Detection of Coronavirus in Tear Samples of Hospitalized Patients With Confirmed SARS-CoV-2 From Oropharyngeal Swabs

Metal-Organic Framework-Based Surface-Enhanced Raman Scattering Sensing Platform for Trace Malondialdehyde Detection in Tears

Disease biomarkers in tears are crucial for clinical diagnosis and health monitoring. However, the limited volume of tear samples, low concentration of tear biomarkers, and complex tear composition present challenges for precise testing. We introduce a spot-on testing platform of metal-organic framework (MOF)-based surface-enhanced Raman scattering (SERS) capillary column, which is capable of target molecules selective separation and enrichment for tear biomarkers in situ detection. It consists of Au nanostars for effective SERS signal and a porous MOF shell for separating impurities through molecular sieving effect. This platform allows for simultaneous collection and detection of tear, capturing the disease biomarker malondialdehyde in tears with a 9.38 × 10-9 mol/L limit of detection. Moreover, we designed a hand-held device based on this tubular SERS sensor, successfully diagnosing patients with dry eye disease. This functional capillary column enables noninvasive and rapid diagnosis of biomarkers in biofluids, providing potential for disease diagnosis and healthcare monitoring.

Dry eye symptoms are prevalent in moderate-severe COVID-19, while SARS-COV-2 presence is higher in mild COVID-19: Possible ocular transmission risk of COVID-19

Purpose

To evaluate the correlation between dry eye symptoms and coronavirus disease 2019 (COVID-19) infection and to assess the real-time reverse transcription-polymerase chain reaction (RT‒PCR) of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) from the conjunctival swab.

Methods

A prospective observational case series study was conducted of all suspected and confirmed COVID-19 patients from Dr. Cipto Mangunkusumo Hospital (RSCM) and the Universitas Indonesia Hospital (RSUI). On the first day of the visit (day 0), systemic clinical symptoms and naso-oropharyngeal (NO) RT‒PCR results will classify all subjects as non-, suspected, or confirmed (mild, moderate, and severe) COVID-19. In all patients, we determined the dry eye symptoms based on the Ocular Surface Disease Index (OSDI) and followed up 7(day 7) and 14 days (day 14) after the first visit. When it was technically possible, we also examined the objective dry eye measurements: tear meniscus height (TMH), noninvasive Keratograph® break-up time (NIKBUT), and ocular redness. Additionally, we took conjunctival swab samples for SARS-CoV-2 RT-PCR in all patients.

Results

The OSDI scores for 157 patients decreased across days 0, 7, and 14 (median (interquartile range): 2.3 (0-8), 0 (0-3), and 0 (0-0), p value < 0.0001 (D0 vs D14). The moderate-severe COVID-19 group had a higher OSDI score than the other groups at median D0 (15.6 vs 0-2.3), p value < 0.0001 and this pattern was consistently seen at follow-up D7 and D14. However, dry eye complaints were not correlated with the three objective dry eye measurements in mild-moderate COVID-19 patients. NO RT‒PCR results were positive in 32 (20.4%) patients, namely, 13 and 19 moderate-severe and mild COVID-19 patients, respectively. Positive RT‒PCR results were observed in 7/157 (4.5%) conjunctival swab samples from 1 in non-COVID-19 group and 6 in mild group.

Conclusion

In the early phase of infection, COVID-19 patients experience dry eye symptoms, which have no correlation with objective dry eye measurements. SARS-CoV-2 in conjunctival swab samples can be detected in patients with normal-to-mild COVID-19, which shows the risk of ocular transmission.

Comprehensive Profile of Pathogens and Antimicrobial Resistance in Conjunctivitis Cases from Niger

Infectious conjunctivitis outbreaks remain a public health burden. This study focuses on the pathogen and antimicrobial resistance (AMR) profiles identified in Niger. Sixty-two patients with acute infectious conjunctivitis who presented to health posts were enrolled from December 2021 to May 2022. Nasal and conjunctival swabs were obtained from each patient. Unbiased RNA deep sequencing (RNA-seq) was used to identify associated pathogens. A pathogen was identified in 39 patients (63%; 95% CI, 50-74). Of those, an RNA virus was detected in 23 patients (59%; 95% CI, 43-73). RNA viruses were diverse and included human coronaviruses (HCoVs): SARS-CoV-2, HCoV-229E, HCoV-HKU1, and HCoV-OC43. A DNA virus was identified in 11 patients (28%; 95% CI, 17-44). Of those, four patients had a coinfection with an RNA virus and two patients had a coinfection with both an RNA virus and a bacterium. DNA viruses were predominantly human herpesvirus (cytomegalovirus, Epstein-Barr virus, human herpesvirus 8) and human adenovirus species B, C, and F. Eighteen patients (46%; 95% CI, 32-61) had a bacteria-associated infection that included Haemophilus influenza, Haemophilus aegyptius, Staphylococcus aureus, Streptococcus pneumoniae, and Moraxella spp. Antimicrobial resistance determinants were detected in either the conjunctiva or nasal samples of 20 patients (32%; 95% CI, 22-45) and were found to be more diverse in the nose (Shannon alpha diversity, 1.12 [95% CI, 1.05-1.26] versus 1.02 [95% CI, 1.00-1.05], P = 0.01). These results suggest the potential utility of leveraging RNA-seq to surveil pathogens and AMR for ocular infections.

