Relations between the ocular surface and SARS-CoV-2 / Relações entre superfície ocular e SARS-CoV-2

ABSTRACT Introduction: The SARS-CoV-2 pandemic has been a major challenge for the international scientific community. Since its inception, studies aiming to describe pathophysiological aspects and clinical manifestations of the disease have been conducted, raising hypotheses and confirming possible associations. One aspect of this scientific medical production is the role of the ocular surface as a means of transmission and clinical presentation of viral syndrome. Objectives: To analyze the role of the ocular surface in transmission, pathophysiology, and clinical manifestations of SARS-CoV-2, by means of a systematic review. Methods: The search was carried out in three databases: Cochrane, PubMed Central Journals and MEDLINE, using the following descriptors: "COVID-19, ophthalmology". The filters last five years and studies on humans resulted in 32 studies; in that 12 were excluded for not meeting the purpose of the study. Results: There are still few published studies on the relation between SARS-CoV-2 and the ocular route. Most studies showed an association between the presence of nonspecific ocular manifestations and infection by the new coronavirus, with limitations in the number of patients analyzed and the methodology adopted. Hypotheses about the pathophysiological role are largely anchored in the association of SARS-CoV and the ocular surface evaluated in the past. Comments: The results found are still not sufficient to confirm the role of the ocular surface in the pathophysiology of the disease. Most of these preliminary studies are of considerable importance in raising hypotheses based on the medical analysis of the patients studied. However, larger studies with standardized methodology for diagnostic protocol and laboratory analysis of the individuals assessed are required.

RESUMO Introdução: A pandemia da SARS-CoV-2 tem sido um grande desafio para a comunidade científica internacional. Desde seu surgimento, estudos com a intenção de descrever os aspectos fisiopatológicos e as manifestações clínicas da doença vêm sendo conduzidos, levantando hipóteses e confirmando possíveis associações. Um dos temas dessa produção médica científica é o papel da superfície ocular como meio de transmissão e apresentação clínica da síndrome viral. Objetivo: Analisar o papel da superfície ocular na transmissão, na fisiopatologia e nas manifestações clínicas de SARS-CoV-2, através de uma revisão sistemática. Realizou-se a busca em três bancos de dados Cochrane Database, PubMed® e MEDLINE®, utilizando os descritores "COVID-19 e ophthalmology". Foram definidos como filtros o artigo ter sido publicado nos últimos 5 anos e estudo realizado em humanos, tendo sido encontrados 32 artigos. Destes, foram excluídos 12 por não corresponderem ao objetivo do estudo. Resultados: Ainda são poucos os estudos publicados sobre a relação entre o coronavírus 2 da síndrome respiratória aguda grave (SARS-CoV-2) e a via ocular. A maioria dos estudos mostrou associação entre a presença de manifestações oculares inespecíficas e a infecção pelo novo coronavírus, com limitações no número de pacientes analisados e na metodologia adotada. Hipóteses sobre o papel fisiopatológico se ancoram, em grande parte, na associação estudada entre o SARS-CoV-2 e a superfície ocular no passado. Comentários: Os resultados encontrados ainda não são suficientes para confirmar o papel da superfície ocular na fisiopatologia da doença. Grande parte desses estudos preliminares têm importância considerável ao levantar hipóteses baseadas na análise clínica dos pacientes estudados. No entanto, são necessários estudos maiores e com metodologia padronizada para protocolo diagnóstico e análise laboratorial dos indivíduos avaliados.

The COVID-19 Pandemic from an Ophthalmologist's Perspective.

The current coronavirus disease 2019 (COVID-19) pandemic is rapidly spreading around the world. The first doctor to report this new disease was an ophthalmologist: this exemplifies the role of ophthalmologists in an infectious disease pandemic. Here we review how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects the eye and discuss implications for ophthalmologists.

Characterization of SARS-CoV-2 Entry Factors' Expression in Corneal and Limbal Tissues of Adult Human Donors Aged from 58 to 85.

