ACE2 and TMPRSS2 are expressed on the human ocular surface, suggesting susceptibility to SARS-CoV-2 infection

Clinical characteristics and viral colonization of corneal donors with coronavirus disease 2019: a comprehensive analysis before and after corneal transplantation

PURPOSE

To evaluate the clinical characteristics and viral Colonization of corneas donated by volunteers with coronavirus disease 2019 (COVID-19) before and after corneal transplantation.

METHODS

We retrospectively compared the characteristics and clinical outcomes of patients who received corneas from donors with and without a history of COVID-19 after corneal transplantation. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to evaluate the expression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA on ocular surfaces in corneal preservation solutions as well as the recipients' tears. Immunofluorescence was also performed to evaluate the expression of viral spike proteins in the corneas. Intraocular pressure (IOP) measurement, optical coherence tomography (OCT), and slit-lamp inspection at each follow-up examination were performed to assess the surgical efficacy.

RESULTS

The RT-PCR results of eye surface swabs before corneal extraction, the corneal preservation solutions before transplantation as well as the recipients' tears were negative, thereby indicating the suitability for transplantation. No significant differences in IOP measurements, OCT findings, or in the incidence of post transplantation complications were observed between donors with and without COVID-19.

CONCLUSIONS

Corneal transplantation using corneas from COVID-19 infected donors does not alter clinical outcomes when compared to controls receiving corneas from non-infected donors.

Postmortem Ultrastructural Analysis of the Retina from COVID-19 Deceased Patients

PURPOSE

COVID-19 (coronavirus disease 2019) is an infectious disease caused by SARS-CoV-2, first reported in 2019 in Wuhan, China. Among the common complications is a pro-inflammatory and hypercoagulative response that compromises the vasculature among various organs.

METHODS

In this report, we present the postmortem retinal findings of five patients observed by means of optical microscopy and transmission and scanning electron microscopy techniques.

RESULTS

Clinical manifestations such as retinal hemorrhages and exacerbated inflammatory infiltrate, altered ultra structure with swollen mitochondria and pyknotic cells in both layers of the retina were observed in all analyzed eyes.

CONCLUSION

Our data point to the fragility of this tissue in cases of severe COVID-19.

Detection of SARS-CoV-2 binding receptors and miscellaneous targets as well as mucosal surface area of the human lacrimal drainage system

PURPOSE

Our aim was to evaluate a potential role for the lacrimal drainage system (LDS) as a portal of entry and conduit for SARS-CoV-2 in human infection. We also investigate the mucosal surface area. The relatively long tear contact time in a closed system raises the possibility that this pathway may contribute to the initiation of systemic infection. We looked for expression of ACE2, the main receptor for SARS-CoV-2, as well as cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin which also play a role in SARS-CoV-2 infection, in this system.

METHODS

Human tissue samples of the draining tear ducts from body donors were analyzed by RT-PCR, Western blot and immunohistochemistry. It is not known whether the respective body donors were Sars-Cov-2 positive at any time; they were negative when they entered the institute. Besides, the draining LDS of body donors were measured to determine the mucosal surface in the lacrimal system.

RESULTS

The expression of the main receptor studied, ACE2, cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin were all detected at the gene and protein level. The average mucosal surface area of the lacrimal sac and nasolacrimal duct was calculated to be 110 mm2.

CONCLUSION

The results show the presence of all analyzed receptors in the efferent LDS. With an average tear passage time of 3 minutes and a relatively large mucosal surface area, the LDS could therefore be considered as a portal of entry and conduit for SARS-CoV-2. In addition, it represents a surface that should be taken into consideration in the administration of topically applied medication to the ocular surface.

