COVID-19 and ocular complications: A review of ocular manifestations, diagnostic tools, and prevention strategies

BACKGROUND: The novel severe acute respiratory syndrome coronavins 2 (SARS-CoV-2) led to the severe Corona Virus Disease 2019 (COVID-19) outbreak that started in December 2019 in China and caused enormous health and economic problems worldwide. Over time, SARS-CoV-2 has demonstrated the capacity for mutation. As the most prevalent new coronavirus variety worldwide, the Omicron variant has supplanted the Delta variant. The COVID-19 primarily damages the immune system and the lungs, but it can also harm other organs secondarily, depending on the patients' co-existing conditions. MAIN TEXT: COVID-19 is associated with ophthalmic manifestations such as conjunctival congestion, tear overflow, and conjunctival edema, with the majority of eye complications occurring in patients with severe infection. The virus may make a patient more susceptible to thrombotic conditions that affect venous and arterial circulation. Meanwhile, it can lead to efferent complications and mucormycosis which is more common in patients with diabetes or who have critical or severe SARS-CoV-2 infection. Significantly, there are a number of ocular side effects following the COVID-19 vaccination, such as herpetic keratitis and facial nerve palsy, which have been reported. These side effects may be caused by the vaccinations' propensity to trigger autoimmune symptoms or thromboembolic events. At present, large-scale nucleic acid testing mainly relies on nasopharyngeal swabs and throat swabs. Tear samples and conjunctival swabs may be helpful samples for the diagnosis of ocular SARS-CoV-2 infection. The eye could be a new route of infection, and finding ways such as effective environmental disinfection, scientific administrative control management, qualified personal protection and other measures to protect the eyes could further reduce the risk of infection. CONCLUSIONS: This review aims to sum up the ocular complications of COVID-19, the possible pathogenesis, and preventive strategies to protect ophthalmology practitioners and patients by reviewing the currently available literature on the topic.