COVID-19 not present in patients' tears in Singapore suggesting ocular transmission is low

Roibeard O’hEineachain

Published: Monday, March 30, 2020

A new study involving 17 COVID-19 patients failed to detect the presence of the virus in a study conducted Singapore, suggesting a low risk of ocular transmission of the virus https://www.aaojournal.org/article/S0161-6420(20)30311-0/fulltext The patients in the study had positive for COVID-19 by reverse transcriptase polymerase chain reaction (RT-PCR) of nasopharyngeal samples in a clinical diagnostic laboratory. A total of 64 samples of tears were sampled by a senior consultant ophthalmologist using Schirmer’s test strips at varying timepoints between day 3 and 20 after the initial development of symptoms. Over the study period, with 12, 28 and 24 samples taken from the first, second and third week of initial symptoms respectively. The investigators found that virus could not be detected in the by RT-PCR or viral. The authors noted that further studies are needed, including research on the association between serum viral load and viral shedding in tears. Some basic c science research is also need to establish whether angiotensin-converting enzyme 2 (ACE2) is present in corneal and conjunctival cells. The COVID-19 virus has been shown to infect cells via ACE2 receptors, they wrote.