Use of Schirmer strips and conjunctival swabs for virus detection on the ocular surface of adults: a scoping review

Sabage, Luís Expedito; Mazzo, Alessandra; Sabage, Josmar; Olivo, Taylor Endrigo Toscano; Santos, Carlos; Lourençone, Luiz Fernando Manzoni

doi:10.5935/0004-2749.20230032

Cited by 2 publications

(3 citation statements)

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“…Moreover, respiratory sample collection can cause discomfort and pain to patients and carries a high risk of virus transmission to health care workers. Recently, Sabage et al proposed the use of Schirmer strips and conjunctival swabs as methods of tear sample collection for molecular testing [ 8 ]. Beltram et al observed that Schirmer strip wetness has a strong influence on the amount of tear volume absorbed and the volume recovered from these strips [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

IgA-Based Secretory Response in Tears of COVID-19 Patients: A Potential Biomarker of Pro-Inflammatory State in Course of SARS-CoV-2 Infection

et al. 2022

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Mucosal immunity, including secretory IgA (sIgA), plays an important role in the early defence against SARS-CoV-2 infection. However, a comprehensive evaluation of the local immune response in tears in relation to blood antibody reservoirs has not yet been conducted. A total of 179 symptomatic laboratory-confirmed COVID-19 patients were included in this single-centre study. Conjunctival swabs were analysed by a reverse transcription polymerase chain reaction for the detection of SARS-CoV-2 RNA. In parallel, tear samples collected by Schirmer test strips and plasma samples were analysed by ELISA to detect anti-S1 IgA levels. The concentrations of selected inflammatory cytokines in tears were determined by a magnetic bead assay. Anti-SARS-CoV-2 sIgA was present in the tears of 81 (45.25%) confirmed COVID-19 patients, and the tear IgA levels were correlated with the plasma IgA levels (Rs = +0.29, p = 0.0003). SARS-CoV-2 RNA in the conjunctival sac was identified in 18 COVID-19 patients (10%). Positive correlations between the tear IgA level and the concentrations of several cytokines TNF-α (Rs = +0.23, p = 0.002), IL-1β (Rs = +0.25, p < 0.001), IL-2 (Rs = +0.20, p = 0.007), IL-4 (Rs = +0.16, p = 0.04), IL-5 (Rs = +0.36, p < 0.001), IL-6 (Rs = +0.32, p < 0.001), IL-8 (Rs = +0.31, p < 0.001), VEGF (Rs = +0.25, p < 0.001) and GM-CSF (Rs = +0.27, p < 0.001) were also found. Quantitative tear film-based sIgA could potentially serve as a rapid and easily accessible biomarker of external mucosal immunity to SARS-CoV-2. The concentration of sIgA is directly related to individual host immune responses to SARS-CoV-2 infection.

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Section: Introductionmentioning

confidence: 99%

IgA-Based Secretory Response in Tears of COVID-19 Patients: A Potential Biomarker of Pro-Inflammatory State in Course of SARS-CoV-2 Infection

et al. 2022

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“…Angiotensin Converting Enzyme 2 (ACE2) and Transmembrane Serine Protease 2 (TMPRSS2), the key viral receptors for SARS-CoV-2 infection, are present on the ocular surface consisting of the cornea, conjunctiva, and limbus [ 9 ]. Although it is still unclear if these ocular surface receptors are sufficient to mediate clinical viral entry, there is evidence that the virus could be detected on the ocular surface, hence, tears may transmit the disease [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…There are several methods to detect viruses on the ocular surface, with the most common being conjunctival swab (CS) sample collection followed by Polymerase Chain Reaction (PCR) or Reverse Transcription PCR (RT-PCR) analysis. Schirmer strips (SS) have shown different detection rates for different viruses because of how capillary flow dynamics, fluid viscosity, and gravity may affect the transfer of viral particles from tears to the filter paper [ 10 , 11 ]. Ocular surface samples collected by these two methods have different sample compositions: CS samples are composed of tears, cells, and fluids dispersed in the conjunctival sac, while SS samples consist of the substances and cells dissolved in tears [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Conjunctival Swabs Reveal Higher Detection Rate Compared to Schirmer Strips for SARS-CoV-2 RNA Detection in Tears of Hospitalized COVID-19 Patients

Sabage

Sun

Wolf

et al. 2022

JCM

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Purpose: To determine the prevalence of SARS-CoV-2 in tear samples and to investigate whether it correlates with ocular findings and patients’ prognosis in Brazil. Methods: Tears were collected using Schirmer strips (SS) and conjunctival swabs (CS) from patients hospitalized with laboratory-confirmed SARS-CoV-2 infection. Samples were analyzed using qRT-PCR. Demographic and clinical data, ocular symptoms, and Schirmer tests (ST) were collected from patients. Charlson Comorbidity Index (CCI) was used to rate comorbidities, and patients were monitored until hospital discharge or death. Results: There were 61 hospitalized patients, 33 of which were diagnosed with COVID-19. Within the confirmed COVID-19 patients, SARS-CoV-2 was detected in 18.2% (n = 6) of CS and 12.1% (n = 4) of SS samples. Subjective and objective parameters for dry eye syndrome (e.g., ST COVID-19: 8.3 ± 6.4mm, non-COVID-19: 8.9 ± 6.6mm, p > 0.05) were comparable between COVID-19 (n = 33) and non-COVID-19 patients (n = 28). Among the 16 COVID-19 patients exhibiting ocular symptoms, only tearing was reported significantly more frequently when tear samples were positive for SARS-CoV-2 (p < 0.05). Strikingly, patients whose tears tested positive for SARS-CoV-2 had significantly inferior CCI (pos.: 34.0 ± 31.8%, neg.: 67.6 ± 36.4%, p < 0.05) and higher mortality rates (pos.: 50.0%, neg.: 7.4%, p < 0.01). Conclusions: SARS-CoV-2 was detected with a prevalence of 18.2% on the ocular surface. Decreased CCI and increased mortality rate in the positive tear group suggests that viral detection may relate to prognosis and highlight the need of personal protective measures for healthcare professionals. Most of the patients, regardless of COVID-19 diagnosis, had low tear production and eye discomfort, possibly pointing to the need for artificial tear use during hospitalization.

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Use of Schirmer strips and conjunctival swabs for virus detection on the ocular surface of adults: a scoping review

Cited by 2 publications

References 0 publications

IgA-Based Secretory Response in Tears of COVID-19 Patients: A Potential Biomarker of Pro-Inflammatory State in Course of SARS-CoV-2 Infection

IgA-Based Secretory Response in Tears of COVID-19 Patients: A Potential Biomarker of Pro-Inflammatory State in Course of SARS-CoV-2 Infection

Conjunctival Swabs Reveal Higher Detection Rate Compared to Schirmer Strips for SARS-CoV-2 RNA Detection in Tears of Hospitalized COVID-19 Patients

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