Personalized 3D Printed Eye Gear for Microscopic Surgeons Amidst and beyond COVID-19

The COVID-19 pandemic underscored the need for enhanced protective measures for healthcare workers, particularly surgeons, who face a heightened risk of exposure to infectious aerosols. However, conventional eye protection equipment such as face shields, goggles, or glasses often leads to ergonomic discomfort and a reduced field of view (FOV), impeding surgeons' ability to perform microsurgical procedures with precision and ease. To address these limitations, this study aimed to develop personalized 3D-printed eye gear for microscopic surgeons based on facial anthropometry data. 3D scanning was employed to obtain facial data from ten neurosurgery residents. Utilizing computer-aided designing, eye gears tailored to the unique facial features of each participant were developed. Finite element analysis-based contact simulation was used to assess the pressure exerted by the eye gear. Multi-material 3D printing was employed to fabricate the personalized eye gear. Participants, while donning the eye gear, engaged in simulation-based micro suturing tasks at various magnifications of the operating microscope, and marked the FOV range. They provided feedback scores (1-10) on the effectiveness of the eye gear through a Likert scale questionnaire (Q1-Q8). Finite element analysis demonstrated uniform strain distribution on the face, indicating that the edges of the customized eye gear fit exactly to the user's face. The average scores for the questionnaire Q1 to Q8 ranged from 6.8 to 8.5, with an overall mean score of 7.6. This indicates that the developed eye gear was simple to use and did not cause any discomfort. Additionally, the average reduction in the FOV was only 10.93% across the different operating microscope magnifications. These findings highlight eye gear's potential to alleviate discomfort and enhance precision in microscopic surgeries. Consequently, personalized 3D-printed eye gear offers a promising solution for providing surgeons with a safe environment while preserving the benefits of the operating microscope.

Ocular manifestations of COVID-19: systematic review and meta-analysis

OBJECTIVE

Our study aims to build on our understanding of COVID-19 by detailing a comprehensive look at the prevalence of different ocular manifestations related to COVID-19 infection.

DESIGN

Systematic review and meta-analysis.

METHODS

Eligible studies published between June 20, 2021, and May 11, 2023, were retrieved from the MEDLINE, EMBASE, and CINAHL databases as well as grey literature. Covidence was used to conduct the systematic review. Duplicate records were removed, and 2 independent reviewers screened records for relevance. After screening, a risk-of-bias assessment was carried out. Data were extracted, and a meta-analysis was performed using STATA 14.0. Fixed-effects and random-effects models were computed based on heterogeneity.

RESULTS

Our meta-analysis included 43 articles with a total of 10,572 subjects. The results showed that COVID-19 patients had a significantly higher prevalence of conjunctivitis (effect size [ES] = 0.11; 95% CI, 0.07-0.15), ptosis (ES = 0.22; 95% CI, 0.15-0.30), and ophthalmoplegia (ES = 0.40; 95% CI, 0.06-0.74). Our results also indicate that COVID-19 patients have higher prevalence of cotton wool spots (ES = 0.06; 95% CI, 0.03-0.09), retinal hemorrhages (ES = 0.12; 95% CI, 0.06-0.18), and retinal vein tortuosity (ES = 0.19; 95% CI, 0.09-0.35).

CONCLUSION

COVID-19 can exhibit extrapulmonary manifestations, affecting both the anterior and posterior segments of the eye. Common anterior-segment findings include conjunctivitis, whereas posterior-segment findings may include cotton wool spots, retinal hemorrhages, and retinal vein tortuosity. Improving our understanding of the ocular manifestations of COVID-19 has the potential to facilitate quicker diagnosis and subsequent treatment.

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.

Incidence and clinical characteristic of ocular surface manifestation: an evaluation of conjunctival swab results in Corona Virus 2019 (COVID-19) patients in Jakarta, Indonesia

OBJECTIVES

This study aimed to investigate the spectrum of ocular characteristics and viral presence in the conjunctival swab of patients with COVID-19.

METHODS

In this cross-sectional study, fifty-three patients were recruited from two COVID-19 referral hospitals in Jakarta (Cipto Mangunkusumo Hospital and Persahabatan Hospital) from July 2020 to March 2021. The inclusion criteria were patients who were suspected of or confirmed cases of COVID-19 with or without ocular symptoms. Demographic data, history of COVID-19 exposure, underlying medical condition, systemic symptoms, ocular symptoms, supporting laboratory results, reverse-transcriptase polymerase chain reaction (RT-PCR) of naso-oropharyngeal (NOP) swab and conjunctival swab were collected.