Purpose: Recent studies have shown the presence of SARS-CoV-2 entry factors on the ocular surface, identifying the eye as an additional entry route for the virus. Moreover, the coexpression of angiotensin-converting enzyme 2 (ACE2) with other SARS-CoV-2 entry factors [transmembrane protease serine 2 (TMPRSS2), transmembrane protease serine 4 (TMPRSS4), and dipeptidyl peptidase-4 (DPP4)] facilitates the virus infection. Methods: Here, we performed a study over 10 adult corneal and limbal tissues from human donors, both male and female between 58 and 85 years of age. Some of the main virus entry factors were analyzed and their expression was quantified and correlated with the age and sex of the donors through western blot. The receptors' localization was investigated through immunofluorescence. Results: Immunofluorescence confirmed the localization of ACE2 and TMPRSS2 on the ocular surface and showed, for the first time, the localization of TMPRSS4 and DPP4 in limbal and corneal epithelial superficial cells. The quantitative analysis showed that the expression of SARS-CoV-2 entry factors on corneal and limbal cells is likely to be modulated in an age-dependent manner, in agreement with the increased susceptibility to COVID-19 in the elderly. Moreover, we found a relationship between the expression of TMPRSS proteases with the activation state of limbal cells in 80-year-old donors. Conclusion: This study provides information on the expression of SARS-CoV-2 entry factors on the ocular surface of 10 adult human donors and is a first observation of a possible age-dependent modulation on corneal and limbal tissues. Our data pave the way to further investigate the susceptibility to the infection through the ocular surface in the elderly.

Clinical Utility of COVID-19 Real Time-Polymerase Chain Reaction Testing of Ocular Tissues of Non-COVID-19 Cornea Donors Deemed Suitable for Corneal Retrieval and Transplantation.

PURPOSE: The purpose of this study was to evaluate the prevalence of SARS-CoV-2 in human postmortem ocular tissues of asymptomatic donors and its implications on our eye banking protocols. METHODS: The expression of SARS-CoV-2 RNA was assessed by reverse transcription-polymerase chain reaction in corneal rims and conjunctival tissues from 100 donors who were found suitable for transplantation as per the donor screening guidelines of the Global Alliance of Eye Bank Associations. The donor's clinical history and cause of death were assessed for secondary analysis. RESULTS: Of 200 ocular tissues (100 corneal and 100 conjunctival) from the same 1 eye of 100 surgical-intended donors, between September 2020 and April 2021, the overall positivity rate for SARS-CoV-2 was ∼1% (2/200). Both the ocular samples that tested positive were conjunctival biopsies (2/100, 2%), whereas corneal samples were negative (0/100, 0%) in both donors. The causes of donor death were trauma in 51 donors, suicide in 33, cardiac arrest in 7, electric shock in 5, metabolic cause in 2, malignancy in 1, and snake bite in 1. None of the donors had a medical history suggestive of COVID infection or possible contact. None of the recipients from the donors were reported to have any systemic adverse event after keratoplasty until the follow-up of 6 weeks. CONCLUSIONS: The overall prevalence of SARS-CoV-2 was 1% (2% for conjunctival and 0% for corneal samples, P value = 0.5) in the donors who were found suitable for cornea recovery and transplantation. The findings of exceptionally low positive rates in our samples validate the criticality of history-based donor screening and do not support the necessity of postmortem PCR testing as a criterion for procurement and subsequent use for corneal transplantation.

Viral S protein histochemistry reveals few potential SARS-CoV-2 entry sites in human ocular tissues.

