Systemic Risk Factors in Branch Retinal Vein Occlusion: a Comprehensive Review

Retinal vein occlusion (RVO) is a major cause of vision impairment globally. Obstruction in the retinal venous system is often due to thrombus formation at arteriovenous crossing points, leading to symptoms localized to the affected retinal area. Systemic conditions like hypertension, diabetes mellitus, dyslipidemia and heart disease are recognized risk factors for RVO, influencing the components of Virchow's triad.

This work aims to provide an updated overview of systemic risk factors associated with branch retinal vein occlusion (BRVO) development and to explore management options for the prevention or modification of associated risks.

Review of the literature concerning the pathogenesis and risk factors of BRVO, including diabetes mellitus, hyperlipidemia, hematologic conditions, hormonal factors, thyroid disease, and the impact of COVID-19 and related vaccines on BRVO incidence.

Diabetes mellitus contributes to BRVO through mechanisms like endothelial dysfunction and thrombogenesis. Hyperlipidemia - through lipid-mediated vascular changes - and hematologic conditions - by predisposing to hypercoagulability - significantly increase BRVO risk. Hormonal imbalances and thyroid diseases also influence BRVO development through their effects on vascular and hemostatic systems. Furthermore, COVID-19 has been identified as a potential risk factor for BRVO, possibly due to its pro- thrombotic effects.

Branch retinal vein occlusion represents a complex interplay of systemic and local vascular factors, necessitating comprehensive management strategies. Early detection and modification of risk factors is crucial for preventing vision impairment associated with BRVO. The ongoing pandemic and its systemic implications underscore the importance of continued review into the multifactorial etiology of BRVO and optimization of management strategies to improve patient outcomes.