Natural and socio-environmental factors in the transmission of COVID-19: a comprehensive analysis of epidemiology and mechanisms

PURPOSE OF REVIEW

There are significant differences in the transmission rate and mortality rate of COVID-19 under environmental conditions such as seasons and climates. However, the impact of environmental factors on the role of the COVID-19 pandemic and the transmission mechanism of the SARS-CoV-2 is unclear. Therefore, a comprehensive understanding of the impact of environmental factors on COVID-19 can provide innovative insights for global epidemic prevention and control policies and COVID-19 related research. This review summarizes the evidence of the impact of different natural and social environmental factors on the transmission of COVID-19 through a comprehensive analysis of epidemiology and mechanism research. This will provide innovative inspiration for global epidemic prevention and control policies and provide reference for similar infectious diseases that may emerge in the future.

RECENT FINDINGS

Evidence reveals mechanisms by which natural environmental factors influence the transmission of COVID-19, including (i) virus survival and transport, (ii) immune system damage, (iii) inflammation, oxidative stress, and cell death, and (iiii) increasing risk of complications. All of these measures appear to be effective in controlling the spread or mortality of COVID-19: (1) reducing air pollution levels, (2) rational use of ozone disinfection and medical ozone therapy, (3) rational exposure to sunlight, (4) scientific ventilation and maintenance of indoor temperature and humidity, (5) control of population density, and (6) control of population movement. Our review indicates that with the continuous mutation of SARS-CoV-2, high temperature, high humidity, low air pollution levels, and low population density more likely to slow down the spread of the virus.

COVID-19 and retinal layer thickness: A bidirectional Mendelian randomization study

BACKGROUND

Observational studies have reported that COVID-19 is associated with alterations in retinal layer thickness, including changes in the ganglion cell inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL). However, the causal relationships remain unknown. Therefore, we assessed the direction and strength of the causal relationship between COVID-19 and GCIPL and RNFL thicknesses using a bidirectional two-sample Mendelian randomization (MR) design.

METHODS

Data were obtained from a large-scale COVID-19 Host Genetics Initiative (Nsample = 6,512,887), GCIPL dataset (Ncase = 31,434), and RNFL dataset (Ncase = 31,434). The inverse-variance weighted (IVW) method is the primary approach used to estimate causal effects. MR Egger, weighted median, weighted mode, MR Egger (bootstrap), and penalized weighted median methods were applied. Sensitivity analyses were implemented with RadialMR, MRPRESSO, MR-Egger regression, Cochran's Q statistic, leave-one-out analysis, and the funnel plot.

RESULTS

Forward MR analysis revealed that genetically identified COVID-19 susceptibility significantly increased the risk of GCIPL thickness (OR = 2.428, 95 % confidence interval [CI]:1.493-3.947, PIVW = 3.579 × 10-4) and RNFL thickness (OR = 1.735, 95 % CI:1.198-2.513, PIVW = 3.580 × 10-3) after Bonferroni correction. Reverse MR analysis did not indicate a significant causal association between GCIPL and RNFL thicknesses and COVID-19 phenotypes. No significant horizontal pleiotropy was found in the sensitivity analysis.

CONCLUSIONS

The host genetic liability to COVID-19 susceptibility was causally associated with increased GCIPL and RNFL thicknesses. Documenting this association increases our understanding of the pathophysiological mechanisms underlying COVID -19 susceptibility in retinopathy.

Could Ocular Glands Be Infected by SARS-CoV-2?

The aim of the study was to investigate the expression levels of ACE2 in ocular glands and to investigate the effect of S protein on them. Male C57BL/6J mice were used for the experiments. The expression levels of ACE2 are highest in the Meibomian glands, followed by the conjunctiva, the cornea, and the lacrimal glands. Co-immunoprecipitation assays confirmed direct binding between ACE2 and S protein in ocular surface epithelia and Meibomian glands. CD45+ cell infiltration was found in the S protein treatment group, which was accompanied by upregulation of inflammation-related cytokines. There was also prominent cell apoptosis in the S protein treatment group. In conclusion, not only the cornea and the conjunctiva, but also the Meibomian glands express ACE2, and S protein could induce ocular surface epithelial cell and Meibomian gland cell inflammation and apoptosis.