RESULTS

Fifty-three patients who were suspected, probable or confirmed cases of Covid-19 were included. Forty-six out of 53 patients (86.79%) tested positive for either Covid-19 antibody rapid test or naso-oropharyngeal (NOP) swab. Forty-two patients tested positive for NOP swab. Fourteen out of 42 patients (33.33%) experienced symptoms of ocular infection including red eye, epiphora, itchy eyes, and eye discharge. None of these patients were tested positive for conjunctival swab. Two out of 42 patients (4.76%), who were tested positive for conjunctival swab, did not experience any ocular symptoms.

CONCLUSIONS

Establishing the relationship between Covid-19 infection, ocular symptoms, and presence of SARS-CoV-2 virus on the ocular surface proves to be challenging. In Covid-19 patients, ocular symptoms did not warrant a positive conjunctival swab result. On the contrary, a patient without ocular symptoms can also have detectable presence of SARS-CoV-2 virus on the ocular surface.

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.

Effect of Covid-19 on Eye Banks and Corneal Transplantations: Current Perspectives

The coronavirus disease 2019 (COVID-19) pandemic exerted a great impact on medical practice, which was reframed according to the actual needs. Ophthalmological services and procedures including corneal transplantation did not represent an exception. The adoption and implementation of new standard operating procedures as well as of new technologies for remote consultation and smart-working reshaped daily activities of both eye bankers, physicians, researchers, and patients. Regulatory restrictions were issued redefining corneal donor eligibility criteria, as well as handling and harvesting procedures of donor ocular tissues. Surgical schedules underwent an abrupt contraction with prioritization of urgent procedures. Local lockdowns and confinement strategies resulted in both a reduction and redirection of research activities. The evaluation of SARS-CoV-2 colonization of ocular tissues, long-term corneal storage techniques, new disinfection strategies, split corneal transplants and cell-based therapies for the treatment of corneal disease peaked in the pipeline. Aim of this article is to summarizes the overall impact of the pandemic on the corneal transplantation machinery, and the current and future perspectives for the corneal transplant community.

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.

Analysis of macular structure in age-related cataract patients with different antibody levels of severe acute respiratory syndrome coronavirus-2 vaccine

Objective

To analyze the macular structure of age-related cataract (ARC) patients with different antibody levels after COVID-19 vaccine injection, in order to obtain the effect of COVID-19 vaccine on the macular structure, and speculate whether the COVID-19 vaccine has adverse effects on the macular structure.

Methods

This retrospective study is conducted to analysis on the status of COVID-19 vaccine and the thickness of different layers at different positions in the macular area of ARC patients. In the age, sex and eye axial length matched population, in the un-injection, no-antibody, IgM and IgG positive groups after vaccination, the choroid, ganglion cell complex, nerve fiber layer and retinal thickness at different positions of ETDRS zoning in the macular area were discussed.

Results

A total of 164 patients (164 eyes) were included in the analysis. There were 63 males and 101 females. The average age was 65.99 ± 8.43 years. There was no significant difference in age and sex among the groups (p>0.05). The average axial length of 164 eyes was 23.56 ± 1.46mm, and no significant difference between the groups (p>0.05). Non parametric test and ANOVA test for the thickness of choroid, retina, ganglion cell complex and retinal nerve fiber layer in each division of ETDRS showed no significant difference in the four groups of un-injection, no-antibody, IgM and IgG (p>0.05). There was no correlation between the antibody concentration and the thickness of macular structure (p>0.05).

Conclusion

There was no significant difference in the thickness of choroid, retina, ganglion cell complex and retinal fiber layer in different macular areas after COVID-19 vaccine injection. There was no linear correlation between the thickness of choroid, retina, ganglion cell complex and retinal fiber layer and the antibody concentration produced after COVID-19 vaccine injection. It suggests that the injection of COVID-19 vaccine might have no significant effect on the macular structure of eye.

Is orbital wall fracture associated with SARS-CoV-2 ocular surface contamination in asymptomatic COVID-19 patients?

Objectives

To assess the relationship between orbital wall fractures connecting to  paranasal sinuses (OWF-PNS) and SARS-CoV-2 ocular surface contamination (SARS-CoV-2-OSC) in asymptomatic COVID-19 patients.

Methods

This was a prospective case–control study enrolling two asymptomatic COVID-19 patient cohorts with vs. without OWF-PNS in the case–control ratio of 1:4. All subjects were treated in a German level 1 trauma center during a one-year interval. The main predictor variable was the presence of OWF-PNS (case/control); cases with preoperative conjunctival positivity of SARS-CoV-2 were excluded to rule out the possibility of viral dissemination via the lacrimal gland and/or the nasolacrimal system. The main outcome variable was laboratory-confirmed SARS-CoV-2-OSC (yes/no). Descriptive and bivariate statistics were computed with a statistically significant P ≤ 0.05.

Results

The samples comprised 11 cases and 44 controls (overall: 27.3% females; mean age, 52.7 ± 20.3 years [range, 19–85]). There was a significant association between OWF-PNS and SARS-CoV-2-OSC (P = 0.0001; odds ratio = 20.8; 95% confidence interval = 4.11–105.2; R-squared = 0.38; accuracy = 85.5%), regardless of orbital fracture location (orbital floor vs. medial wall versus both; P = 1.0).

