SARS-CoV-2 populates ocular surfaces in COVID-19 patients in Northern Italy

The results of a new study¹ suggest that SARS-CoV-2 may diffuse from the ocular surfaces to the patient’s body, and use of a conjunctival swab may be another method of diagnosing the virus, according to Claudio Azzolini, MD, from the Unit of Ophthalmology, Azienda Socio-Sanitaria Territoriale (ASST) dei Sette Laghi, Department of Medicine and Surgery, University of Insubria, Varese, Italy,

Azzolini and colleagues investigated the rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detected in the tears of patients with COVID-19 based on the hypothesis that bodily fluids may serve as the conduits of viral spread, although thus far “insufficient information is available on the presence of the virus in human tears,” they pointed out.

The investigators used real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) to detect the virus in the tear samples from 91 patients in 2 intensive care units in northern Italy, between April 9 and May 5, 2020.

COVID-19 had been clinically diagnosed using rRT-PCR performed on nasopharyngeal swabs and by radiology studies of these patients.

Seventeen healthy volunteers who provided conjunctival swabs served as controls. The mean age of the 108 study participants was 58.7 years (55 women).

“SARS-CoV-2 was found on the ocular surface in 52 of 91 patients with COVID-19 (57.1%; 95% CI, 46.3%-67.5%), with a wide variability in the mean viral load from both eyes,” the investigators said.

They also evaluated a subset of 41 patients who had nasopharyngeal and conjunctival swabs performed on the same day or within 2 days and reported a “concordance of 63.0% (95% CI, 41.0%-81.0%) was found between positive conjunctival and nasopharyngeal swab test results when performed within 2 days of each other.”

Seven of 17 patients (41.2%; 95% CI, 18.0%-67.0%) in the subset had negative conjunctival and nasopharyngeal swabs, and the other 10 of these patients had negative nasopharyngeal swabs but positive conjunctival swabs.

This study showed that SARS-CoV-2 RNA was on the ocular surface in more than half of the patients in the COVID-19 cohort. 

“Because patients may have positive test results with a conjunctival swab and negative results with a nasopharyngeal swab, use of the slightly invasive conjunctival swab may be considered as a supplementary diagnostic test,” the investigators advised.

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Reference
1. Azzolini C, Donati S, Premi E, et al. SARS-CoV-2 on ocular surfaces in a cohort of patients with COVID-19 from the Lombardy Region, Italy. JAMA Ophthalmol. Published online March 4, 2021. doi:10.1001/jamaophthalmol.2020.5464