Ocular Implications of COVID-19 Infection and Vaccine-Related Adverse Events

The COVID-19 pandemic, caused by SARS-CoV-2, has significantly impacted various organ systems, including the eyes. Initially considered a primarily respiratory disease, it is now evident that COVID-19 can induce a range of ocular symptoms. Recognizing these ocular manifestations is crucial for eye care practitioners as they can serve as early indicators of the disease. This review consolidates current evidence on the ocular effects of COVID-19, identifying manifestations such as conjunctivitis, scleritis, uveitis, and retinopathy. The increasing prevalence of these symptoms highlights the importance of thorough eye examinations and detailed patient histories in COVID-19 cases. Potential routes of viral entry into ocular tissues and the underlying mechanisms, including direct infection, immune responses, and vascular involvement, are explored. Additionally, this review addresses ocular side effects associated with COVID-19 vaccines, such as corneal graft rejection, uveitis, and retinal issues. These findings emphasize the need for ongoing surveillance and research to ensure vaccine safety.

Molybdenum Disulfide-Assisted Spontaneous Formation of Multistacked Gold Nanoparticles for Deep Learning-Integrated Surface-Enhanced Raman Scattering

Several fabrication methods have been developed for label-free detection in various fields. However, fabricating high-density and highly ordered nanoscale architectures by using soluble processes remains a challenge. Herein, we report a biosensing platform that integrates deep learning with surface-enhanced Raman scattering (SERS), featuring large-area, close-packed three-dimensional (3D) architectures of molybdenum disulfide (MoS2)-assisted gold nanoparticles (AuNPs) for the on-site screening of coronavirus disease (COVID-19) using human tears. Some AuNPs are spontaneously synthesized without a reducing agent because the electrons induced on the semiconductor surface reduce gold ions when the Fermi level of MoS2 and the gold electrolyte reach equilibrium. With the addition of polyvinylpyrrolidone, a two-dimensional large-area MoS2 layer assisted in the formation of close-packed 3D multistacked AuNP structures, resembling electroless plating. This platform, with a convolutional neural network-based deep learning model, achieved outstanding SERS performance at subterascale levels despite the microlevel irradiation power and millisecond-level acquisition time and accurately assessed susceptibility to COVID-19. These results suggest that our platform has the potential for rapid, low-damage, and high-throughput label-free detection of exceedingly low analyte concentrations.

Dry Eye Disease: An Update on Changing Perspectives on Causes, Diagnosis, and Management

Dry eye disease is a common clinical problem encountered by ophthalmologists worldwide. Interest in this entity has increased in recent years due to the consequences it has on the ocular surface after any surface procedure. With changing times, several new factors have come to light that can influence this disease. The effect of the COVID-19 pandemic has also been greatly felt, with a range of causes, starting from increased screen work to inflammatory processes, exacerbating the condition in many. With changes in the concepts of the etiopathogenesis of the disease, a paradigm shift has taken place in the approaches to treatment. More researchers are in favor of a new tear film-oriented approach that tries to localize the disease to a single component in the tear film. Innovation of newer techniques for the treatment of meibomian gland disease has also made its foray into clinical ophthalmology. Newer drug formulations and molecules are underway to better treat the inflammatory component of the disease. Many other receptors and targets for the treatment of dry eyes are being researched. This review hopes to provide a succinct, narrative summary of the relevant research on dry eye disease to date to increase awareness about the nature and future course of this disease and its management.

Corneal Stroma Analysis and Related Ocular Manifestations in Recovered COVID-19 Patients

Purpose

The purpose of this study was to assess the impact of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) on corneal stroma characteristics, ocular manifestations, and post-recovery refractive surgery outcomes after varying recovery durations.

Methods

Fresh corneal lenticules from patients with post-coronavirus disease 2019 (COVID-19; recovered within 135 days) and healthy controls (HCs) after small incision lenticule extraction (SMILE) surgery were obtained for experimental validation of SARS-CoV-2 susceptibility, morphological changes, and immune response of the corneal stroma. Corneal optical density (CD) was measured using the Pentacam HR. Corneal epithelium thickness (ET) and endothelium parameters were evaluated by wide-field optical coherence tomography (OCT) and non-contact specular microscopy (SP-1P), respectively. All the patients were assessed after SMILE surgery until 3 month of follow-up.

