To investigate the presence of SARS-CoV-2 RNA (Severe Acute Respiratory Syndrome corona virus 2 Ribo nucleic acid) in tears of moderate to severe COVID-19 patients.
Cross sectional study SUBJECTS: Laboratory proven moderate to severe COVID-19 patients METHODS: Tears were collected within 48 hours of laboratory confirmation using three methods (group 1) conjunctival swab + Schirmer's strips, (group 2) conjunctival swab, (group 3) Schirmer's strips. Samples from both the eyes of each patient were transported in a single viral transport media (VTM) for real time-reverse transcriptase- polymerase chain reaction (real-time RT-PCR). Detailed demographic profile, systemic symptoms, co morbidity and ocular manifestations were noted.
MAIN OUTCOME MEASURE
Viral load of a sample was determined using cyclic threshold (Ct) value of E gene. A specimen was positive if the amplification curve for the E gene crossed the threshold line within 35 cycles and positive on RNA-dependent RNA polymerase (RdRp) or Open reading frame 1b (ORF 1b) gene assay.
Of the 78 cases enrolled in the study, samples of 3 patients were found inadequate for analysis. Thirty-six (48%) were moderate while 39 (52%) were severe COVID-19 cases with no ocular involvement in any patient. In the 75 patients, RT-PCR of tears was positive in 18 patients (24%) and 29 out of 225 (12.9%) samples were positive. Positivity in group 1, 2 and 3 being 11 (14.7%), 11 (14.7%) and 7 (9.3%) respectively (p=0.3105). Mean Ct values in group 1, 2 and 3 were 28.36±6.15, 29.00±5.58 and 27.86±6.46 (p=0.92) respectively. Five patients had positive RT PCR by all 3 methods (mean Ct values 25.24±6.33) and 12 patients were positive by either of the 3 methods (mean Ct value being 32.16±1.94), the difference in Ct values being statistically significant (p=0.029). The median value of symptomatology in patients with positive RT-PCR in tears was 5 days (4-9 days).
SARS-CoV-2-RNA was detected in tears of 24% of laboratory proven moderate to severe COVID 19 patients. Conjunctival swab remains the gold standard of tear collection for RT-PCR assay. There is significantly higher possibility of viral transmission through tears in moderate to severe COVID-19 patients.