Classifications of Retinal Vasculitis
Retinal vasculitis is primarily classified based on the type and size of retinal vessels involved (arteries, veins, or capillaries), the anatomic location of inflammation, and whether the disease is occlusive or non-occlusive. 1, 2
Primary Classification Framework
By Vessel Type Involved
- Arterial vasculitis: Inflammation predominantly affecting retinal arteries and arterioles 1, 2
- Venous vasculitis (retinal phlebitis): Inflammation primarily involving retinal veins, which may be associated with branch retinal vein occlusion 3, 1
- Capillary vasculitis: Inflammation of the retinal capillary network 1, 4
- Mixed vasculitis: Combined involvement of multiple vessel types 2, 5
By Vascular Occlusion Status
- Occlusive retinal vasculitis: Characterized by vascular occlusion, retinal ischemia, ischemic areas, arterial or venous sheathing or occlusion, and potential neovascularization 1, 4
- Non-occlusive retinal vasculitis: Inflammation without significant vascular occlusion, predominantly associated with capillary vasculitis 1, 4
By Anatomic Location
- Peripheral retinal vasculitis: Inflammation affecting the peripheral retinal vessels 2
- Posterior pole vasculitis: Inflammation involving vessels near the macula and optic disc 2
- Diffuse retinal vasculitis: Widespread involvement across multiple retinal zones 2
Secondary Classification by Etiology
Infectious Retinal Vasculitis
- Bacterial causes: Including tuberculosis, syphilis, and other bacterial infections 4, 6
- Viral causes: Such as herpes viruses, cytomegalovirus, and others 4, 6
- Fungal causes: Various fungal pathogens 4, 6
- Parasitic causes: Parasitic infections affecting the retina 4, 6
Key distinguishing feature: Infectious vasculitis tends to exhibit ischemic areas, arterial or venous sheathing or occlusion, and is usually associated with retinal or choroidal involvement. 4
Non-infectious Retinal Vasculitis
- Associated with systemic vasculitic diseases: Including Behçet's disease (predominantly venous involvement), sarcoidosis (predominantly venous), systemic lupus erythematosus (arterial or mixed), and necrotizing vasculitis 1, 5
- Associated with systemic autoimmune diseases: Such as multiple sclerosis (predominantly venous involvement) 5
- Isolated ocular retinal vasculitis: Retinal vasculitis without identifiable systemic disease association 1, 6, 2
Pathophysiologic mechanism: Non-infectious retinal vasculitis is caused by type-III hypersensitivity reactions, increased expression of intracellular adhesion molecules, and genetic susceptibility. 1
Clinical Pitfalls and Diagnostic Considerations
- Geographic variation matters: The prevalence and spectrum of etiologies show geographical variations, which should inform your differential diagnosis based on patient origin and travel history 4
- Distinguish infectious from non-infectious early: Infectious vasculitis typically presents with retinal or choroidal involvement and ischemic features, while non-infectious disease is predominantly associated with capillary vasculitis 4
- Venous involvement patterns: Behçet's disease, sarcoidosis, and multiple sclerosis predominantly cause venous vasculitis, whereas systemic lupus erythematosus and necrotizing vasculitis more commonly cause arterial or mixed patterns 5
- Occlusive disease complications: Occlusive retinal vasculitis carries higher risk for vitreous hemorrhage, neovascular glaucoma, and tractional retinal detachment, requiring more aggressive monitoring and treatment 1