Retinal vascular occlusion (RVO) is the second most prevalent cause of visual loss related to retinal vascular diseases, after diabetic retinopathy. Risk factors for retinal vascular occlusion include diabetes, hypertension, obesity, coronary artery disease, and stroke. Retinal artery occlusion is caused by vasospasm, vasculitis, reduced arterial perfusion, and thromboembolism of retinal arteries. In this retrospective cohort study, Taiwanese researchers investigated the risk of RVO after the messenger RNA (mRNA) COVID-19 vaccination.
In both vaccines (mRNA-1273 and BNT162b2), the mRNA sequence determines the structure and assembly of the immunogen, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) glycoprotein. The authors suggested that molecular mimicry of the S protein, which shares sequence homology with human proteins, may play a central role in RVO.
Notably, a recent animal study that investigated the possible ocular transmission and tropism of SARS-CoV-2 and its interaction with cells lining the blood-retinal barrier has shown that the prolonged presence of SARS-CoV-2 S protein (thirty days after the intravitreal injection in C57BL/6J mice) resulted in microaneurysms, retinal atrophy, and RVO. According to the authors, these findings of retinal vascular changes and long-term pathologies seen after prolonged presence of the S antigen may be related to symptoms registered in individuals with post-COVID syndrome. https://discovermednews.com/retinal-inflammation-after-intranasal-infection-with-sars-cov-2/
About the study
In this retrospective large-scale cohort study, the authors used data from the global TriNetX network to investigate the association between RVO and vaccination against COVID-19. Participants were divided into two cohorts: vaccinated and unvaccinated. In both cohorts, the exclusion criteria were: diagnosis of RVO six months before the index date and the use of antiplatelet drugs, anticoagulants, or contraceptives four weeks before the index date. To ensure the reliability of the results, the research team appropriately matched the baseline characteristics of both cohorts before analysis.
Results
The study included 6,755,737 individuals. They were divided into two cohorts, 883,177 vaccinated and 5,871,737 unvaccinated. The results showed that the overall risk of all forms of RVO was 2.19 times higher in the vaccinated cohort than in the unvaccinated cohort within the two years after the vaccination.
The cumulative incidence of RVO was significantly higher in the vaccinated cohort than in the unvaccinated cohort at twelve weeks and two years after the vaccination. Cox multivariate analysis showed that the risk of RVO increased significantly in the first two weeks after vaccination and persisted for twelve weeks.
Conclusion
According to the authors, it is difficult to establish a definitive association between RVO and vaccination because of limited evidence and the low frequency of this disease. This study underscores the need for further research. In addition, ophthalmologists should consider retinal vascular occlusion in vulnerable patients after COVID-19 vaccinations.
This article was published in the npj Vaccines.
Journal Reference
Li, JX, et al. Risk assessment of retinal vascular occlusion after COVID-19 vaccination. npj Vaccines 8, 64 (2023). https://doi.org/10.1038/s41541-023-00661-7
