SARS-CoV-2 RNA found on ocular surfaces and in tears of patients with COVID-19

Investigators evaluated the rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in tears collected from a conjunctival swab of patients with COVID-19 in intensive care units in Italy, and the rate in healthy participants.

Study design

Investigators evaluated the rate of SARS-CoV-2 in tears collected from patients with COVID-19 by means of real-time reverse transcriptase–polymerase chain reaction (rRT-PCR) assay. They also assessed the association of virus presence with concomitant clinical conditions and local clinical conditions. The authors conducted a cross-sectional study between April 9 and May 5, 2020, in intensive care units in Lombardy, Italy. A total of 108 participants (mean age 58.7 years; 55 female) were tested for SARS-CoV-2 using rRT-PCR assay. A conjunctival swab was performed in 91 patients hospitalized for COVID-19, which was clinically diagnosed by rRT-PCR assay on nasopharyngeal swabs and by radiological imaging. Conjunctival swabs from 17 additional healthy volunteer participants with no symptoms of COVID-19 were examined to evaluate the availability and applicability of the conjunctival swab test.

Outcomes

SARS-CoV-2 was found on the ocular surface in 52 of 91 patients with COVID-19, with a wide variability in the mean viral load from each eye. Among a subset of 41 patients, concordance of 63.0% was found between positive conjunctival and nasopharyngeal swab test results when performed within 2 days of each other. In 17 of these patients, nasopharyngeal swab results were negative for SARS-CoV-2. In 10 of these 17 patients, conjunctival swab results were positive for the virus.

Limitations

The authors could not determine the infectivity of the viral material detected and thus the definitive clinical relevance. Other limitations include the cross-sectional design of the study, which lacks long-term prospective evaluation of the patients. The limited number of negative conjunctival swabs in the presence of a positive nasopharyngeal test in patients with COVID-19 may be due to difficulties in sampling patient's tears. Ongoing development of procedures and laboratory testing tools may improve the ability to investigate this use in the future.

Clinical significance

SARS-CoV-2 RNA was present on ocular surfaces in a large portion of the study cohort. Findings suggest that individuals with COVID-19 may test positive with a conjunctival swab and test negative with a nasopharyngeal swab. The slightly invasive conjunctival swab may be considered as a supplementary diagnostic test for COVID-19. These results also suggest that SARS-CoV-2 may diffuse from ocular surfaces to the body.