Results

The cornea was susceptible to SARS-CoV-2 with the presence of SARS-CoV-2 receptors (CD147 and ACE2) and spike protein remnants (4 out of 58) in post-recovery corneal lenticules. Moreover, SARS-CoV-2 infection triggered immune responses in the corneal stroma, with elevated IL-6 levels observed between 45 and 75 days post-recovery, which were then lower at around day 105. Concurrently, corneal mid-stromal nerve length and branching were initially higher in the 60D to 75D group and returned to control levels by day 135. A similar trend was observed in CD within zones 0 to 2 and 2 to 6 and in the hexagonal cells (HEX) ratio in endothelial cells, whereas ET remained consistent. Notably, these changes did not affect the efficacy, safety, or predictability of post-recovery SMILE surgery.

Conclusions

SARS-CoV-2 induces temporal alterations in corneal stromal morphology and function post-recovery. These findings provided a theoretical basis for corneal health and refractive surgery management in the post-COVID-19 milieu.

SARS-CoV-2 infects cells lining the blood-retinal barrier and induces a hyperinflammatory immune response in the retina via systemic exposure

SARS-CoV-2 has been shown to cause wide-ranging ocular abnormalities and vision impairment in COVID-19 patients. However, there is limited understanding of SARS-CoV-2 in ocular transmission, tropism, and associated pathologies. The presence of viral RNA in corneal/conjunctival tissue and tears, along with the evidence of viral entry receptors on the ocular surface, has led to speculation that the eye may serve as a potential route of SARS-CoV-2 transmission. Here, we investigated the interaction of SARS-CoV-2 with cells lining the blood-retinal barrier (BRB) and the role of the eye in its transmission and tropism. The results from our study suggest that SARS-CoV-2 ocular exposure does not cause lung infection and moribund illness in K18-hACE2 mice despite the extended presence of viral remnants in various ocular tissues. In contrast, intranasal exposure not only resulted in SARS-CoV-2 spike (S) protein presence in different ocular tissues but also induces a hyperinflammatory immune response in the retina. Additionally, the long-term exposure to viral S-protein caused microaneurysm, retinal pigmented epithelium (RPE) mottling, retinal atrophy, and vein occlusion in mouse eyes. Notably, cells lining the BRB, the outer barrier, RPE, and the inner barrier, retinal vascular endothelium, were highly permissive to SARS-CoV-2 replication. Unexpectedly, primary human corneal epithelial cells were comparatively resistant to SARS-CoV-2 infection. The cells lining the BRB showed induced expression of viral entry receptors and increased susceptibility towards SARS-CoV-2-induced cell death. Furthermore, hyperglycemic conditions enhanced the viral entry receptor expression, infectivity, and susceptibility of SARS-CoV-2-induced cell death in the BRB cells, confirming the reported heightened pathological manifestations in comorbid populations. Collectively, our study provides the first evidence of SARS-CoV-2 ocular tropism via cells lining the BRB and that the virus can infect the retina via systemic permeation and induce retinal inflammation.

Ophthalmic Manifestations of COVID-19: A Retrospective Study on Prevalence, Characteristics, and Clinical Implications

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic, caused by the SARS-CoV-2 virus, has had far-reaching implications beyond the respiratory system. Mounting evidence suggests that COVID-19 can impact various organ systems, including the eyes. This study aimed to elucidate the prevalence, characteristics, and clinical implications of ophthalmic manifestations in patients diagnosed with COVID-19.

METHODS

This retrospective study analyzed data from electronic medical records of adult patients hospitalized with COVID-19 between March 1, 2020, and December 31, 2020, at a large tertiary academic medical center. Ophthalmic manifestations, including conjunctivitis, dry eye symptoms, ocular pain, epiphora, ocular redness, and visual disturbances, were identified and examined for their prevalence, onset, duration, and associations with COVID-19 severity and systemic symptoms.

