Abstract

Central retinal vein occlusion (CRVO) is a significant cause of vision loss worldwide, characterized by the blockage of the central retinal vein, leading to retinal ischemia, edema, and consequent visual impairment. The pathophysiology involves venous congestion and increased retinal capillary permeability, potentially resulting in permanent damage if not addressed promptly. Although CRVO is primarily associated with systemic conditions such as hypertension, diabetes mellitus, and hypercoagulability, recent observations have suggested an association with COVID-19 vaccination, particularly in individuals with underlying risk factors. Given the widespread administration of COVID-19 vaccines globally, understanding the potential ocular complications is crucial for informed risk- benefit analysis and patient management. The emergence of rare reports describing retinal vascular events following COVID-19 vaccination has raised questions about the vaccine's role in triggering or exacerbating conditions like CRVO. These cases often involve various COVID-19 vaccines, including vector-based and mRNA vaccines, and are typically reported within days to weeks post- vaccination. The potential mechanisms linking COVID-19 vaccines to CRVO include immune-mediated responses, vaccine-induced thrombotic thrombocytopenia (VITT), and molecular mimicry, which could theoretically precipitate retinal vascular events. For instance, VITT is characterized by thrombosis in unusual sites and has been predominantly associated with adenoviral vector vaccines such as AstraZeneca's ChAdOx1 nCoV-19 and Johnson & Johnson’s Ad26.COV2.S, which could increase the risk of vascular occlusions, including in the retina (Greinacher et al., 2021; Schultz et al., 2021). Understanding factors contributing to CRVO post-COVID-19 vaccination requires examining potential precipitating conditions, including pre-existing comorbidities (e.g., cardiovascular diseases), the type of vaccine administered, and individual immune responses. The temporal relationship between vaccination and CRVO onset remains a critical area of investigation, necessitating more robust epidemiological studies and case- control analyses to establish causality (Simpson et al., 2022). This review aims to elucidate the factors potentially contributing to blindness secondary to CRVO in the context of COVID-19 vaccination, emphasizing the need for vigilance in identifying early symptoms and providing timely interventions.