- •Retinal Vein Occlusions
- •Preface
- •Acknowledgments
- •Contents
- •1.1 Anatomy and Histology
- •1.2 Microanatomy of the Retina
- •1.3 Vascular Anatomy
- •Bernoulli’s Principle and Deductions Concerning Changes in Central Retinal Vein Diameter at the Lamina Cribrosa
- •1.4 Pathologic Anatomy
- •1.4.1 Abnormalities of the Vessel Wall
- •1.4.2 Branch Retinal Vein Occlusion
- •1.4.3 Central Retinal Vein Occlusion
- •1.4.4 Hemicentral Retinal Vein Occlusion
- •1.5 Summary of Key Points
- •References
- •2.1 Abnormalities of the Blood
- •2.1.1 Thrombosis
- •2.1.2 Viscosity of Blood
- •2.2 Abnormalities of Blood Flow
- •2.2.1 Retinal Vascular Hemodynamics
- •2.2.1.1 Laplace’s Law
- •2.2.1.2 Poiseuille’s Law
- •A Misapplication of Poiseuille’s Law
- •2.2.1.3 Hemodynamics of Central Retinal Vein Occlusion
- •How Severe Must Central Venous Obstruction Be to Produce Symptoms?
- •The Central Retinal Artery in Central Retinal Vein Occlusion
- •2.2.1.4 Hemodynamics of BRVO
- •2.3 Macular Edema
- •2.3.1 Macular Anatomy and Its Relationship to Macular Edema in Retinal Vein Occlusion
- •2.3.2 Starling’s Law
- •2.3.3 The Retinal Pigment Epithelial Pump
- •2.3.4 Molecular Signaling in Macular Edema
- •Relevant Molecular Biologic Terminology
- •2.3.4.1 Vascular Endothelial Growth Factor
- •2.3.4.2 Other Retinal Cytokines with Lesser Roles
- •2.3.4.3 Molecular Signaling in BRVO
- •2.3.4.4 Molecular Signaling in CRVO
- •What Does the Response of RVO to Intravitreal Anti-VEGF Drugs Say About Pathophysiology?
- •2.4 Retinal Neovascularization
- •Spontaneous Venous Pulsations and CRVO
- •2.7 Animal Models of Retinal Vein Occlusion
- •2.7.1 Animal Models of BRVO
- •2.7.2 Animal Models of CRVO
- •2.8 Summary of Key Points
- •2.9 Future Directions
- •References
- •3.1 Background for Clinical Genetics
- •3.2 The Role of Polymorphisms in Genetic Studies
- •3.3 Types of Genetic Study Design
- •Why Are So Many Association Studies for Retinal Vein Occlusion Negative?
- •3.4 Studies of the Genetics of Retinal Vein Occlusion
- •3.4.1 Platelet Glycoprotein Receptor Genes
- •3.4.2.1 Pooled Retinal Vein Occlusion
- •3.4.2.2 Central Retinal Vein Occlusion
- •3.4.2.3 Branch Retinal Vein Occlusion
- •3.4.4 202210G > A Mutation of the Prothrombin Gene (Factor II Leiden)
- •3.4.6 Protein C
- •3.4.7 Protein S
- •3.4.8 Fibrinogen
- •3.4.9 Factor XII
- •3.4.12 Other Negative Genetic Association Studies
- •3.5 Summary of Key Points
- •References
- •4.1 Nosology of Retinal Vein Occlusions
- •4.2 Branch Retinal Vein Occlusion
- •4.3 Central Retinal Vein Occlusion
- •Central Retinal Vein Occlusion with Nonischemic and Ischemic Hemispheres
- •4.3.1 Conversion from Nonischemic to Ischemic Forms of Retinal Vein Occlusion
- •4.4 Summary of Key Points
- •References
- •Quantifying Risk
- •The Major Epidemiologic Studies of Retinal Vein Occlusion
- •5.2 Prevalence
- •5.2.1 Pooled Retinal Vein Occlusion
- •5.2.2 Branch Retinal Vein Occlusion
- •5.2.3 Central Retinal Vein Occlusion
- •5.2.4 Hemicentral Retinal Vein Occlusion
- •5.3 Incidence
- •5.3.1 Pooled Retinal Vein Occlusion
- •5.3.2 Branch Retinal Vein Occlusion