Despite the reported low expression of the primary SARS-CoV-2 receptor ACE2 in distinct ocular tissues, some clinical evidence suggests that SARS-CoV-2 can infect the eye. In this study, we explored potential entry sites for SARS-CoV-2 by viral S protein histochemistry on various ocular tissues and compared the staining patterns with RNA and protein expression of TMPRSS2 and ACE2. Potential viral entry sites were investigated by histochemistry using tagged recombinant viral S protein on 52 ocular tissue samples including specimens of the cornea, conjunctiva, lid margin, lacrimal gland tissue, retina, choroid, and RPE. In addition, ACE2 and TMPRSS2 immunohistochemistry were performed on the same ocular tissue, each with distinct antibodies binding to different epitopes. Lung tissue samples were used as positive controls. Finally, bulk RNA sequencing (RNA-Seq) was used to determine the expression of ACE2 and its auxiliary factors in the tissues mentioned above. S protein histochemistry revealed a positive staining in lung tissue but absent staining in the cornea, the conjunctiva, eye lid samples, the lacrimal glands, the retina and the optic nerve which was supported by hardly any immunoreactivity for ACE2 and TMPRSS2 and scarce ACE2 and TMPRSS2 RNA expression. Negligible staining with antibodies targeting ACE2 or TMPRSS2 was seen in the main and accessory lacrimal glands. In contrast, ocular staining (S protein, ACE2, TMPRSS2) was distinctly present in pigmented cells of the RPE and choroid, as well as in the ciliary body and the iris stroma. S protein histochemistry revealed hardly any SARS-CoV-2 entry sites in all ocular tissues examined. Similarly, no significant ACE2 or TMPRSS2 expression was found in extra- and intraocular tissue. While this study suggest a rather low risk of ocular infection with SARS-CoV-2, it should be noted, that potential viral entry sites may increase in response to inflammation or in certain disease states.

Novel Insights into the Transmission of SARS-CoV-2 Through the Ocular Surface and its Detection in Tears and Conjunctival Secretions: A Review.

SARS-CoV-2 is a highly transmissible virus that spreads mainly via person-to-person contact through respiratory droplets, or through contact with contaminated objects or surfaces from an infected person. At present we are passing through a phase of slow and painful understanding of the origin, epidemiological profile, clinical spectrum, and risk profile of the virus. To the best of our knowledge there is only limited and contradictory evidence concerning SARS-CoV-2 transmission through other routes. Importantly, the eye may constitute not only a potential site of virus replication but also an alternative transmission route of the virus from the ocular surface to the respiratory and gastrointestinal tract. It is therefore imperative to gain a better insight into the potential ophthalmological transmission route of the virus and establish directions on best practice and future models of care for ophthalmological patients. This review article critically evaluates available evidence on the ophthalmological mode of viral transmission and the value of earlier identification of the virus on the eye. More evidence is urgently needed to better evaluate the need for protective measures and reliable ocular diagnostic tests to diminish further pandemic spread.

COVID-19 Ocular Manifestations in the Early Phase of Disease.

Purpose: To evaluate and establishe the number of patients with ocular manifestations in the early phase of systemic COVID-19 infection.Methods: A cross-sectional study was performed in a COVID-19 referral center regarding ocular findings in patients with COVID-19 in the first few days of the disease. The patients were submitted to a clinical examination, an ophthalmic exam and a RT-PCR for SARS-COV-2.Results: Out of 1740 patients, we reported 108 patients with ocular manifestations. Forty-nine with markedly conjunctivitis had conjunctival swab positive for SARS-COV-2, four of them developed keratitis. There were mostly no evidence of retinopathy nor decrease in visual acuity. They had no marked clinical symptoms, which can contribute and demonstrate that the virus may cause ocular disease as an only finding or in the very early stage of the infection.Conclusion: Patients were in the first days of COVID-19 infection, presented ocular manifestations suggested to be related to the virus and need to be aware of the pathways of transmissions.

An Eye on COVID-19: A Meta-analysis of Positive Conjunctival Reverse Transcriptase-Polymerase Chain Reaction and SARS-CoV-2 Conjunctivitis Prevalence.

