.1.1 Mooren’s Ulcer 15.3.1.2 Collagen Vascular Diseases 15.3.1.3 Infectious Causes 15.3.2 Pathogenesis 15.3.2.1 Immune Complexes 15.3.2.2 Matrix Metalloproteinases (MMP) 15.4 Management 15.4.1 Medical Management 15.4.1.1 Infectious Causes 15.4.1.2 Mooren’s Ulcer 15.4.1.3 With Associated Systemic Disease 15.4.2 Surgical Management 15.4.2.1 Conjunctival Resection with Tissue Adhesive and Bandage Contact Lens Application 15.4.2.2 Management of Perforations