Conclusions

Asymptomatic COVID-19 patients with OWF-PNS are associated with a considerable and almost 21-fold increase in the risk of SARS-CoV-2-OSC, in comparison with those without facial fracture. This could suggest that OWF-PNS is the viral source, requiring particular attention during manipulation of ocular/orbital tissue to prevent viral transmission.

The Effect of COVID-19 on Corneal Donor Volumes and Eye Bank Processes: An Analysis From the Eye Bank of Canada (Ontario Division)

PURPOSE

With the rise in COVID-19 cases, the Eye Bank of Canada (Ontario Division), the largest eye bank in Canada, was faced with challenges related to ocular donor suitability which resulted in tissue shortages after the first wave of COVID-19 cases in Ontario, Canada. This article aims to analyze the impact of COVID-19 on ocular tissue donation and transplant surgeries.

METHODS

Trends in ocular donations in 2020 and the transplant rates were compared with the data from the previous year, as a benchmark of normal eye bank activity.

RESULTS

Ocular donor volumes decreased during the first wave of the COVID-19 pandemic (March-June 2020) by 65% as compared to the same period in 2019. By the end of the year 2020, this had resulted in a total reduction of 29% of ocular donor volumes as compared to 2019. The ocular transplant surgery volumes in the year 2020 decreased by 32% compared to the previous year, mostly secondary to elective surgery shutdown during the first wave. Because of tissue shortages, the Eye Bank of Canada (Ontario Division) had to import 24 corneas from the United States and cancel 7 surgeries in the year 2020.

CONCLUSIONS

The decline in ocular tissue donor volumes and transplant surgery was a result of an interplay of causes related to the COVID-19 pandemic. Most importantly, ruling out of COVID-19 carriers, lockdown measures affecting tissue retrieval processes, and shutdown of elective surgery were the 3 major factors accounting for tissue shortages and surgical volume reductions.

Prevalence of SARS-CoV-2 in Conjunctival Swab Samples Among Patients Presenting with Conjunctivitis During the COVID-19 Pandemic

Purpose

To investigate the prevalence of SARS-CoV-2-associated conjunctivitis among patients presenting with conjunctivitis to ophthalmology clinics in the absence of respiratory symptoms suggesting COVID-19 during the first year of the pandemic.

Patients and Methods

This prospective, observational, cross-sectional study enrolled patients aged 18 years and older who presented with acute conjunctivitis between May 2020 and May 2021. After reviewing demographics, ocular and systemic symptoms, a slit lamp examination was performed. Five samples were collected (conjunctival swab from each eye, nasal swab from each nostril, and a nasopharyngeal swab) in separate tubes for a reverse transcription-polymerase chain reaction test for SARS-CoV-2. Patients were called at 1 and 2 weeks to follow up on their ocular and systemic symptoms and collect information about conjunctival adenovirus test results and COVID-19 test results if performed outside of the study.

Results

A total of 36 patients were enrolled. The most common ocular symptom was redness (35/36, 97%), and 14 patients (39%) had symptoms in both eyes at the time of the presentation. SARS-CoV-2 RNA was not detected in any samples collected during the study visit (95% confidence interval [CI] from 0 to 0.08). None of the study participants were diagnosed with COVID-19 following conjunctivitis during the 2-week follow-up period. We found that 25 patients had a conjunctival adenovirus test done on the day of their study visit, 9 of which reported positive results.

Conclusion

Our data suggest that it may not be valuable to obtain routine testing of SARS-CoV-2 in patients presenting with conjunctivitis in the absence of COVID-19.

Detection of SARS-CoV-2 RNA in Urine by RT-LAMP: A Very Rare Finding

Detection of SARS-CoV-2 is routinely performed in naso/oropharyngeal swabs samples from patients via RT-qPCR. The RT-LAMP technology has also been used for viral RNA detection in respiratory specimens with both high sensitivity and specificity. Recently, we developed a novel RT-LAMP test for SARS-CoV-2 RNA detection in nasopharyngeal swab specimens (named, N15-RT-LAMP) that can be performed as a single-tube colorimetric method, in a real-time platform, and as dry-LAMP. To date, there has been very little success in detecting SARS-CoV-2 RNA in urine by RT-qPCR, and the information regarding urine viral excretion is still scarce and not comprehensive. Here, we tested our N15-RT-LAMP on the urine of 300 patients admitted to the Hospital of Salamanca, Spain with clinical suspicion of COVID-19, who had a nasopharyngeal swab RT-qPCR-positive (n = 100), negative (n = 100), and positive with disease recovery (n = 100) result. The positive group was also tested by RT-qPCR for comparison to N15-RT-LAMP. Only a 4% positivity rate was found in the positive group via colorimetric N15-RT-LAMP and 2% via RT-qPCR. Our results are consistent with those obtained in other studies that the presence of SARS-CoV-2 RNA in urine is a very rare finding. The absence of SARS-CoV-2 RNA in urine in the recovered patients might suggest that the urinary route is very rarely used for viral particle clearance.