RESULTS

Among 342 patients included in the study, 106 (31.0%) experienced at least one ophthalmic manifestation during their COVID-19 illness. Conjunctivitis was the most common manifestation in 62 patients (18.1%), followed by dry eye symptoms in 38 patients (11.1%), ocular pain/discomfort in 27 patients (7.9%), epiphora in 19 patients (5.6%), ocular redness in 14 patients (4.1%), and visual disturbances in nine patients (2.6%). Ophthalmic manifestations were significantly associated with severe COVID-19 illness (42.9% vs. 26.7%, p = 0.003) and the presence of systemic symptoms such as fever, cough, and dyspnea. The median time of onset was six days, and the median duration was 10 days.

CONCLUSIONS

Ophthalmic manifestations are prevalent in COVID-19 patients, particularly in those with severe illness and systemic symptoms. The study highlights the importance of recognizing and managing ocular symptoms in affected individuals and underscores the multifaceted nature of COVID-19, necessitating interdisciplinary collaboration for comprehensive patient care.

Expression of the SARS-CoV-2 Receptor ACE2 and Protease TMPRSS2 in Ocular Hypertension Eyes of Nonhuman Primate and Human

PURPOSE

Coronavirus disease 2019 is a disease caused by the novel severe acute respiratory syndrome coronavirus 2. The double-positive of angiotensin-converting enzyme 2 and transmembrane protease serine type 2 have a higher risk of being infected by severe acute respiratory syndrome coronavirus 2. The susceptibility of coronavirus disease 2019 in patients with chronic diseases, especially in different tissues of ocular hypertension eyes like glaucoma, is not yet known.

METHODS

An ocular hypertension model was established by laser photocoagulation in rhesus monkeys. The expression of angiotensin-converting enzyme 2 and transmembrane protease serine type 2 in three ocular hypertension eyes and the three control eyes were analyzed using immunofluorescence.

RESULTS

No difference was observed between ocular hypertension and control eyes in the expression of angiotensin-converting enzyme 2 and transmembrane protease serine type 2 in the conjunctival epithelium, corneal epithelium, and ciliary muscle. In ocular hypertension eyes and control eyes, angiotensin-converting enzyme 2 and transmembrane protease serine type 2 expression were both observed in the retina. Angiotensin-converting enzyme 2 staining of retinal ganglion cells was found to be significantly higher in ocular hypertension eyes than in control eyes. However, there was no difference in angiotensin-converting enzyme 2 and transmembrane protease serine type 2 expression in retinal vessels and choroidal vessels between ocular hypertension and control eyes. In our study, the expression and distribution of angiotensin-converting enzyme 2 and TMPREE2 in human retina were similar to that of non-human primates as expected.

CONCLUSION

Our study confirmed that angiotensin-converting enzyme 2 and transmembrane protease serine type 2 were expressed widely in rhesus monkey eyes. When compared with controls eyes, the expression of angiotensin-converting enzyme 2 was higher in the retinal ganglion cells in ocular hypertension eyes, suggesting that high ocular pressure may affect the patients' ocular susceptibility to severe acute respiratory syndrome coronavirus 2 infection.

Evaluation of the retina, choroid and optic disc vascular structures in individuals with a history of COVID-19

INTRODUCTION

In this study, we aimed to detect changes in posterior segment structures and vascular density caused by COVID-19 using an optical coherence tomography angiography (OCTA) device.

MATERIALS AND METHODS

The study included 20 eyes of 20 patients no systemic or ocular disease who were followed at the Ophthalmology Clinic of Health Sciences University Antalya Training and Research Hospital. The OCTA images of these individuals taken prior to contracting COVID-19 and six months after recovery were examined.

RESULTS

The mean choriocapillaris blood flow was 2.00±0.13mm2 before COVID-19 and 2.08±0.23mm2 after the disease, and the mean subfoveal choroidal thickness was 247.33±7.65μm before the disease and 273.08±4.92μm after the disease, indicating a statistically significant difference (P=0.003, P=0.001, respectively). The mean retinal nerve fiber layer thickness before and after COVID-19 were 119.33±3.88 and 117.50±3.92μm, respectively, representing a statistically significant decrease (P<0.001).