- •5.3.3 Central Retinal Vein Occlusion
- •5.4 Risk and Protective Factors for Retinal Vein Occlusion
- •5.4.1.1 Pooled Retinal Vein Occlusion
- •5.4.1.2 Branch Retinal Vein Occlusion
- •5.4.1.3 Central Retinal Vein Occlusion
- •5.4.1.4 Hemicentral Retinal Vein Occlusion
- •5.4.2 Gender
- •5.4.2.1 Pooled Retinal Vein Occlusion
- •5.4.2.2 Branch Retinal Vein Occlusion
- •5.4.2.3 CRVO
- •5.4.2.4 Hemicentral Retinal Vein Occlusions
- •5.4.3 Race
- •5.4.4 Laterality
- •5.4.5 Body Mass Index
- •5.4.6 Education
- •5.4.7 Physical Activity
- •5.4.8 Miscellaneous Factors Explored and Not Found Important
- •5.5.1 Pooled Retinal Vein Occlusion
- •5.5.2 Branch Retinal Vein Occlusion
- •5.5.3 Central Retinal Vein Occlusion
- •5.5.4 Hemicentral Retinal Vein Occlusion
- •5.6 Life Expectancy
- •5.7 Visual Impact of Retinal Vein Occlusions
- •5.8 Summary of Key Points
- •References
- •6.1 Introduction
- •6.2 Systemic Associations
- •6.2.1 Hypertension
- •6.2.1.1 Pooled Retinal Vein Occlusions
- •6.2.1.2 Branch Retinal Vein Occlusion
- •6.2.1.3 Central Retinal Vein Occlusion
- •6.2.2 Diabetes Mellitus
- •6.2.2.1 Pooled Retinal Vein Occlusion
- •6.2.2.2 Branch Retinal Vein Occlusion
- •6.2.2.3 Central Retinal Vein Occlusion
- •6.2.3 Hyperlipidemia
- •6.2.3.1 Pooled Retinal Vein Occlusions
- •6.2.3.2 Branch Retinal Vein Occlusion
- •6.2.3.3 Central Retinal Vein Occlusion
- •6.2.4 Cardiovascular Disease
- •6.2.4.1 Pooled Retinal Vein Occlusion
- •6.2.4.2 Branch Retinal Vein Occlusion
- •6.2.4.3 Central and Hemicentral Retinal Vein Occlusion
- •6.2.4.4 Stroke
- •6.2.4.5 Carotid Artery Disease and Peripheral Vascular Disease
- •6.2.5 Rheologic and Hematologic Abnormalities
- •6.2.6 Coagulation Abnormalities
- •6.2.6.1 Antiphospholipid Antibodies
- •6.2.6.2 Factor VII
- •6.2.6.3 Factor VIII
- •6.2.6.4 Lipoprotein a
- •6.2.6.5 Von Willebrand Factor
- •6.2.6.6 Other Coagulation Factors
- •6.2.7 Hyperhomocysteinemia
- •6.2.7.1 Pooled Retinal Vein Occlusion
- •6.2.7.2 Branch Retinal Vein Occlusion
- •6.2.7.3 Central and Hemicentral Retinal Vein Occlusion
- •6.2.8 Serum Folate
- •6.2.9 Serum B12
- •6.2.10 Smoking
- •6.2.11 Alcohol Consumption
- •6.2.14 No Underlying Vascular Risk Factor
- •6.3 Ocular Associations
- •6.3.1 Pooled Retinal Vein Occlusion
- •6.3.2 Branch Retinal Vein Occlusion
- •6.3.3 Central Retinal Vein Occlusion and Hemicentral Retinal Vein Occlusion
- •6.4 Practical Recommendations About the Systemic Workup of Patients with Retinal Vein Occlusion
- •History of the Standard Workup for Systemic Associations in Central Retinal Vein Occlusion
- •6.5 Retinal Vein Occlusion and Cardiovascular Disease Risk
- •6.6 Differences in Systemic Associations Between Ischemic and Nonischemic CRVOs
- •6.7 Summary of Key Points
- •References
- •7.1 Branch Retinal Vein Occlusion
- •7.1.1 Acute Phase
- •7.1.1.1 Symptoms
- •7.1.2 Clinical Signs
- •7.1.2.1 Visual Acuity
- •7.1.3 Chronic Phase
- •7.1.3.1 Clinical Signs
- •7.1.3.2 Visual Acuity
- •Why Does the Visual Outcome in Nonischemic, Macula-Involving Branch Retinal Vein Occlusions Usually Vary with the Size of the Involved Retina?