Identification of tear-based protein and non-protein biomarkers: Its application in diagnosis of human diseases using biosensors

Discovery of robust, selective and specific biomarkers are important for early diagnosis and monitor progression of human diseases. Eye being a common target for several human diseases, vision impediment and complications are often associated with systemic and ocular diseases. Tears are bodily fluids that are closest to eye and are rich in protein content and other metabolites. As a biomarker repository, it advantages over other bodily fluids due to the ability to collect it non-invasively. In this review, we highlight some recent advancements in identification of tear-based protein biomarkers like lacryglobin and cystatin SA for cancer; interleukin-6 and immunoglobulin-A antibody for COVID-19; tau, amyloid-β-42 and lysozyme-C for Alzheimer's disease; peroxiredoxin-6 and α-synuclein for Parkinson's disease; kallikrein, angiotensin converting enzyme and lipocalin-1 for glaucoma; lactotransferrin and lipophilin-A for diabetic retinopathy and zinc-alpha-2 glycoprotein-1, prolactin and calcium binding protein-A4 for eye thyroid disease. We also discussed identification of tear based non-protein biomarkers like lysophospholipids and acetylcarnitine for glaucoma, 8-hydroxy-2'-deoxyquanosine and malondialdehyde for thyroid eye disease. We elucidate technological advancement in developing tear-based biosensors for diagnosis and monitoring diseases such as diabetes, diabetic retinopathy and Alzheimer's disease. Altogether, the study of tears as potential biomarkers for early diagnosis of human diseases is promising.

Assessment of temporal and spatial distribution patterns of aerosol produced by air-puff non-contact tonometer

PURPOSE

To assess the distribution pattern of aerosol in the aspect of time and direction during the intraocular pressure (IOP) measurement by air-puff non-contact tonometer (NCT) and further offer references for protection from coronavirus disease-19 (COVID-19) in the routine ophthalmic examination.

METHOD

A single-center observational study was conducted in the ophthalmology clinics of Peking University Third Hospital. Two air quality detectors were equipped to assess the generated particulate matter (PM) concentration simultaneously within 30 s after IOP measurement in the outpatient hall. Detector A was fixed next to the NCT as a reference, while Detector B was fixed 1 meter away. The participants were divided into two groups depending on the position of Detector B. The generation of aerosol was compared within different groups and time intervals.

RESULTS

144 participants were enrolled in the final analysis. At a 1 m distance from the NCT, the PM_2.5 concentration significantly increased at the 30 s (Z = 2.898, Bonferroni-corrected P = 0.038) while the PM₁₀ concentration increased immediately after the IOP measurement (Z = 2.967, Bonferroni-corrected P = 0.030). The PM_2.5 and PM₁₀ concentrations at 1 m were significantly higher immediately (Z = -2.183, P = 0.029; Z = -2.502, P = 0.012) and 30 s (Z = -2.021, P = 0.043; Z = -2.071, P = 0.038) after the IOP measurements when the Detector B was vertical to the air jet on the lateral side.

CONCLUSIONS

NCT may produce aerosol after the IOP measurement by air-puff. The generated PM_2.5 had a prolonged existence compared with PM₁₀ at a 1 m distance. The lateral side of the air-puff direction may be of higher exposure risk to aerosol.

Detection of COVID-19 in tears of ICU-admitted patients with SARS-CoV-2 infection

Purpose

Upon the outbreak of 2019, novel coronavirus (COVID-19) pandemic confirmed the cases surpassed 20 million. Despite a few reports identified the association of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with ocular manifestations, it may assess the ocular symptoms of patients with the COVID-19 by ophthalmologists facilitate the diagnosis and prevent transmission.

Methods

A total of 60 patients with the COVID-19 admitted to Baghiatallah hospital from March 2020 to May 2020 were retrospectively reviewed and analyzed for the ocular manifestations, blood tests, and reverse transcriptase-polymerase chain reaction (RT-PCR) for SARS-CoV-2 using nasopharyngeal and conjunctival swabs.

Results

Among 60 included patients with clinically confirmed COVID-19, the median age 58.36 years (IQR: 30–88 years), 27 (45%) were male. Furthermore, 29 (48%) and 5 (8%) patients yielded positive for SARS-CoV-2 on RT-PCR from nasopharyngeal swabs and conjunctival specimens, respectively. Among 60 patients, 10 (16%) and 3 (5%), respectively, had the ocular manifestations and positive results for SARS-CoV-2 on RT-PCR from conjunctival and nasopharyngeal swabs.

Conclusion

Although the positive rate of tear RT-PCR rate is not noticeable as nasopharyngeal swabs yet, COVID-19 transmission through the eyes is biologically plausible.