SIGNIFICANCE: This analysis and review demonstrate that, although emerging data indicate that the prevalence of severe acute respiratory coronavirus 2 (SARS-CoV-2) on the ocular surface and coronavirus disease 2019 (COVID-19) conjunctivitis is rare, the ocular surface remains of interest as a potential inoculation and transmission site for SARS-CoV-2. Continued safety precautions should be taken as more data become available.COVID-19, caused by SARS-CoV-2, is a novel, global pandemic that has infected millions and, up to this point, caused more than two million fatalities worldwide. The ocular surface has become of interest as a possible vector for transmission by acting as a direct inoculation site, being a conduit for the virus into the respiratory system or as a method of transmission from potentially infected conjunctiva or tears. The components necessary for SARS-CoV-2 to theoretically infect ocular tissues are present: binding receptors (angiotensin-converting enzyme 2 and cluster of differentiation 147) and mechanisms for cell entry (transmembrane protease serine 2 and cathepsin L). This meta-analysis of COVID-19 prevalence data indicates that SARS-CoV-2 RNA has been infrequently found in conjunctival samples when tested with reverse transcriptase-polymerase chain reaction. This review estimates the prevalence of SARS-CoV-2 on the ocular surface and prevalence of conjunctivitis in patients with laboratory-confirmed COVID-19. There is much to be learned regarding ocular tropism of SARS-CoV-2.

The Presence of SARS-CoV-2 in Conjunctival Secretions of COVID-19 Patients.

Purpose: To evaluate the presence of SARS-CoV-2 in conjunctival secretions of COVID-19 patients.Material and Methods: In this retrospective study, the records were examined of patients who were treated in the hospital with the diagnosis of COVID-19 between March-May 2020 and were referred to the eye clinic due to ocular symptoms. Conjunctival swabs from both confirmed and suspected COVID-19 cases during hospitalization were analyzed.Results: A total of 35 patients (22 suspected, 13 laboratory-confirmed COVID-19) were referred to the eye clinic. Conjunctival swab samples from 3 patients yielded positive PCR results. These three patients were being treated in the intensive care unit, and all were suspected COVID-19 patients.Conclusion: SARS-CoV-2 may be detected in patients with suspected COVID-19. Even with conjunctivitis findings, SARS-CoV-2 may not be detected in most conjunctiva swab samples of COVID-19 patients.

The comprehensive clinic, laboratory, and instrumental evaluation of children with COVID-19: A 6-months prospective study.

OBJECTIVES: To perform a comprehensive clinic, laboratory, and instrumental evaluation of children affected by coronavirus disease (COVID-19). METHODS: Children with a positive result of nasopharyngeal swab for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) underwent laboratory tests, anal and conjunctival swab, electrocardiography, lung, abdomen, and cardiac ultrasound. Twenty-four-hour ambulatory blood pressure monitoring was performed if abnormal basal blood pressure. Patients were followed-up for 6 months. RESULTS: Three hundred and sixteen children were evaluated; 15 were finally included. Confirmed family member SARS-CoV-2 infection was present in all. Twenty-seven percent were asymptomatic. Anal and conjunctival swabs tests resulted negative in all. Patients with lower body mass index (BMI) presented significantly higher viral loads. Main laboratory abnormalities were: lactate dehydrogenase increasing (73%), low vitamin D levels (87%), hematuria (33%), proteinuria (26%), renal hyperfiltration (33%), and hypofiltration (13%). Two of the patients with hyperfiltration exhibited high blood pressure levels at diagnosis, and persistence of prehypertension at 6-month follow-up. No abnormalities were seen at ultrasound, excepting for one patient who exhibited B-lines at lung sonography. Immunoglobulin G seroconversion was observed in all at 1-month. CONCLUSIONS: Our study confirm that intra-family transmission is important. The significant higher viral loads recorded among patients with lower BMI, together with low vitamin D levels, support the impact of nutritional status on immune system. Renal involvement is frequent even among children with mild COVID-19, therefore prompt evaluation and identification of patients with reduced renal function reserve would allow a better stratification and management of patients. Seroconversion occurs also in asymptomatic children, with no differences in antibodies titer according to age, sex and clinical manifestations.

An Update on COVID-19 Related Ophthalmic Manifestations.

