What are the etiologies of arterial, venous, and capillary retinal vasculitides?

Etiologies of Retinal Vasculitides by Vascular Compartment

Arterial Retinal Vasculitis

Arterial retinal vasculitis is predominantly caused by giant cell arteritis (GCA), systemic lupus erythematosus, and necrotizing vasculitides, with GCA being the most critical to identify due to its risk of bilateral blindness. 1, 2

• Giant cell arteritis is the most common arteritic cause, affecting medium and large extracranial arteries including distal carotid branches, resulting in occlusive intimal hyperplasia that can lead to central retinal artery occlusion (CRAO) and arteritic anterior ischemic optic neuropathy 1
• Systemic lupus erythematosus is associated with arterial or mixed arteriovenous vasculitis, with patients having a 3.5-fold increased incidence of retinal vascular occlusions 1, 2
• Necrotizing vasculitides (including Wegener's granulomatosis) can cause arterial involvement, though less frequently observed than venous disease 2, 3
• Infectious etiologies including bacterial, viral, fungal, and parasitic infections tend to exhibit arterial sheathing or occlusion with associated ischemic areas 4
• Autoimmune disorders beyond those listed can rarely manifest as arterial vasculitis, particularly in the setting of combined arterial and venous occlusions 1

Venous Retinal Vasculitis (Retinal Phlebitis)

Venous vasculitis is most commonly associated with Behçet's disease, sarcoidosis, and multiple sclerosis, with Behçet's disease being the predominant systemic association. 2, 3

• Behçet's disease is the most frequently encountered systemic disease causing venous retinal vasculitis, predominantly involving retinal veins 2, 5
• Sarcoidosis commonly presents with venous involvement and may be associated with branch retinal vein occlusion 6, 2
• Multiple sclerosis is associated with predominantly venous vasculitis 2
• Retinal phlebitis may be associated with branch retinal vein occlusion (BRVO), though it is critical to distinguish true inflammatory phlebitis from thrombotic/embolic retinal vein occlusions, which are not primary vasculitides 1, 7
• Infectious causes can involve venous sheathing, particularly in bacterial, viral, fungal, or parasitic infections 4
• Idiopathic retinal vasculitis commonly presents with venous predominance when no systemic association is identified 5

Capillary Retinal Vasculitis

Capillary vasculitis is predominantly associated with noninfectious autoimmune conditions and represents a distinct pattern from the ischemic arterial or venous occlusive patterns seen in infectious vasculitis. 4

• Noninfectious retinal vasculitis is predominantly associated with capillary vasculitis, distinguishing it from infectious causes which tend to show arterial or venous sheathing/occlusion with ischemic areas 4
• Systemic inflammatory diseases including rheumatoid arthritis can manifest with capillary-level inflammation 3
• Autoimmune conditions with genetic susceptibility (HLA associations and cytokine polymorphisms) may induce capillary vasculitis through cross-reactivity with autoantigens following antecedent infection 5

Critical Clinical Distinction

A key diagnostic principle: infectious vasculitis typically exhibits ischemic areas with arterial or venous sheathing/occlusion, while noninfectious vasculitis predominantly shows capillary vasculitis without the same degree of vascular occlusion. 4 This distinction is essential for guiding appropriate antimicrobial versus immunosuppressive therapy and preventing irreversible vision loss from delayed treatment.