- •7.2 Central Retinal Vein Occlusion
- •7.2.1 Acute Phase
- •7.2.1.1 Symptoms
- •7.2.1.2 Clinical Signs
- •When Retinal Venous Congestion and Optic Disc Edema Are Not Central Retinal Vein Occlusion
- •What Is the Relationship of Central Retinal Artery Pressure and Cilioretinal Artery Pressure?
- •Retinal Whitening Does Not Equal Infarction
- •A Clinical Picture Predicted by a Hypothesis
- •7.2.1.3 Visual Acuity
- •7.2.2 Chronic Phase
- •Why Are Optic Disc Collaterals Associated with Worse Initial and Final Visual Acuity After CRVO?
- •7.2.2.1 Visual Acuity
- •7.3 Hemicentral Retinal Vein Occlusion
- •7.3.1 Clinical Signs
- •7.3.2 Visual Acuity
- •7.4 Summary of Key Points
- •References
- •Which Measure of Reproducibility Is Best?
- •8.1 Color Fundus Photography
- •8.2 Fluorescein Angiography
- •8.2.1 Branch Retinal Vein Occlusion
- •8.2.2 Central Retinal Vein Occlusion
- •8.3 Optical Coherence Tomography and the Retinal Thickness Analyzer
- •Methods of Analysis of OCT in RVO
- •8.4 Visual Field Testing
- •8.5 Electroretinography
- •Electroretinography Essentials for Retinal Vein Occlusions
- •8.5.1 Branch Retinal Vein Occlusion
- •8.5.2 Central Retinal Vein Occlusion
- •8.5.3 Hemicentral Retinal Vein Occlusion
- •8.6 Indocyanine Green Angiography
- •8.7 Color Doppler Ultrasonographic Imaging
- •8.8 Laser Doppler Flowmetry
- •8.9 Ophthalmodynamometry
- •8.10 Scanning Laser Doppler Flowmetry
- •8.11 Laser Interferometry to Measure Pulsatile Choroidal Blood Flow
- •8.12 Vitreous Fluorophotometry
- •8.13 Summary of Key Points
- •References
- •9.1 Terminology
- •9.2 Branch Retinal Vein Occlusion
- •9.3 Central Retinal Vein Occlusion
- •9.3.1 Clinical Characteristics
- •In the Face of Evidence that Fluorescein Angiography Is Poorly Predictive of Ischemia in Acute Central Retinal Vein Occlusion, Why Is It Widely Used?
