Título

SARS-COV-2 AND THE OCULAR SURFACE: TEST ACCURACY AND VIRAL LOAD

Objetivo

To evaluate the presence of SARS-CoV-2 RNA in the ocular surface and determine accuracy of different approaches of molecular testing based on nasopharynx positivity status for COVID-19.

Método

• Setting: institutional ; Design: Cross-sectional study • Participants: 152 individuals with suspected COVID-19 who underwent simultaneously nasopharynx and two different tear film collection techniques for real- time reverse transcription-quantitative polymerase chain reaction (RT-qPCR). • Observation procedures: Tear was collected randomized: one eye with Schirmer test and the contralateral eye with conjunctival swab/cytology. All individuals underwent slit lamp biomicroscopy and ocular clinical features were analyzed.

Resultado

86 (56.6%) patients had COVID-19 confirmed by nasopharynx PCR. Schirmer test was positive in 16.3% (14/86) and conjunctival swab/cytology in 17.4% (15/86). There were no positive ocular tests among those with negative nasopharynx PCR test. Overall agreement of ocular tests was 92.7%, and in combination, sensitivity would increase to 23.2%. Mean cycle threshold (Ct) values in nasopharynx, Schirmer, and conjunctival swab/cytology tests were 18.2 ± 5.3, 35.6 ± 1.4 and 36.4 ± 3.9, respectively. Ct values were statistically different between Schirmer (p = 0.001) and conjunctival swab/cytology (p < 0.001) tests compared to the nasopharynx test.

Conclusão

Schirmer (16.3%) and conjunctival swab (17.4%) tests were similarly capable of detecting SARS-CoV-2 RNA in the ocular surface by RT-PCR and demonstrated indistinct sensitivity and specificity. Simultaneous specimen sampling from nasopharynx and ocular tests demonstrated significantly lower viral load in both ocular surface approaches compared to the nasopharynx test. Ocular manifestations detected by slit lamp biomicroscopy were not clearly associated with ocular real-time RT-PCR positivity.