SARS-CoV-2 in Conjunctiva and Tears and Ocular Symptoms of Patients with COVID-19

SARS-CoV-2 positivity rates in tear secretions of inpatient COVID-positive individuals in an Indian tertiary care setting

PURPOSE

In the third wave of the coronavirus disease 2019 (COVID-19) pandemic, despite progressive vaccination coverage, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was rapidly spreading and the possibility for ocular transmission of COVID-19 was most relevant. This study aimed to determine the presence of SARS-CoV-2 RNA in tears as detected by real-time polymerase chain reaction (RT-PCR), among individuals who tested COVID-positive during the third wave of the COVID pandemic.

METHODS

Among 90 patients admitted with mild to severe COVID-19 infection (ranging from asymptomatic to severe symptoms), separate conjunctival samples were obtained from both eyes without topical anesthesia taking precautions to avoid contamination. Inferior fornices of the eyes were swept slowly with sterile Dacron swabs for 10 s or until visibly wet. They were inoculated directly in a viral lysis buffer containing carrier RNA and transported to the Virology Laboratory for the detection of SARS-CoV-2 RNA by RT-PCR. Conjunctival swabs were declared positive based on cycle threshold values of <37.

RESULTS

Seven of 180 conjunctival swabs were positive (3.9%). Five patients had unilateral positive and one patient had bilateral positive conjunctival swabs. Thirty-six (40%) patients had their conjunctival swabs taken on the same day of detection of the first positive nasopharyngeal swab, while the rest (54) had their conjunctival swabs taken up to 3 days later. Overall, 20 (22.2%) patients were symptomatic for COVID-19.

CONCLUSION

Considering the contagious nature of SARS-CoV-2 in the third wave, there is a possibility that ocular surface fluid might have been a contributing factor along with other modes of transmission of COVID-19.

Impact of COVID-19 on Ocular Surface Health: Infection Mechanisms, Immune Modulation, and Inflammatory Responses

COVID-19, caused by SARS-CoV-2, has presented formidable challenges to global health since its emergence in late 2019. While primarily known for respiratory symptoms, it can also affect the ocular surface. This review summarizes the effects of SARS-CoV-2 on ocular surface immunity and inflammation, focusing on infection mechanisms, immune responses, and clinical manifestations. Ocular symptoms, though uncommon, include conjunctivitis, dry eye, and blurred vision. SARS-CoV-2 binds to ACE2 receptors in ocular surface epithelial cells, facilitating viral entry, replication, and local dissemination. The innate immune responses involving corneal epithelial cells and immune cells are discussed, alongside mechanisms of antigen presentation and adaptive immunity. The review also examines the roles of cytokines and chemokines in mediating ocular surface inflammation and explores the impact of cytokine storms and chronic inflammation on ocular health. Additionally, the interplay between systemic and ocular immune responses is highlighted, analyzing how systemic COVID-19 inflammation influences ocular surface health. These insights underscore the broader implications of COVID-19 beyond localized ocular infection. By consolidating current findings, this review aims to guide preventive and therapeutic strategies while identifying directions for future research to mitigate the ocular consequences of COVID-19.

The Characteristics of Ocular Findings and the Presence of SARS-CoV-2 in the Tears of Coronavirus Disease 2019 Patients

Purpose The purpose of the study is to observe the characteristics of ocular manifestations in coronavirus disease 2019 (COVID-19) patients and to analyze the presence of severe acute respiratory syndrome coronavirus 2 ribonucleic acid (SARS-CoV-2 RNA) in the tears of patients with moderate-to-severe COVID-19. Material and methods We conducted this prospective cross-sectional study from February to June 2021 at the All India Institute of Medical Sciences, one of the tertiary eye care centers in Nagpur, India. The study included confirmed COVID-19 patients based on real-time reverse transcription-polymerase chain reaction (RT-PCR) nasopharyngeal swabs, whether or not the patients exhibited ocular symptoms. We recorded detailed information regarding the patients' history, including demographic profile, ocular symptoms, systemic symptoms, and radiologic findings. We collected ocular samples within 48 hours of collecting naso-oropharyngeal samples from the patients' eyes. We used conjunctival swabs to obtain tear samples, which we then placed in viral transport media (VTM) for cold chain transportation to the microbiology department. We performed RT-PCR on the tear samples to detect the presence of the SARS-CoV-2 virus. Result We included 40 patients in the study, with 26 (65%) classified as having moderate COVID-19, six (15%) classified as having severe COVID-19, and the remaining having mild COVID-19. Out of the 40 patients, five (12%) tested positive for SARS-CoV-2 in the tear sample using RT-PCR, seven (17%) exhibited ocular signs and symptoms, and only one tested positive for SARS-CoV-2 in their tears. The ocular manifestations observed in COVID-19 patients included dry eye, conjunctivitis (including conjunctival hyperemia and epiphora), and lid edema. Notably, we detected a positive COVID-19 tear sample in patients both with and without ocular symptoms. Conclusion Limited reports have focused on ocular involvement in patients with COVID-19. However, our study demonstrates the detection of SARS-CoV-2 in conjunctival swabs from confirmed COVID-19 patients, albeit with a lower positivity rate. Despite the low prevalence of the virus found in tears, there is a potential risk of transmission through ocular routes. It is noteworthy that we observed a COVID-19-positive tear sample in patients with and without ocular symptoms. Therefore, it is important to consider the possibility of ocular transmission even in the absence of ocular manifestations. Medical personnel should take careful precautions during ocular examinations of patients diagnosed with COVID-19 to minimize the risk of transmission.