- •9.3.2 Conversion from Nonischemic to Ischemic Central Retinal Vein Occlusion
- •9.3.3 Outcomes by Ischemic Status
- •9.4 Interaction of Ischemia with Effects of Treatments
- •9.4.1 Branch Retinal Vein Occlusion
- •9.4.2 Central Retinal Vein Occlusion
- •9.5 Summary of Key Points
- •References
- •10.1 Branch Retinal Vein Occlusion
- •10.2 Central Retinal Vein Occlusion
- •10.3 Hemicentral Retinal Vein Occlusion
- •10.4 Treatment of Posterior Segment Neovascularization in Retinal Vein Occlusion
- •10.5 Summary of Key Points
- •References
- •11.1 The Pathoanatomy and Pathophysiology of Iris and Angle Neovascularization
- •11.2 Clinical Picture of Anterior Segment Neovascularization
- •11.4 Anterior Segment Neovascularization in Branch Retinal Vein Occlusion
- •11.5 Anterior Segment Neovascularization in Central Retinal Vein Occlusion
- •The Problem of Undetected Anterior Segment Neovascularization After Central Retinal Vein Occlusion
- •Why Is Anterior Segment Neovascularization Less Common in Central Retinal Vein Occlusion Than in Central Retinal Artery Occlusion?
- •11.6 Anterior Segment Neovascularization in Hemicentral Retinal Vein Occlusion
- •11.7 Summary of Key Points
- •References
- •12.1 Branch Retinal Vein Occlusion with Macular Edema
- •12.2 Central Retinal Vein Occlusion with Macular Edema
- •12.3 Summary of Key Points
- •References
- •Visual Acuity Measurement in Treatment Studies
- •OCT Measurement of Macular Thickness in Treatment Studies
- •13.1 Medical Treatment of Retinal Vein Occlusion
- •13.1.1 Anticoagulation
- •13.1.2 Systemic Thrombolytic Therapy
- •13.1.3 Isovolumic Hemodilution
- •Recipe for Isovolumic Hemodilution
- •13.1.4 Plasmapheresis
- •13.2 Treatment of Previously Unsuspected Risk Factors for Retinal Vein Occlusion
- •13.3.1 Treatments for Macular Edema
- •Relative Corticosteroid Potencies
- •13.3.2 Treatments for Intraocular Neovascularization
- •13.4 Results of Clinical Studies of Treatments for Macular Edema Secondary to Retinal Vein Occlusions
- •13.4.1 Branch Retinal Vein Occlusion
- •13.4.1.1 Grid Laser
- •13.4.1.2 Subthreshold Grid Laser Treatment
- •13.4.1.3 Sector Panretinal Laser Photocoagulation
- •13.4.1.5 Posterior Subtenon’s Triamcinolone
- •13.4.1.6 Intravitreal Corticosteroids
- •13.4.1.7 Combination Treatments Involving Intravitreal Triamcinolone Injections
- •13.4.1.8 Arteriovenous Sheathotomy
- •13.4.1.9 Vitrectomy
- •13.4.1.10 Intravitreal Injection of Autologous Plasmin
- •13.4.2 Central Retinal Vein Occlusion
- •13.4.2.2 Combination Regimen: Bevacizumab, Panretinal Laser, and Grid Laser
- •13.4.2.3 Systemic Corticosteroids
- •13.4.2.4 Posterior Subtenon’s Triamcinolone Injection
- •13.4.2.5 Intravitreal Corticosteroids
- •13.4.2.6 Vitrectomy
- •13.5 Treatment of Intraocular Neovascularization
- •13.5.1 Sector Panretinal Laser Photocoagulation for Retinal and Disc Neovascularization After Branch Retinal Vein Occlusion
- •13.5.2 Vitrectomy for Intraocular Neovascularization with Vitreous Hemorrhage
- •13.5.3 Laser Panretinal Photocoagulation for Anterior Segment Neovascularization
- •13.6 Economic Considerations
