Retinal Manifestations of Covid 19
The coronavirus disease 2019 (COVID-19) pandemic is an ongoing global health crisis that is caused by the acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of March 12, 2022, there have been over 450 million confirmed cases of COVID-19 and over 6 million deaths around the world. Although most research and therapeutic efforts are directed toward the respiratory complications of the disease, COVID-19 can also lead to significant ophthalmic manifestations. The most commonly reported of these is conjunctivitis, which in some patients may be the only manifestation of SARS-CoV-2 infection. While eyelid, ocular surface, and anterior segment manifestations of COVID-19 are well documented, posterior segment involvement is less common and has mainly been described in the form of case reports. In this article, we will provide an overview of the most commonly reported retinal manifestations of COVID-19.
Retinal Manifestations of COVID-19
The most common retinal manifestations of COVID-19 are microvascular changes like cotton wool spots and retinal microhemorrhages. Many of these patients had preserved visual acuity and pupillary reflexes, but there have also been instances where patients developed visual field defects. The SARS-CoV-2 infection has also been associated with new-onset paracentral acute middle maculopathy (PAMM) and acute macular neuroretinopathy (AMN), although a true relationship between these conditions and COVID-19 has yet to be established. Increased tortuosity of retinal vessels is another finding that has been documented in patients with COVID-19. However, many of these retinal findings can also be seen in septic patients and patients with conditions like diabetic retinopathy, making it difficult to establish a true causal relationship between SARS-CoV-2 infection and microvascular retinal changes.
Retinal Vein Occlusion
Central retinal vein occlusion (CRVO) has been identified as an important complication of COVID-19, as early detection and treatment are necessary for improved prognosis. SARS-CoV-2 infection is known to cause endothelial disruption, complement activation, and inflammation, leading to a hypercoagulable state that increases the risk of thrombus formation. Decreased vision and blurred vision are the most common presenting symptoms of CRVO and can start anytime from 5 days to 6 weeks after the initial onset of fever. Although CRVO is classically associated with risk factors like age, hypertension, glaucoma, and diabetes, COVID-19 has been shown to have a causal relationship with CRVO irrespective of patient age or comorbidities. Because timely diagnosis and management are crucial for vision preservation, clinicians should be vigilant about monitoring for signs of CRVO in patients with a history of COVID-19.
Retinal Artery Occlusion
Central retinal artery occlusion (CRAO) is a medical emergency that can lead to complete vision loss if not treated promptly and has also been documented in the context of SARS-CoV-2 infection. In case reports, patients developed sudden, unilateral, and painless vision loss two to six weeks after the initial onset of COVID-19 symptoms and were found to have mild-to-significant retinal whitening on fundus exam. However, it is important to note that most of these patients had additional underlying conditions like hypertension, obesity, and coronary artery disease, which may have placed them at a higher risk of developing CRAO. Regardless, because rapid identification and treatment are necessary to restore visual acuity, clinicians should consider CRAO in patients with a history of COVID-19 who present with sudden and painless vision loss.
Acute Macular neuroretinopathy
While there are many case reports documenting retinal changes in the setting of COVID-19, the presence of additional comorbidities and their effects on the retina cannot be excluded. Despite this, clinicians should still be aware of and assess for the retinal manifestations of SARS-CoV-2 infection to prevent any vision-threatening complications. Future studies to investigate whether these documented retinal changes are truly attributable to COVID-19 or are incidental findings in the setting of clinical intercurrences are warranted.
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