Purpose: To summarize ophthalmic manifestations of coronavirus disease (COVID-19) reported in the literature thus far.Methods: The PubMed database was systematically searched through October 24, 2020, to identify relevant articles using the following search terms: ("COVID-19" OR "SARS-CoV-2") AND ("eye" OR "ophthalmology" OR "retina" OR "retinal findings" OR "cornea" OR "conjunctiva"). Only articles published in English were included in this review.Results: The reported prevalence of ophthalmic manifestations is generally low, but correlates positively with the severity of the disease. Most commonly reported ocular manifestations are conjunctivitis, conjunctival hyperemia and chemosis. Retinal findings include microhemorrhages and flame-shaped hemorrhages, cotton wool spots, dilated veins, and tortuous vessels.Conclusion: Considering the COVID-19 cases have reached pandemic dimensions and are surging, yet again, it is of utmost importance to determine its ophthalmic manifestations and prevent their vision threatening complications. Further studies are warranted to establish whether the retinal findings appear due to the COVID-19 or are an incidental finding in patients with a preexisting diabetic or hypertensive retinopathy.

Comparison of the simultaneous conjunctiva and oropharynx-nasopharynx swab results in patients applying to the SARS-CoV-2 outpatient clinic for the first time.

The aim is to comparatively evaluate the results of simultaneous conjunctiva and oropharynx-nasopharynx (ONP) swabs in patients who had presented to the outpatient department with a suspicion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). An ONP sample was obtained following bilateral conjunctiva swabs in 85 subjects with a contact history or symptoms but unknown SARS-CoV-2 status and with no ocular symptoms or findings. The results were evaluated according to the patient's symptoms and how the swab was taken. The conjunctiva swab was positive in 29 (34.1%) cases and the ONP swab in 20 (23.5%) cases. Both methods produced positive results in 11 (14.1%) cases. The mean cycle threshold (Ct ) value was 30.15 ± 3.41 in symptomatic cases and 33.62 ± 1.76 in asymptomatic cases (p = .008). The mean Ct value was 24.37 ± 3.48 when only the ONP swab was positive and 31.22 ± 1.99 when only the conjunctiva swab was positive. In cases that were positive by both methods, the mean Ct value was 25.21 ± 4.94 for the ONP swab and 30.29 ± 5.05 for the conjunctiva swab. We found higher SARS-CoV-2 detection rates with the conjunctiva swab than the ONP swab in cases with unknown SARS-CoV-2 status in the early period. In addition, the conjunctival viral load seemed to be higher in symptomatic cases than in asymptomatic cases. We, therefore, believe a conjunctiva swab could be an alternative method to detect SARS-CoV-2 at the time of the first presentation to the outpatient department.

In the eye of the storm: SARS-CoV-2 infection and replication at the ocular surface?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first emerged in December 2019 and spread quickly causing the coronavirus disease 2019 (COVID-19) pandemic. Recent single cell RNA-Seq analyses have shown the presence of SARS-CoV-2 entry factors in the human corneal, limbal, and conjunctival superficial epithelium, leading to suggestions that the human ocular surface may serve as an additional entry gateway and infection hub for SARS-CoV-2. In this article, we review the ocular clinical presentations of COVID-19 and the features of the ocular surface that may underline the overall low ocular SARS-CoV-2 infection. We critically evaluate the studies performed in nonhuman primates, ex vivo organ culture ocular models, stem cell derived eye organoids and the differences in infection efficiency observed in different parts of human ocular surface epithelium. Finally, we highlight the additional work that needs to be carried out to understand the immune response of the ocular surface to SARS-CoV-2 infection, which can be translated into prophylactic treatments that may be applied to other organ systems.

Evaluation of Nasopharyngeal and Conjunctival Swab Samples of Hospitalised Patients with Confirmed COVID-19.