- •13.7 Future Directions
- •13.8 Summary of Key Points
- •References
- •14.1 Pooled Retinal Vein Occlusions in the Young
- •14.2 Branch Retinal Vein Occlusion in Younger Patients
- •14.3 Central Retinal Vein Occlusion in Younger Patients
- •14.4 Workup in the Younger Patient with Retinal Vein Occlusion
- •14.5 Summary of Key Points
- •References
- •15.1 Failed and Unadopted Treatments for Branch Retinal Vein Occlusion
- •15.1.1 Sector Panretinal Laser Photocoagulation for Serous Retinal Detachment in Branch Retinal Vein Occlusion
- •15.1.2 Laser Chorioretinal Venous Anastomosis for Branch Retinal Vein Occlusion with Macular Edema
- •15.1.3 Intravenous Infusion of Tissue Plasminogen Activator
- •15.1.4 Intravitreal Injection of Tissue Plasminogen Activator
- •15.1.5 Macular Puncture for Branch Retinal Vein Occlusion with Macular Edema
- •15.2 Failed and Unadopted Treatments for Central Retinal Vein Occlusion
- •15.2.1 Grid Laser for Macular Edema in Central Retinal Vein Occlusion
- •15.2.2 Chorioretinal Venous Anastomosis for Nonischemic Central Retinal Vein Occlusion with Macular Edema
- •15.2.3 Radial Optic Neurotomy for Central Retinal Vein Occlusion
- •15.2.4 Retinal Endovascular Surgery with Intravenous Injection of Tissue Plasminogen Activator
- •15.2.5 Intravitreal Injection of Tissue Plasminogen Activator
- •15.2.6 Intravitreal Tissue Plasminogen Activator and Triamcinolone
- •15.2.7 Systemic Acetazolamide for Central Retinal Vein Occlusion with ME
- •15.2.8 Combined Central Retinal Vein Occlusion and Central Retinal Artery Occlusion
- •15.2.9 Optic Nerve Sheath Decompression
- •15.2.10 Section of the Posterior Scleral Ring
- •15.2.11 Infusion of High Molecular Weight Dextran
- •15.3 Failed and Unadopted Treatments for HCRVO
- •15.4 Summary of Key Points
- •References
- •16.1 Case 16.1: An Asymptomatic Central Retinal Vein Occlusion with Asymmetric Hemispheric Involvement
- •16.1.1 Discussion
- •16.2 Case 16.2: Chronic Macular Branch Vein Occlusion with Subtle Ophthalmoscopic Signs, More Obvious Fluorescein Angiographic Signs, and Macular Edema
- •16.2.1 Discussion
- •16.3 Case 16.3: Old Hemicentral Retinal Vein Occlusion with Late Vitreous Hemorrhage and Hyphema
- •16.3.1 Discussion
- •16.4 Case 16.4: Spontaneous Improvement of a Nonischemic Central Retinal Vein Occlusion
- •16.4.1 Discussion
- •16.5 Case 16.5: Conversion of a Nonischemic Hemicentral Retinal Vein Occlusion to an Ischemic One
- •16.5.1 Discussion
- •16.6 Case 16.6: Nonarteritic Ischemic Optic Neuropathy Following Branch Retinal Vein Occlusion
- •16.6.1 Discussion
- •16.7 Case 16.7: Differentiating Central Retinal Vein Occlusion from the Ischemic Ocular Syndrome
- •16.7.1 Discussion
- •16.8 Case 16.8: Late Development of Neovascularization Elsewhere After Ischemic Branch Retinal Vein Occlusion
- •16.8.1 Discussion
- •16.9 Case 16.9: Nonischemic Central Retinal Vein Occlusion with Secondary Branch Retinal Artery Occlusion
- •16.9.1 Discussion
- •16.10 Case 16.10: Nonischemic Central Retinal Vein Occlusion with Macular Edema or Asymmetric Diabetic Retinopathy with Diabetic Macular Edema?