Virological and cytological changes in tears and conjunctiva of patients with COVID-19

Purpose

To analyze the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in tears/conjunctival epithelium and assess the cytomorphological changes in the conjunctival epithelium of coronavirus disease 2019 (COVID-19) patients.

Methods

In this pilot study, patients with moderate to severe COVID-19 were recruited from the COVID ward/intensive care unit of the institute. Tears and conjunctival swabs were collected from COVID-19 patients and sent to the virology laboratory for reverse transcription polymerase chain reaction (RT-PCR) testing. Conjunctival swabs were used to prepare smears, which underwent cytological evaluation and immunocytochemistry for SARS-CoV-2 nucleocapsid protein.

Results

Forty-two patients were included. The mean age of participants was 48.61 (range: 5-75) years. Seven (16.6%) patients tested positive for SARS-CoV-2 ribonucleic acid in tears samples, four (9.5%) of which were positive on conjunctival swab by RT-PCR in the first test. Cytomorphological changes were observed significantly more in smears from patients with positive RT-PCR on tear samples, including bi-/multi-nucleation (p = 0.01), chromatin clearing (p = 0.02), and intra-nuclear inclusions (p < 0.001). One case (3.2%) showed immunopositivity for SARS-CoV-2; this patient had severe disease and the lowest Ct values for tear and conjunctival samples among all positive cases.

Conclusion

Conjunctival smears from patients with COVID-19 revealed cytomorphological alterations, even in the absence of clinically significant ocular infection. However, viral proteins were demonstrated within epithelial cells only rarely, suggesting that although the conjunctival epithelium may serve as a portal for entry, viral replication is possibly rare or short-lived.

Detection of coronavirus in tear samples of hospitalized patients with COVID-19

PURPOSE

To assess the presence of viral RNA in conjunctival secretions and tears of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients in terms of a possible ocular transmission route and also to examine whether a difference between the patients with and without ocular surface positivity existed.

METHODS

A prospective cross-sectional study of 70 consecutive patients who were hospitalized in Haseki Training and Research Hospital with SARS-CoV-2 from February 1 to April 1, 2021, was performed. Tears and conjunctival secretions were collected within 24 h of nasopharyngeal sample collection and examined for SARS-CoV-2 using reverse transcription real-time polymerase chain reaction (qPCR). The clinical data, results of blood tests and nasopharyngeal and conjunctival swabs, and CT findings were evaluated for all patients.

RESULTS

Seventy patients (37 males, 33 females) were included in this study. Tear-conjunctival samples from eight patients (11.42%) yielded positive PCR results although these eight patients had no eye symptoms or conjunctivitis. In patients with positive conjunctival PCR results, cycle threshold values for conjunctival samples were higher than those for nasopharyngeal samples. All findings (except gender) were similar between patients with either positive or negative conjunctival swab samples. All patients with positive conjunctival swab samples were male; however, the male ratio in patients with negative conjunctival swab samples was only 46.77%.

CONCLUSION

In our study, the rate of conjunctival swab PCR positivity was 11.42%. It appears that even in the absence of ocular symptoms, SARS-CoV-2 virus may be present on the ocular surface; therefore, the ocular surface may be a significant viral transmission route.

Covid-19 and its relation to the human eye: transmission, infection, and ocular manifestations

BACKGROUND

The world is suffering from a new strain of the coronavirus family-Covid-19. This virus strain affected different organs in the human body with a wide range of mild symptoms and moderate signs to severe and deadly ones. Multiple organs can be infected, and one of these organs is the eye. The eye is a vital organ that consists of vascular tissues and is connected to the respiratory tract through the tears and the nasolacrimal duct.

METHODS

Recent papers and research from PubMed, Researchgate, and Google Scholar were cited and thoroughly discussed. These papers were chosen based on their relevancy, reliability, publication year, published journal, and ease of accessibility to the paper itself.

RESULTS

The theory concluded that the ocular surface might consider a pathway for the virus attack and infection causation through the tears and the angiotensin-converting enzyme 2 located in the eye. This article thoroughly reviewed the history, the existing aspects of Covid-19, the ocular system features, and the claims about the possible involvement of the eye in the virus transmission along with the eye infection. There was no consensus on the eye's involvement theory.

