Pradeep K Panigrahi1. 1. Department of Ophthalmology, Institute of Medical Sciences and SUM Hospital, Siksha O Anusandhan (Deemed to be) University, Bhubaneswar, Odisha, India.
Dear Editor,With great interest, I went through the article titled “Central retinal vein occlusion after mRNA SARS-CoV-2 vaccination” by Endo et al.[1] The authors have reported an interesting case of central retinal vein occlusion (CRVO) following vaccination for COVID-19. I have a few observations. During the initial presentation, all retinal veins in the left eye were dilated and tortuous with only a few retinal hemorrhages noted. Retinal hemorrhages were not present in all four quadrants to start with. I think it was a case of impending CRVO to begin with at the time of initial presentation. With time, as the blockade became more complete, retinal hemorrhages started appearing in all quadrants and the case progressed to full-blown CRVO. The authors have mentioned that there was a drop in vision to 20/30 eleven days after presentation. It will be interesting to know the cause of decreased vision at this time. Macular edema might be the most possible cause followed by macular ischemia. An optical coherence tomography scan of the left eye could have ruled out macular edema.The authors initially treated the case with intravitreal dexamethasone. However, there were no signs of intraocular inflammation. There was no vitreous inflammation and no evidence of retinal vasculitis. It will be interesting to know what prompted the authors to use intravitreal steroids at this stage. Following a drop in vision, the authors used a higher dose of intravitreal bevacizumab (2.5 mg/0.1 ml). We routinely use a dose of 1.25 mg/0.05 ml of bevacizumab to treat various retinal disorders. It will be enlightening to know the logic behind using a higher dose of bevacizumab in this case.There are reports of CRVO developing following intense physical exercise and dehydration in the literature.[23] The pathogenesis is severe dehydration leads to a rise in hematocrit, which then induces a hyperviscosity state in the blood circulation. This can predispose to thrombus formation within the retinal circulation, leading to a possible venous occlusion. It will be good to know if the patient had any history of dehydration prior to ocular symptoms. The authors have correctly mentioned that it is difficult to pinpoint the exact cause of CRVO in this case. The possible association with the COVID-19 vaccine in this case might be more coincidental rather than causal.