Risk of New Retinal Vascular Occlusion After Messenger RNA COVID-19 Vaccination Within Aggregated Electronic Health Record Data

Abstract

To the Editor We have several comments regarding the article by Dorney et al. 1 First, the study investigated the potential link between messenger RNA (mRNA) COVID-19 vaccination and the risk of retinal vein occlusion (RVO) through a retrospective cohort design involving 4 cohort groups.Of note, group 3 and group 4 were queried for influenza vaccine and the tetanus, diphtheria, and pertussis vaccine between 2018 to 2019, while group 1 and group 2 were queried for COVID-19 vaccination between 2020 and 2022. These different times could represent a confounding factor that might be addressed if the authors 1 could confirm their findings with alternative designs, such as a self-controlled case series or an analysis of time-varying covariates using a Cox model to try to minimize time bias. 2,3 Also, several studies have reported RVO after the second dose or booster of the mRNA COVID-19 vaccination, 4,5 while other reports of vaccine-related occlusion of the central retinal artery/vein have presented no difference between the first and second dose of the COVID-19 vaccination. 2,3 Dorney et al 1 reported a higher risk of RVO after the first dose of the mRNA COVID-19 vaccination compared with the second dose. This potential inconsistency with previous studies can weaken confidence in their conclusions.In addition, the authors 1 have presumed a hyperviscous state related to RVO after the first dose of a COVID-19 vaccination. However, other studies have not shown hypercoagulable status after receiving mRNA COVID-19 vaccination. Hence, it might be better to match and adjust coagulation parameters at baseline.Lastly, the study does not appear to have distinguished between symptomatic and asymptomatic SARS-CoV-2 infections, which again could contribute to confounding factors. Perhaps individuals with a positive history of a polymerase chain reaction test positive for SARS-CoV-2 based on ICD-10 International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes should be excluded. The authors 1 are to be congratulated for their investigations and perhaps clarifying these weaknesses could improve the study and strengthen the conclusion.