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

This study investigates the presence of SARS-CoV-2 in conjunctival secretions and tears and evaluates ocular symptoms in a group of patients with COVID-19. We included 56 hospitalized patients with COVID-19 in this cross-sectional cohort study. Conjunctival secretions and tears were collected using flocked swabs and Schirmer strips for SARS-CoV-2 reverse-transcriptase polymerase chain reaction (RT-PCR). Assessment of ocular surface manifestations included an OSDI (Ocular Surface Disease Index) questionnaire. Patients had been admitted to hospital for an average of 2.4 days (range 0–7) and had shown general symptoms for an average of 7.1 days (range 1–20) prior to ocular testing. Four (7.1%) of 56 conjunctival swabs and four (4%) of 112 Schirmer strips were positive for SARS-CoV-2. The mean E-gene cycle threshold values (Ct values) were 31.2 (SD 5.0) in conjunctival swabs and 32.9 (SD 2.7) in left eye Schirmer strips. Overall, 17 (30%) patients presented ocular symptoms. No association was found between positive ocular samples and ocular symptoms. This study shows that SARS-CoV-2 can be detected on the conjunctiva and tears of patients with COVID-19. Contact with the ocular surface may transmit the virus and preventive measures should be taken in this direction.

Instability of Tear Film after Novel Coronavirus Disease: A Noninvasive and No Contact Method by a Scheimpflug-Placido Disc Topographer

PURPOSE

To compare the topographical tear film break-up time (T-BUT) between individuals recovering from COVID-19 and control subjects using a noninvasive and noncontact technique with a Scheimpflug-Placido disc topographer.

METHODS

One-hundred and twenty-two eyes from 61 post-COVID-19 patients and 124 eyes from 62 control subjects were included in this prospective study. All participants underwent detailed ophthalmological examination including best-corrected visual acuity, intraocular pressure measurements, slit lamp examination, and fundoscopy as well as qualitative and quantitative evaluation of the noninvasive first tear film break-up time (NIF-BUT) and noninvasive average tear film break-up time (NIAvg-BUT) with T-BUT measured with a Sirius (CSO - Costruzione Strumenti Oftalmici S. r. l., Italy) corneal topography device.

RESULTS

The mean NIF-BUT in post-COVID-19 and control patients was 5.2 ± 3.4 vs. 6.5 ± 3.2 sec, respectively. The mean NIAvg-BUT in the corresponding groups was 7.5 ± 3.5 vs. 8.8 ± 3.0 sec, respectively. Both NIF-BUT and NIAvg-BUT were significantly lower in the post-COVID-19 group than in controls (p = 0.004 vs. 0.020). Topographical tear film break-up at any time during the test (17 sec) was observed qualitatively in 79 eyes (64.8%) in the post-COVID-19 group and 57 eyes (46%) in the control group (p = 0.003). Moreover, temporal quadrant involvement occurred significantly more frequently in the post-COVID-19 group (p = 0.028).

CONCLUSION

Tear film stability assessment based on T-BUT showed shorter NIF-BUT and NIAvg-BUT in post-COVID-19 patients as compared to the control group. Our results suggest that post-COVID-19 patients have impaired stability of tear film, and therefore require closer monitoring regarding dry eye. In addition, tear film instability in post-COVID-19 patients can be reliably detected using a noninvasive and noncontact technique that is more comfortable for both patients and physicians.

Clinical Profile of COVID-19 Patients Presenting with Uveitis - A Short Case Series

Purpose

To present the clinical features of anterior, intermediate and posterior uveitis in patients with COVID-19 and to increase the awareness of the treating physicians to refer patients with COVID-19 who have eye symptoms for ophthalmic exam, in order to diagnose as early as possible and prevent vision-threatening complications.

Methods

Retrospective observational case reports.

Results

We report three cases of COVID-19 patients who developed uveitis during or after the course of their sickness with COVID-19. All patients underwent a detailed eye examination, relevant history and investigations did not prove any other cause of uveitis.

Conclusion

This report presents novel data on the course of subjects with uveitis during the COVID-19 pandemic. Intermediate and posterior uveitis warrant further evaluation with differential diagnosis supported by laboratory tests due to the association with systemic diseases and risk of permanent vision loss. Iridocyclitis, intermediate, and posterior uveitis treatment should be guided by ophthalmologists, particularly uveitis specialists, when possible.

Manifestations and Virus Detection in the Ocular Surface of Adult COVID-19 Patients: A Meta-Analysis

Purpose

This study aims to examine the prevalence rate of ocular manifestations and the positive rate for the real-time reverse transcriptase-polymerase chain reaction (RT-PCR) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in conjunctival/tear swabs among adult patients with coronavirus disease 2019 (COVID-19).

Methods

PubMed and EMBASE were reviewed between December 1, 2019, and January 31, 2021, and only peer-reviewed clinical studies in our pooled analyses were included. Details regarding the patient numbers, demographics, ocular manifestations, positivity of ocular surface RT-PCR, and severity of pneumonia were recorded from each study. Primary outcomes were the occurrence of ocular manifestations and virus detection on the ocular surface. Meanwhile, secondary outcomes included frequencies of various ocular symptoms/signs (s/s), the proportion of patients with ocular manifestation as the initial symptom, and the relationship between the severity of pneumonia and the presentation of ocular manifestations.