CONCLUSION

This is the first study in the literature to evaluate the post-COVID-19 changes in the vascular structures of the eye compared to the pre-disease values. In this study, we found statistically significant changes in choriocapillaris blood flow, subfoveal chroidal thickness and retinal nerve fiber layer thickness after COVID-19 infection. Further research with a greater sample size is needed to explore the effect of COVID-19 on these parameters.

SARS-CoV-2 mechanisms of cell tropism in various organs considering host factors

A critical step in the drug design for SARS-CoV-2 is to discover its molecular targets. This study comprehensively reviewed the molecular mechanisms of SARS-CoV-2, exploring host cell tropism and interaction targets crucial for cell entry. The findings revealed that beyond ACE2 as the primary entry receptor, alternative receptors, co-receptors, and several proteases such as TMPRSS2, Furin, Cathepsin L, and ADAM play critical roles in virus entry and subsequent pathogenesis. Additionally, SARS-CoV-2 displays tropism in various human organs due to its diverse receptors. This review delves into the intricate details of receptors, host proteases, and the involvement of each organ. Polymorphisms in the ACE2 receptor and mutations in the spike or its RBD region contribute to the emergence of variants like Alpha, Beta, Gamma, Delta, and Omicron, impacting the pathogenicity of SARS-CoV-2. The challenge posed by mutations raises questions about the effectiveness of existing vaccines and drugs, necessitating consideration for updates in their formulations. In the urgency of these critical situations, repurposed drugs such as Camostat Mesylate and Nafamostat Mesylate emerge as viable pharmaceutical options. Numerous drugs are involved in inhibiting receptors and host factors crucial for SARS-CoV-2 entry, with most discussed in this review. In conclusion, this study may provide valuable insights to inform decisions in therapeutic approaches.

COVID-19 related changes in corneal curvature and endothelium after mild infection

PURPOSE

To investigate subclinical corneal changes using corneal topography in the evaluation of corneal curvature and specular microscopy in the evaluation of the endothelial layer after mild coronavirus disease 2019 (COVID-19).

METHODS

In this prospective study, 112 eyes of 56 individuals with mild COVID-19 who recovered were investigated. Mean cell density (CD), mean coefficient of variation (CV), mean percentage of hexagonal cells, mean cell area (AVG), and central corneal thickness (CCT) were recorded from specular microscopy. K readings, including simulated keratometry flat (K1), simulated keratometry steep (K2), average keratometry (Kmean) and maximum keratometry (Kmax), pachymetric measurement and central corneal thickness (CCT), corneal volume (CV), topographic astigmatism (TA), curvature asymmetry front (CAf) and curvature asymmetry back (CAb) were recorded from corneal topography. Best corrected visual acuity (BCVA), spherical equivalant and biometric measurements were recorded.

RESULTS

The mean time interval between examinations before and after COVID-19 infection was approximately one year. Analysis of specular microscopy data showed a statistically significant change in all endothelial cell parameters (p<0.001) except the cell count (p = 0.358). The median (range) endothelial cell density (ECD) value was significantly lower after COVID-19 at 2356 (2289-2400) than before, when it was 2596 (2545-2640). Furthermore, CCT values showed a significant increase (p<0.001). The topographic values including K2, Kmax and TA and biometric measurements did not change. The Spherical Equivalant (SE) values showed significant myopic progression after COVID-19 (p<0.001).

CONCLUSION

Endothelial parameters changed more than the changes in corneal curvature and ocular biometric measurements after mild COVID-19. The decrease in endothelial cell number and hexagonality and increase in polymorphism after COVID-19 were striking.

Ocular manifestations of COVID-19: A systematic review of current evidence

Introduction

COVID-19 caused by SARS-CoV-2, commonly presents with symptoms such as fever and shortness of breath but can also affect other organs. There is growing evidence pointing to potential eye complications. In this article, we aim to systematically review the ocular manifestations of COVID-19.

