SARS-COV-2 viral load in tears of patients with COVID-19 in the early symptomatic stages: comparison of two different tear sampling methods

PURPOSE: To evaluate the presence of SARS-CoV-2 virus in tears of patients with COVID-19 in the early symptomatic stages and to compare two different sampling methods. MATERIALS AND METHOD: In this cross-sectional study, tears sampling was performed in COVID-19 patients admitted within the first 7 days of symptom onset. The samples were collected with both conjunctival swabs and Schirmer strips. Each specimen was analyzed via RT-PCR. The viral load was evaluated in terms of the cycle threshold value. Ocular and systemic symptoms and comorbidities of the patients were also recorded. RESULTS: Forty patients were included. The average time from the initiation of symptoms was 3.15 days. Unilateral conjunctivitis has been observed in 5% of patients and foreign body sensation in 7.5% of patients. No viral RNA was detected in the tear samples of the patients with ocular findings. The positivity rate for SARS-CoV-2 in tears was 2.5% (n = 1). None of the samples collected by Schirmer test strips yielded positive polymerase chain reaction result for SARS-COV-2. The Ct value of the positive conjunctival swab was 36.03 and the nasopharyngeal Ct value of the same patient was 25.68. CONCLUSION: The SARS-CoV-2 viral shedding rate has been determined as 2.5% in the tears of early symptomatic stage COVID-19 patients. The viral load of the tears was lower than the naso-oropharynx. The conjunctival swab method is recommended in tear collection to evaluate the presence of SARS-CoV-2 by RT-PCR analysis in low viral load tears.