Results

In total, 35 studies with 4,432 adult COVID-19 patients were included in this analysis. The overall prevalence rate of ocular manifestations was found to be 11.3%, and the positive rate of SARS-CoV-2 in the ocular surface was 7.4%. The four most common ocular s/s were follicular conjunctivitis, redness, watering, and discharge. A proportion of 3.3% presented with ocular s/s preceding other findings. Besides, patients with higher severity of pneumonia were more likely to have ocular manifestations (odds ratio = 2.25; 95% confidence interval (CI): 1.45-3.50).

Conclusion

As per our findings, it was determined that ocular transmission of SARS-CoV-2 might be possible, highlighting the importance of eye protective equipment among healthcare personnel.

Ocular Involvement in COVID-19: Conjunctivitis and More

Since the beginning of 2020, SARS-CoV-2, the pathogen of COVID-19, has led to a global pandemic that also affects ophthalmology. Ophthalmologists can be confronted at any time with potentially COVID-19 associated ocular symptoms or manifestations in patients and also become infected through close patient contact. Even without systemic infection, the ocular surface can come into direct contact with aerosols or liquids containing SARS-CoV-2 particles. A smear infection through hand-to-eye contact is also possible. A purely isolated ocular infection has not yet been shown. Rather, it seems that ocular complications occur in the context of a systemic infection. However, ocular symptoms can also be the first symptom of COVID-19. The most common ocular complication of COVID-19 is mild follicular conjunctivitis. Haemorrhagic conjunctivitis, dry eye disease, episcleritis, or retinal involvement can also occur less frequently. There are currently no evidence-based therapy recommendations for COVID-19 associated diseases of the ocular surface. Artificial tears might be helpful for symptom relief. There is no evidence for antiviral, antibiotic, or anti-inflammatory therapies, but these medications might be used in individual cases. Potential intraocular complications include retinal artery occlusions and haemorrhages, as well as cotton wool spots caused by complement-mediated thrombotic angiopathy. Neuro-ophthalmological complications including Miller-Fisher syndrome or infarct-related central blindness can also occur in very rare cases. Knowledge of potential transmission routes and personal protective equipment is just as essential for each ophthalmologist as a basic knowledge of potential ocular symptoms and complications.

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.

Diagnosis of SARS-Cov-2 Infection by RT-PCR Using Specimens Other Than Naso- and Oropharyngeal Swabs: A Systematic Review and Meta-Analysis

The rapid and accurate testing of SARS-CoV-2 infection is still crucial to mitigate, and eventually halt, the spread of this disease. Currently, nasopharyngeal swab (NPS) and oropharyngeal swab (OPS) are the recommended standard sampling techniques, yet, these have some limitations such as the complexity of collection. Hence, several other types of specimens that are easier to obtain are being tested as alternatives to nasal/throat swabs in nucleic acid assays for SARS-CoV-2 detection. This study aims to critically appraise and compare the clinical performance of RT-PCR tests using oral saliva, deep-throat saliva/posterior oropharyngeal saliva (DTS/POS), sputum, urine, feces, and tears/conjunctival swab (CS) against standard specimens (NPS, OPS, or a combination of both). In this systematic review and meta-analysis, five databases (PubMed, Scopus, Web of Science, ClinicalTrial.gov and NIPH Clinical Trial) were searched up to the 30th of December, 2020. Case-control and cohort studies on the detection of SARS-CoV-2 were included. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS 2). We identified 1560 entries, 33 of which (1.1%) met all required criteria and were included for the quantitative data analysis. Saliva presented the higher accuracy, 92.1% (95% CI: 70.0-98.3), with an estimated sensitivity of 83.9% (95% CI: 77.4-88.8) and specificity of 96.4% (95% CI: 89.5-98.8). DTS/POS samples had an overall accuracy of 79.7% (95% CI: 43.3-95.3), with an estimated sensitivity of 90.1% (95% CI: 83.3-96.9) and specificity of 63.1% (95% CI: 36.8-89.3). The remaining index specimens could not be adequately assessed given the lack of studies available. Our meta-analysis shows that saliva samples from the oral region provide a high sensitivity and specificity; therefore, these appear to be the best candidates for alternative specimens to NPS/OPS in SARS-CoV-2 detection, with suitable protocols for swab-free sample collection to be determined and validated in the future. The distinction between oral and extra-oral salivary samples will be crucial, since DTS/POS samples may induce a higher rate of false positives. Urine, feces, tears/CS and sputum seem unreliable for diagnosis. Saliva testing may increase testing capacity, ultimately promoting the implementation of truly deployable COVID-19 tests, which could either work at the point-of-care (e.g. hospitals, clinics) or at outbreak control spots (e.g., schools, airports, and nursing homes).

Evidence of SARS-CoV-2 Transmission Through the Ocular Route

PURPOSE

Currently, the coronavirus disease 2019 (COVID-19) pandemic is raging around the world. However, the transmission of its pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is not fully clear. It is still controversial whether the ocular transmission of SARS-CoV-2 exists. This review aimed to summarize the evidence of SARS-CoV-2 ocular transmission.