CONCLUSION

The authors highlighted the extra work and research needed to be conducted to prove or deny these claims to provide a better understanding of the immune response of the eye to Covid-19 infection.

Ocular symptoms in COVID-19 infection: a survey study

BACKGROUND

Coronavirus disease 2019 (COVID-19) systemic symptoms and sequelae have been studied extensively, but less is known about the characterization, duration, and long-term sequelae of ocular symptoms associated with COVID-19 infection. The purpose of this study was to analyze the frequency, spectrum, and duration of ocular symptoms in participants with COVID-19 infection treated in inpatient and outpatient settings.

METHODS

A retrospective electronic survey was distributed to NIH employees and the public who reported testing positive for SARS-CoV-2. The anonymous survey collected information on demographics, past ocular history, systemic COVID-19 symptoms, and ocular symptoms.

RESULTS

A total of 229 (21.9% male and 78.1% female, mean age 42.5 ± 13.9) survey responses were included. Ocular symptoms were reported by 165 participants with a mean of 2.31 ± 2.42 symptoms. The most commonly reported ocular symptoms were light sensitivity (31.0%), itchy eyes (24.9%), tearing (24.9%), eye redness (24.5%), and eye pain (24.5%). Participants with ocular symptoms had a higher number of systemic symptoms compared to participants without ocular symptoms (mean 9.17 ± 4.19 vs 6.22 ± 3.63; OR: 1.21; 95% CI: 1.11 - 1.32; p < 0.001). Ocular symptoms were more common in those who reported a past ocular history compared to those who did not (81.8% vs 67.1%; OR: 2.17; 95% CI: 1.08 - 4.37; p = 0.03). Additionally, the onset of ocular symptoms occurred most frequently at the same time as systemic symptoms (47.5%), and 21.8% reported symptoms lasting ≥ 14 days.

CONCLUSIONS

Ocular surface-related symptoms are the most frequent ocular manifestations, and systemic disease severity is associated with the presence of ocular symptoms. Additionally, our results show that ocular symptoms can persist post-COVID-19 infection. Further work is needed to better understand ocular symptoms in COVID-19 and long-term sequelae.

Nanomaterials to combat SARS-CoV-2: Strategies to prevent, diagnose and treat COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the associated coronavirus disease 2019 (COVID-19), which severely affect the respiratory system and several organs and tissues, and may lead to death, have shown how science can respond when challenged by a global emergency, offering as a response a myriad of rapid technological developments. Development of vaccines at lightning speed is one of them. SARS-CoV-2 outbreaks have stressed healthcare systems, questioning patients care by using standard non-adapted therapies and diagnostic tools. In this scenario, nanotechnology has offered new tools, techniques and opportunities for prevention, for rapid, accurate and sensitive diagnosis and treatment of COVID-19. In this review, we focus on the nanotechnological applications and nano-based materials (i.e., personal protective equipment) to combat SARS-CoV-2 transmission, infection, organ damage and for the development of new tools for virosurveillance, diagnose and immune protection by mRNA and other nano-based vaccines. All the nano-based developed tools have allowed a historical, unprecedented, real time epidemiological surveillance and diagnosis of SARS-CoV-2 infection, at community and international levels. The nano-based technology has help to predict and detect how this Sarbecovirus is mutating and the severity of the associated COVID-19 disease, thereby assisting the administration and public health services to make decisions and measures for preparedness against the emerging variants of SARS-CoV-2 and severe or lethal COVID-19.

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

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.

Evaluating Ocular Symptoms and Tear Film Cytokine Profiles in Symptomatic COVID-19 Patients

Background: This study investigated the presence and duration of ophthalmic symptoms in the early phase of COVID-19 to assess the corresponding local immune response on the ocular surface. Methods: The study included data from 180 COVID-19 patients and 160 age-matched healthy controls. The main finding was the occurrence of ophthalmological manifestations at the time of admission to the hospital and during the preceding 7 days. Tear film concentrations of TNF-α, IL-1b, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12 p70, GM-CSF, and IFN-γ were determined by a magnetic bead assay. Results: Among the COVID-19 patients, 12.64% had at least one ocular symptom at the time of admission, and 24.14% had symptoms within the preceding 7 days (p < 0.001 vs. controls). We found that the COVID-19 patients complained more frequently about eye tearing (p = 0.04) and eye pain (p = 0.01) than controls. A multivariate analysis of the patients and controls adjusted for age and sex revealed that COVID-19 was an independent factor associated with higher VEGF and IL-10 tear film concentrations (β = +0.13, p = 0.047 and β = +0.34, p < 0.001, respectively) and lower IL-1β, IL-8, and GM-CSF levels (β = −0.25, p < 0.001; β = −0.18, p = 0.004; and β = −0.82, p = 0.0 respectively). Conclusions: SARS-CoV-2 does not attract a strong local response of the conjunctival immune system; therefore, ophthalmic symptoms may not constitute a substantial element in the clinical picture of novel COVID-19 infection.