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To the Editor We read with interest the article of Wu et al1 on the characteristics of ocular findings in patients with novel coronavirus disease (COVID-19). Wu et al1 reported that ocular manifestations consistent with conjunctivitis were found in 12 of 38 patients (31.6%) with COVID-19 and concluded that ocular abnormalities frequently occurred in patients with more severe COVID-19 and acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could be transmitted via the eyes. However, we consider that the conjunctivitis Wu et al1 described in their article may not be caused by SARS-CoV-2 infection, ophthalmic involvement may not be associated with the severity of COVID-19, and the eye is not likely to play as a transmission route of SARS-CoV-2 infection, based on previous investigations and the findings of Wu et al.1
As we know, viral conjunctivitis is typically characterized by diffuse conjunctival congestion and watery secretion, followed by mucinous or mucopurulent discharge.2 Conjunctival congestion accompanied by COVID-19 may be associated with SARS-CoV-2 infection or nonpathogenic causes, such as dry eye and chronic noninfective conjunctivitis, because of long-term short-distance reading or entertainment, which is quite common during quarantine.3 In fact, conjunctival congestion and increased secretion only existed in 2 of the 12 patients with conjunctivitis reported by Wu et al.1 Moreover, Wu et al1 did not describe whether the patients recruited in their study had a medical history of ophthalmic diseases and how long the patients spent on short-distance reading or entertainment. Hence, their conclusion that the ophthalmic involvement is associated with the severity of COVID-19 may not be appropriate.
Although conjunctiva is directly exposed to infectious droplets and fomites contaminating the ocular surface via splashing or hand-to-eye touching, viral conjunctivitis rarely occurs in patients with COVID-19.2-4 Viral conjunctivitis has been reported in 5 cases and SARS-CoV-2 RNA detected in 5 patients with COVID-19.2 These reports, however, do not determine the prevalence among individuals with COVID-19. The rarity of viral conjunctivitis in patients with COVID-19 may be interpreted by the less abundant expression of angiotensin-converting enzyme 2, the entry receptor of SARS-CoV-2, on conjunctival epithelial cells and poor binding capability of angiotensin-converting enzyme 2 protein on conjunctival epithelial cells to SARS-CoV-2 spike protein, as well as the protective effect of the antimicrobial agents in tears (eg, lactoferrin and secretory IgA) and tear rinsing, which continuously eliminate the viruses on ocular surface into nasal cavity through nasolacrimal duct.2 Hence, the conjunctiva is likely not a preferred portal of entry for SARS-CoV-2 to cause respiratory tract infection; SARS-CoV-2 exposed to the ocular surface may be continuously transported to nasal and nasopharyngeal mucosa by constant tear rinsing through the nasolacrimal duct and then cause COVID-19.2,4,5
Corresponding Author: Chuan-bin Sun, MD, PhD, Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Jiefang Rd 88, Hangzhou 310009, Zhejiang Province, China (firstname.lastname@example.org).
Published Online: December 23, 2020. doi:10.1001/jamaophthalmol.2020.5813
Conflict of Interest Disclosures: None reported.
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Liu Z, Xiao Q, Sun C. Conjunctival Findings in Patients With Coronavirus Disease 2019. JAMA Ophthalmol. 2021;139(2):253–254. doi:10.1001/jamaophthalmol.2020.5813