METHODS

Online articles were searched till October 23, 2020 in Pubmed, Embase, and websites of World Health Organization, Centers for Disease Control and Prevention COVID-19, American Academy of Ophthalmology, and American Society of Cataract and Refractive Surgery under the search strategy of (((("COVID-19"[Mesh]) OR ("SARS-CoV-2"[Mesh])) OR (2019 novel coronavirus)) OR (2019-nCoV)) AND (((("Conjunctivitis"[Mesh]) OR (Ocular Surface)) OR ("Eye"[Mesh])) OR ("Ophthalmology"[Mesh])). The language was not restricted. After screening, 1445 records were excluded and 168 references original articles were finally included.

RESULTS

Cells of ocular surface express both the receptor of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), offering molecular bases for the ocular susceptibility to SARS-CoV-2. Accumulated COVID-19 patients presented conjunctivitis as the initial or the only symptom. Whether COVID-19 patients had ocular symptoms or not, SARS-CoV-2 was detectable on the ocular surface, and the isolated virus was infectious, proving that the ocular surface can not only be a reservoir but also a source of contagion. SARS-CoV-2 may reach the ocular surface by hand-eye contact and aerosols. Once SARS-CoV-2 reaches the ocular surface, it may transfer to other systems through the nasolacrimal system or hematogenous metastasis.

CONCLUSION

The ocular surface can serve as a reservoir and source of contagion for SARS-CoV-2. SARS-CoV-2 can be transmitted to the ocular surface through hand-eye contact and aerosols, and then transfer to other systems through nasolacrimal route and hematogenous metastasis. The possibility of ocular transmission of SARS-CoV-2 cannot be ignored.

Detection of coronavirus-2 by real-time reverse transcription polymerase chain reaction in conjunctival swabs from patients with severe form of Coronavirus disease 2019 in São Paulo, Brazil

OBJECTIVES

To test conjunctival swabs from patients with laboratory-confirmed severe forms of coronavirus disease 2019 (COVID-19) for the presence of SARS-CoV-2 on real-time reverse-transcription polymerase chain reaction (rRT-PCR).

METHODS

Fifty conjunctival swabs were collected from 50 in-patients with laboratory-confirmed severe forms of COVID-19 at the largest teaching hospital and referral center in Brazil (HCFMUSP, São Paulo, SP). The samples were tested for SARS-CoV-2 on rRT-PCR with the primers and probes described in the CDC protocol which amplify the region of the nucleocapsid N gene (2019_nCoV_N1 and 2019_nCoV_N2) of SARS-CoV-2 RNA and compared with naso/oropharyngeal swabs collected within 24 hours of the conjunctival swabs.

RESULTS

Five conjunctival samples (10%) tested positive (amplification of the N1 and N2 primer/probe sets) while two conjunctival samples (4%) yielded inconclusive results (amplification of the N1 primer/probe set only). The naso/oropharyngeal swabs were positive for SARS-CoV-2 on rRT-PCR in 34 patients (68%), negative in 14 (28%) and inconclusive in 2 (4%). The 5 patients with positive conjunctival swabs had positive (n=2), negative (n=2) or inconclusive (n=1) naso/oropharyngeal swabs on rRT-PCR. Patients with negative or inconclusive naso/oropharyngeal swabs had the diagnosis of COVID-19 confirmed by previous positive rRT-PCR results or by serology.

CONCLUSION

This is the first study to present conjunctival swab rRT-PCR results for SARS-CoV-2 in a Brazilian population. In our sample of 50 patients with severe forms of COVID-19, 10% had positive conjunctival swabs, most of which were correlated with positive naso/oropharyngeal rRT-PCR results.

Detection of SARS-CoV-2 in the ocular surface in different phases of COVID-19 patients in Shanghai, China

Background

To investigate the temporal pattern of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presence on ocular surfaces using conjunctival swabs in coronavirus disease 2019 (COVID-19) patients.

Methods

This study included 59 patients (32 newly admitted and 27 hospitalized for ≥2 weeks) with a COVID-19-confirmed diagnosis at the Shanghai Public Health Clinical Center from March 3, 2020, to March 21, 2020. Conjunctival swab samples were collected from both eyes of all the 59 patients and were tested by reverse transcription polymerase chain reaction (RT-PCR) assay. The range of sampling time lies widely between 1 and 50 days since symptom onset.

Results

Among the 32 newly admitted patients, positive RT-PCR results for SARS-CoV-2 in conjunctival swab samples were reported in 2 patients (one eye for each) without ocular discomfort, but 1 positive case had conjunctival congestion. The positive results were detected on Day 5 for 1 patient and Day 7 for the other, but repeated tests after 1 week were negative for both patients. All 27 patients who had been hospitalized for ≥2 weeks had negative test results. The mean time from symptom onset to sampling of 2 positive cases was significantly less than that of 57 negative cases (P<0.001).

Conclusions

SARS-CoV-2 on the ocular surface can be detected in the early phase of COVID-19. The risk of ocular transmission remains and might be higher in the early phase.