Methods

We conducted a systematic review to explore the ocular manifestations of COVID-19. We searched online databases including PubMed, Embase, Scopus, and Web of Science up to September 4, 2023. After a two-stage screening process and applying inclusion/exclusion criteria, eligible articles were advanced to the data extraction phase. The PRISMA checklist and Newcastle-Ottawa Scale (NOS) were used for quality and bias risk assessments.

Results

We selected and extracted data from 42 articles. Most of the studies were cross-sectional (n = 33), with the highest number conducted in Turkey (n = 10). The most frequent ocular manifestation was conjunctivitis, reported in 24 articles, followed by photophobia, burning, chemosis, itching, and ocular pain. Most studies reported complete recovery from these manifestations; however, one study mentioned visual loss in two patients.

Conclusion

In general, ocular manifestations of COVID-19 appear to resolve either spontaneously or with supportive treatments. For more severe cases, both medical treatment and surgery have been employed, with the outcomes suggesting that complete recoveries are attainable.

Effects of particulate matter exposure on the expression of the SARS-CoV-2 ACE2 receptor in ocular surface tissues and cells

Particulate matter (PM) has been reported to be one of the risk factor for COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, although the ocular surface is deeply affected by both PM exposure and SARS-COV-2 infection, no studies have investigated the effects of PM exposure on the ocular route of SARS-COV-2 infection. To this end, we explored the effects of PM on the expression of SARS-COV-2-associated receptors and proteins in ocular surface. Herein, short- and long-term PM-exposed rat models were established by topically administering PM for 3 and 10 days, respectively. Immortalized human corneal epithelial cells (HCECs) and human conjunctival epithelial cells (HCjECs) were exposed to PM. ACE2, TMPRSS2, CD147, and ADAM17 expression levels were measured by western blot analysis. Our results show that short-term PM exposure had little effect on the expressions of ACE2, TMPRSS2, and CD147 in ocular surface tissues. However, long-term PM exposure decreased the ACE2 expression in conjunctival tissues and increased the CD147 expression in corneal or conjunctival tissues. PM exposure reduced the ACE2 expression by increasing the ADAM17 expression and ACE2 shedding level in HCECs and HCjECs. Our findings suggest that long-term PM exposure down-regulate the expression of the SARS-CoV-2 receptor ACE2 in conjunctival tissues through ADAM17-dependent ACE2 shedding. However, long-term PM exposure up-regulates the expression of another SARS-CoV-2 receptor CD147 in ocular surface tissues, accompanied by ocular surface damage and cytotoxicity. This study provides a new insight into uncovering potential risk factors for infection with SARS-CoV-2 via the ocular route.

Bilateral Acute Macular Neuroretinopathy (AMN) after COVID-19 and its Clinical Course

Acute macular neuroretinopathy (AMN) is a rare disease entity. It is mainly observed in young women with a history of influenza-like infection or who have been taking oral contraceptives for several years. Patients typically describe subjective visual deterioration and mono- or bilateral paracentral relative scotomas. In some cases, funduscopic ophthalmic examination may reveal subtle sharply demarcated flat lesions of reddish-brown or orange colour in the macular region. Diagnosis is usually made by near-infrared fundus imaging which shows hyporeflective areas, and SD-OCT imaging which manifests changes in the outer retinal layers. In the following, three patient cases with bilateral AMN are described which occurred in direct temporal relationship to a recent SARS-CoV-2 infection.