- •16.10.1 Discussion
- •16.11 Summary of Key Points
- •References
- •Index
58 |
2 Pathophysiology of Retinal Vein Occlusions |
VEGF and ICAM-1 and vitreous levels of EPO and IL-6 have been found to correlate with degree of retinal nonperfusion and severity of macular edema.129,137,148,149,151,155 Vitreous levels of IL-8 and MCP-1 are correlated in BRVO.133 Vitreous levels of IL-6 have been found to correlate with the area of retinal nonperfusion.149 Preoperative levels of VEGF and IL-8 have been found to correlate with the magnitude of reduction in macular thickness after vitrectomy for BRVO with macular edema.146 VEGF levels are higher in eyes with BRVO that develop subretinal fluid than in eyes that develop cystoid macular edema without subretinal fluid.150 Vitreous levels of soluble ICAM-1 have been found to correlate with perifoveal capillary blood flow velocity in a study of patients with pooled RVO, mostly BRVO. Vitreous VEGF concentration was not correlated with perifoveal capillary blood flow velocity.143 The increased concentrations of the inflammatory mediators IL-6, IL-8, and MCP-1 suggest a common pathway involving inflammation in BRVO.136
Reports of vitreous PEDF levels have been inconsistent in BRVO: both elevated and decreased levels have been reported.122 PEDF levels have been reported to correlate negatively with vitreous VEGF levels and severity of macular edema in BRVO.122
The following molecules are not elevated in BRVO:
•(Growth factors) EGF, bFGF, G-CSF, and GM-CSF
•(Chemokines) eotaxin, MIP-1a, MIP-1b, RANTES
•(Cytokines) IL-1b, IL-2, IL-4, IL-10, IL-17, IFN-g, and TNF-a100
In BRVO, upregulation of VEGF continues for at least 2 years whether collateral vessels develop or not. The evidence for this is based on the need to block VEGF by monthly injections of ranibizumab.154
Nonhuman primate models in which intravitreal VEGF levels increase after branch venous occlusions do not show preretinal neovascularization, suggesting that cytokines other than VEGF are required for the clinical finding of posterior segment neovascularization in humans after BRVO.99
2.3.4.4 Molecular Signaling in CRVO
The situation regarding molecular signaling in CRVO resembles that in BRVO. Differences between the two conditions relate to the fact that fewer factors have been investigated in CRVO. In CRVO, elevated levels of these cytokines have been found: VEGF, soluble vascular endothelial growth factor receptor-2, IL-8, IL-6, erythropoietin, and MCP-1.130,137,155,156 Vitreous VEGF levels correlate with severity of macular edema and ischemia in CRVO.130,136,137,157 The vitreous levels of IL-6 and VEGF are elevated in CRVO compared to controls, but the serum levels are not, implying intraocular production of these factors.136 The vitreous levels of IL-6 are correlated with the severity of macular edema of CRVO.130 Elevated levels of IL-6, IL-8, and MCP-1 were highly correlated in one study, suggesting a common pathway involved in their common upregulation.136 These molecules are not elevated in CRVO:
•(Cytokines) IL-1b, IL-2, IL-4, IL-5, IL-10, IL-17, IFN-g, and TNF-a
•(Chemokines) eotaxin, MIP-1a, MIP-1b, and RANTES
•(Growth factors) EGF, bFGF, G-CSF, and GM-CSF136
In human CRVO, a correlation exists between aqueous VEGF concentration and the onset, persistence, and regression of neovascularization of the iris (NVI).114 In one study, the threshold for onset of NVI was 849 pg/ml similar to the dissociation constant for binding of VEGF to the VEGF1 receptor. The threshold for regression of NVI following PRP was lower, at 378 pg/ml, implying that the VEGF required to sustain established neovascularization is lower than that required to induce NVI.114
The blood–aqueous barrier (BAB) and the blood–retina barrier (BRB) are both disrupted by BRVO and CRVO. Using fluorophotometry, aqueous and posterior vitreous fluorescein concentrations were higher in eyes with BRVO and CRVO than in unaffected fellow eyes or of agematched control eyes.117 Moreover, the degree of barrier breakdown was greater in CRVO than BRVO and greater in ischemic CRVO than nonischemic CRVO.117 All of these relationships are what one would expect if VEGF is the mediator of the BAB and BRB breakdown.