PURPOSE: To evaluate the results of conjunctival and nasopharyngeal swab tests in patients with confirmed COVID-19. METHODS: This prospective study included 45 patients who were hospitalized for confirmed COVID-19. Nasopharyngeal swab samples were obtained from the patients before hospitalization. Only one eye of each patient was randomly selected for-conjunctival sampling. All participants underwent a complete slit-lamp examination. Conjunctival and nasopharyngeal swab samples were analyzed by reversetranscriptase-polymerase-chain reaction (RT-PCR). RESULTS: Twenty seven (60%) of the patients were male and 18 (40%) were female. Conjunctival swab was positive in only one (2.22%) patient. None of the COVID-19 patients showed ocular changes and symptoms. There were no abnormalities of the ocular surface, anterior chamber or posterior segment at slit-lamp examination. CONCLUSIONS: The RT-PCR was not high positive in the conjunctiva as in nasopharyngeal swabs. Ocular changes were not common in COVID-19 patients.

SARS-CoV-2 on Ocular Surfaces in a Cohort of Patients With COVID-19 From the Lombardy Region, Italy.

Importance: Since February 2020, coronavirus disease 2019 (COVID-19) has spread rapidly all over the world, with an epidemiological cluster in Lombardy, Italy. The viral communicability may be mediated by various body fluids, but insufficient information is available on the presence of the virus in human tears. Objectives: To investigate the rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in tears collected from patients with COVID-19 by means of real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) assay and to assess the association of virus presence with concomitant clinical conditions. Design, Setting, and Participants: Cross-sectional study conducted between April 9 and May 5, 2020. The setting was intensive care units at Azienda Socio-Sanitaria Territoriale (ASST) Sette-Laghi Hospital, University of Insubria, in Varese, Lombardy, Italy. A conjunctival swab was performed in 91 patients hospitalized for COVID-19, which was clinically diagnosed by rRT-PCR assay on nasopharyngeal swabs and by radiological imaging. Conjunctival swabs from 17 additional healthy volunteer participants with no symptoms of COVID-19 were examined to evaluate the availability and applicability of the conjunctival swab test. Exposure: SARS-CoV-2 detection by means of rRT-PCR assay performed on the collected samples obtained by conjunctival swabs. Main Outcomes and Measures: Conjunctival swab and nasopharyngeal swab results are reported, as well as demographic and clinical data. Results: A total of 108 participants (mean [SD] age, 58.7 [14.2] years; 55 female and 53 male) were tested for SARS-CoV-2 using rRT-PCR assay, including 91 patients hospitalized with COVID-19 and 17 were healthy volunteers. SARS-CoV-2 was found on the ocular surface in 52 of 91 patients with COVID-19 (57.1%; 95% CI, 46.3%-67.5%), with a wide variability in the mean viral load from both eyes. Among a subset of 41 patients, concordance of 63.0% (95% CI, 41.0%-81.0%) was found between positive conjunctival and nasopharyngeal swab test results when performed within 2 days of each other. In 17 of these patients, nasopharyngeal swab results were negative for SARS-CoV-2. In 10 of these 17 patients, conjunctival swab results were positive for the virus. Conclusions and Relevance: In this study, SARS-CoV-2 RNA was found on the ocular surface in a large part of this cohort of patients with COVID-19, although the infectivity of this material could not be determined. Because patients may have positive test results with a conjunctival swab and negative results with a nasopharyngeal swab, use of the slightly invasive conjunctival swab may be considered as a supplementary diagnostic test.

Implications of COVID-19 for Ophthalmologists.

