|LETTER TO EDITOR
|Year : 2022 | Volume
| Issue : 3 | Page : 135-136
Retinal artery occlusion and COVID-19
Sunny Chi Lik Au
Department of Ophthalmology, Tung Wah Eastern Hospital, Hong Kong, China
|Date of Submission||06-Mar-2021|
|Date of Decision||29-Apr-2022|
|Date of Acceptance||03-May-2022|
|Date of Web Publication||1-Dec-2022|
Sunny Chi Lik Au
Department of Ophthalmology, Tung Wah Eastern Hospital, 9/F, MO Office, Lo Ka Chow Memorial Ophthalmic Centre, 19 Eastern Hospital Road, Causeway Bay, HKSAR, Hong Kong
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Lik Au SC. Retinal artery occlusion and COVID-19. J Clin Ophthalmol Res 2022;10:135-6
COVID-19 has been associated with thromboembolic disease due to its effect of endothelial dysfunction, platelet activation, and excessive inflammation from the “cytokine storm.” More case reports are now published to describe the blinding ocular arterial occlusion diseases (both the more proximal ophthalmic artery and the distal retinal artery) among COVID-19 patients as a result of hypercoagulable state.,, Besides, retinal vascular damage could be demonstrated by the altered ocular expression of the angiotensin-converting enzyme 2 (ACE2), particularly concentrated over the pigmented epithelial cells and photoreceptors. ACE2 plays an essential role in vascular protection, and in contrast, COVID-19 patients show a depletion of ACE2 function, both as a result of direct binding of ACE2 with SARS-CoV-2 and indirectly via ACE2 shedding and proteolytic processing.
Researchers are hypothesizing that the prothrombotic vascular endothelial microenvironment induced by SARS-CoV-2 virus could be the precipitating factor causing the development of retinal artery occlusion, similar to observation over other organs such as the renal microvasculature. This microvascular environment change was best demonstrated with the advancing optical coherence tomography angiography technology, where vascular density could be precisely measured. Despite an evolving association, there are still unanswered questions regarding the genuine retinal pathophysiology, especially patients in these case reports all process multiple metabolic and lifestyle risk factors. It is impossible to certain the association between retinal vessel occlusion and COVID-19, particularly with the lack of autopsy evidence when full effects of COVID-19 inflammatory and pro-coagulant state over the retinal vascular system are currently unknown. Under the COVID-19 pandemic, routine ophthalmic monitoring has been suspended in most places; underreporting definitely exists.
Both mild and severe COVID-19 patients are at higher risk of ocular microvascular complications. Patients with a severe illness such as COVID-19 may not be aware on their ocular symptoms. Physicians handling COVID-19 should also consider ocular symptoms and signs of possible ocular thromboembolic complication like painless acute visual loss. Trivial symptoms including painless acute vision loss, new onset scotomas, decreased vision and blurry vision. Ophthalmologists should stay alert and keep the suspicion on retinal vascular occlusions in patients with a history of COVID-19 infection, particularly those acute visual loss cases, as immediate interventions could prevent irreversible blindness.
During the pandemic, COVID-19 screening test is encouraged in patients diagnosed of retinal vascular occlusions, as SARS-CoV-2 carriers can be asymptomatic initially running the risk of SARS-CoV-2 transmission over the ophthalmology clinics. The increasing number of reported cases also highlighted the need to strictly follow the infection control protocols, particularly the personal protection equipment wear, when assessing patients with symptoms of blurry vision or signs of vessel occlusions. With the prevalence of SARS-CoV-2 infection, these patients could have an underlying undiagnosed active COVID-19.
In conclusion, the alteration of ocular microvasculature in COVID-19 patients may develop a new whole spectrum of posterior segment diseases as the retinal circulation is an end arterial system. The potentially vision-threatening nature of retinal vascular disease is of paramount clinical significance.
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Conflicts of interest
There are no conflicts of interest.
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