RESUMO

Objetivo: Avaliar a presença de RNA de coronavírus 2 causador de síndrome respiratória aguda grave (SARS-CoV-2) na superfície ocular de indivíduos clinicamente suspeitos com COVID-19 e determinar a precisão de diferentes abordagens de testes moleculares na superfície ocular com base no status de positividade do RT-qPCR de nasofaringe para COVID-19.
Métodos: 152 indivíduos com sintomas suspeitos para a COVID-19 foram submetidos a coleta de reação em cadeia da polimerase de nasofaringe simultaneamente a duas técnicas diferentes de coleta de filme lacrimal para RT-qPCR: aleatoriamente, um olho com a tira filtro do teste de Schirmer e, o olho contralateral, com citologia (swab) conjuntival no fórnice inferior. Todos os indivíduos foram submetidos à biomicroscopia com lâmpada de fenda.
Resultados: Dos 152 pacientes, 86 (56,6%) tiveram a COVID-19 confirmada por PCR de nasofaringe. Ambas as técnicas de coleta detectaram partículas virais: o teste de Schirmer foi positivo em 16,3% (14/86) e a citologia conjuntival em 17,4% (15/86), sem diferenças estatisticamente significativas. Não houve testes oculares positivos entre aqueles com reação em cadeia da polimerase de nasofaringe negativo. A concordância geral dos testes oculares foi de 92,7% e, em combinação, a sensibilidade aumentaria para 23,2%. Os valores médios do limiar de ciclo nos testes de nasofaringe, Schirmer e citologia conjuntival foram 18,2 ± 5,3, 35,6 ± 1,4 e 36,4 ± 3,9, respectivamente.
Conclusão: Os testes de Schirmer (16,3%) e swab conjuntival (17,4%) foram igualmente capazes de detectar RNA de SARS-CoV-2 na superfície ocular por RT-PCR e demonstraram sensibilidade e especificidade indistintas. A coleta simultânea de amostras ao processamento dos testes de RT-PCR de nasofaringe, Schirmer e citologia (swab) conjuntival demonstraram carga viral significativamente menor em ambas as abordagens da superfície ocular em comparação com o teste de nasofaringe. As manifestações oculares detectadas pela biomicroscopia com lâmpada de fenda não foram claramente associadas à positividade do RT-PCR ocular.

Descritores: COVID19; SARS-CoV-2; Túnica conjuntiva; Lágrimas; Reaçao em cadeia da polimerae via transcriptase reversa; RNA; viral.

ABSTRACT

Purpose: This study aimed to evaluate the pre-sence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in the ocular surface of individuals clinically suspected of coronavirus disease 2019 (COVID-19) and determine the accuracy of different approaches of molecular testing on the ocular surface based on the nasopharyngeal positivity status for COVID-19.
Methods: A total of 152 individuals with suspected COVID-19 symptoms who simultaneously underwent nasopharyngeal and two different tear film collection techniques for quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) were included. Tears were collected and randomized: one eye had the filter strip for the Schirmer test and the contralateral eye had conjunctival swab/cytology in the inferior fornix. All patients underwent slit lamp biomicroscopy. The accuracy of various ocular surface collection techniques used for the detection of SARS-CoV-2 RNA was determined.
Results: Of the 152 patients enrolled in the study, 86 (56.6%) had COVID-19 confirmed by nasopharyngeal PCR. Both tear film collection techniques detected viral particles: the Schirmer test was positive in 16.3% (14/86) and the conjunctival swab/cytology in 17.4% (15/86), with no statistically significant differences. No positive ocular tests were found among those with negative nasopharyngeal PCR tests. The overall agreement of the ocular tests was 92.7%, and in combination, the sensitivity would increase to 23.2%. The mean cycle threshold values in the nasopharyngeal, Schirmer, and conjunctival swab/cytology tests were 18.2 ± 5.3, 35.6 ± 1.4, and 36.4 ± 3.9, respectively. Compared with the nasopharyngeal test, the Schirmer (p=0.001) and conjunctival swab/cytology (p<0.001) tests had significantly different Ct values.
Conclusion: The Schirmer (16.3%) and conjunctival swab (17.4%) tests were comparably capable of detecting SARS-CoV-2 RNA in the ocular surface by RT-PCR accurately based on nasopharyngeal status and demonstrated indistinct sensitivity and specificity. Simultaneous specimen sampling and processing from the nasopharyngeal, Schirmer, and conjunctival swab/cytology tests demonstrated significantly lower viral load in both ocular surface approaches than in the nasopharyngeal test. Ocular manifestations detected by slit lamp biomicroscopy were not associated with ocular RT-PCR positivity.

Keywords: COVID-19; SARS-CoV-2; Conjunctiva; Tears; Reverse transcriptase polymerase chain reaction; RNA; viral.

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