PURPOSE: To describe and explain the implications of coronavirus disease 2019 (COVID-19) for ophthalmologists considering the rapid developments in our understanding of the virology, transmission, and ocular involvement. DESIGN: Evidence-based perspective. METHODS: Review and synthesis of pertinent literature. RESULTS: Retrospective studies highlight that <1% of patients display COVID-19-related conjunctivitis. However, prospective studies suggest the rate is higher (~6%). Viral RNA has been identified in tears and conjunctival secretions in patients with active conjunctivitis as well as asymptomatic cases. Overall, conjunctival swabs are positive in 2.5%. Samples taken earlier in the disease course are more likely to demonstrate positive virus. Viral transmission through ocular tissues has not been substantiated. Ophthalmologists are in the high-risk category for COVID-19 infection for several reasons: high-volume clinics, close proximity with patients, equipment-intense clinics, and direct contact with patients' conjunctival mucosal surfaces. COVID-19 is predominantly contracted through direct or airborne transmission by inhalation of respiratory droplets. Evidence that aerosol transmission occurs is increasing in particularly prolonged exposure to high concentrations in a relatively closed environment. Based on the current evidence, ophthalmologists should consider measures that include social distancing, wearing masks, sterilization techniques, and managing clinic volumes. CONCLUSIONS: A major challenge to containing COVID-19 is that many infected people are asymptomatic. Droplet spread, contaminated environmental surfaces, and shared medical devices are areas that require management by ophthalmologists. More studies are required to explore the role of the conjunctiva and ocular tissues in the transmission of disease.

A Patient With Bilateral Conjunctivitis Positive for SARS-CoV-2 RNA in a Conjunctival Sample.

PURPOSE: To present a patient with bilateral conjunctivitis, testing positive for viral RNA of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in both nasopharyngeal and conjunctival samples. METHODS: A 40-year-old man with bilateral acute conjunctivitis and suspicious signs of coronavirus disease 2019 (COVID-19) presented to the hospital. A detailed ophthalmic examination was performed. Samples obtained from conjunctival and nasopharyngeal swabs were tested by reverse transcription PCR (RT-PCR) for the detection of SARS-CoV-2 virus. Ocular findings and duration of the presence of viral RNA in the conjunctival specimens were evaluated at follow-up visits. RESULTS: Slit-lamp biomicroscopy revealed bilateral acute follicular conjunctivitis. The RT-PCR assay demonstrated the presence of viral RNA in the nasopharyngeal and conjunctival specimens at the initial visit and at the 4-day follow-up. Conjunctivitis findings were decreased after 4 days and recovered completely without any sequelae within10 days. The PCR results of both nasopharyngeal and conjunctiva specimens were negative for the viral RNA at 10 days. CONCLUSIONS: Bilateral conjunctivitis is rare in patients infected with COVID-19. Although it is difficult to detect viral RNA from conjunctival swabs, conjunctival secretions may be a source of contamination, and protective measures must be taken.

Absence of Severe Acute Respiratory Syndrome-Coronavirus-2 RNA in Human Corneal Tissues.

PURPOSE: To examine corneal tissue for severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) positivity regarding implications for tissue procurement, processing, corneal transplantation, and ocular surgery on healthy patients. We performed quantitative reverse transcription-polymerase chain reaction qRT-PCR-testing for SARS-CoV-2 RNA on corneal stroma and endothelium, bulbar conjunctiva, conjunctival fluid swabs, anterior chamber fluid, and corneal epithelium of coronavirus disease 2019 (COVID-19) postmortem donors. METHODS: Included in this study were 10 bulbi of 5 COVID-19 patients who died because of respiratory insufficiency. Informed consent and institutional review board approval was obtained before this study (241/2020BO2). SARS-CoV-2 was detected by using a pharyngeal swab and bronchoalveolar lavage. Tissue procurement and tissue preparation were performed with personal protective equipment (PPE) and the necessary protective measures. qRT-PCR-testing was performed for each of the abovementioned tissues and intraocular fluids. RESULTS: The qRT-PCRs yielded no viral RNA in the following ocular tissues and intraocular fluid: corneal stroma and endothelium, bulbar-limbal conjunctiva, conjunctival fluid swabs, anterior chamber fluid, and corneal epithelium. CONCLUSIONS: In this study, no SARS-CoV-2-RNA was detected in conjunctiva, anterior chamber fluid, and corneal tissues (endothelium, stroma, and epithelium) of COVID-19 donors. This implicates that the risk for SARS-CoV-2 infection using corneal or conjunctival tissue is very low. However, further studies on a higher number of COVID-19 patients are necessary to confirm these results. This might be of high importance for donor tissue procurement, processing, and corneal transplantation.