Molecular insights to the anti-COVID-19 potential of α-, β- and γ-cyclodextrins

SARS-CoV-2 viral infection is regulated by the host cell receptors ACE2 and TMPRSS2, and therefore the effect of various natural and synthetic compounds on these receptors has recently been the subject of investigations. Cyclodextrins, naturally occurring polysaccharides derived from starch, are soluble in water and have a hydrophobic cavity at their center enabling them to accommodate small molecules and utilize them as carriers in the food, supplements, and pharmaceutical industries to improve the solubility, stability, and bioavailability of target compounds. In the current study, computational molecular simulations were used to investigate the ability of α-, β- and γ-Cyclodextrins on human cell surface receptors. Cell-based experimental approaches, including expression analyses at mRNA and protein levels and virus replication, were used to assess the effect on receptor expression and virus infection, respectively. We found that none of the three CDs could dock effectively to human cell surface receptor ACE2 and viral protease Mpro (essential for virus replication). On the other hand, α- and β-CD showed strong and stable interactions with TMPRSS2, and the expression of both ACE2 and TMPRSS2 was downregulated at the mRNA and protein levels in cyclodextrin (CD)-treated cells. A cell-based virus replication assay showed ∼20% inhibition by β- and γ-CD. Taken together, the study suggested that (i) downregulation of expression of host cell receptors may not be sufficient to inhibit virus infection (ii) activity of the receptors and virus protein Mpro may play a critical and clinically relevant role, and hence (iii) newly emerging anti-Covid-19 compounds warrant multimodal functional analyses.Communicated by Ramaswamy H. Sarma.

Human motor neurons derived from induced pluripotent stem cells are susceptible to SARS-CoV-2 infection

Introduction

COVID-19 typically causes Q7 respiratory disorders, but a high proportion of patients also reports neurological and neuromuscular symptoms during and after SARSCoV-2 infection. Despite a number of studies documenting SARS-CoV-2 infection of various neuronal cell populations, the impact of SARS-CoV-2 exposure on motor neuronal cells specifically has not been investigated so far.

Methods

Thus, by using human iPSC-derived motor neurons (iPSC-MNs) we assessed: (i) the expression of SARS-CoV-2 main receptors; (ii) iPSC-MN infectability by SARS-CoV-2; and (iii) the effect of SARS-CoV-2 exposure on iPSC-MN transcriptome.

Results

Gene expression profiling and immunofluorescence (IF) analysis of the main host cell receptors recognized by SARS-CoV-2 revealed that all of them are expressed in iPSC-MNs, with CD147 and NRP1 being the most represented ones. By analyzing SARS-CoV-2 N1 and N2 gene expression over time, we observed that human iPSC-MNs were productively infected by SARS-CoV-2 in the absence of cytopathic effect. Supernatants collected from SARS-CoV-2-infected iPSC-MNs were able to re-infect VeroE6 cells. Image analyses of SARS-CoV-2 nucleocapsid proteins by IF confirmed iPSC-MN infectability. Furthermore, SARS-CoV-2 infection in iPSCMNs significantly altered the expression of genes (IL-6, ANG, S1PR1, BCL2, BAX, Casp8, HLA-A, ERAP1, CD147, MX1) associated with cell survival and metabolism, as well as antiviral and inflammatory response.

Discussion

These results suggest for the very first time that SARS-CoV-2 can productively infect human iPSC-derived MNs probably by binding CD147 and NRP1 receptors. Such information will be important to unveil the biological bases of neuromuscular disorders characterizing SARS-CoV-2 infection and the so called long-COVID symptoms.

Expression of angiotensin converting enzyme 2 mRNA in different SARS-CoV-2 infection states and times

To measure the expression of angiotensin converting enzyme 2 (ACE2) mRNA in SARS-CoV-2 infection with different infection status and at different stages during infection, we used RT-qP CR to measure the expression of ACE2 mRNA. Measurements were analyzed by two-way repeated measures analysis of variance (RMANOVA). Expression of ACE2 mRNA was downregulated in initial stages of SARS-CoV-2 infection both in the asymptomatic infection (ASY) group and the confirmed cases (CON) group (t=-8.0845, P < 0.0001; t=-8.1904, P < 0.0001, respectively). The expression of ACE2 mRNA in the incubation period of CON group was lower compared with the intinal period of ASY group (F = 6.084, p = 0.016, partialη2 = 0.070). Relative expression of ACE2 mRNA was upregulated at the late stage of SARS-CoV-2 infection in the ASY and CON groups (F = 23.489, p = 0.000, partialη2 = 0.225; F = 46.555, p = 0.000, partialη2 = 0.365, respectively). The relative expression of ACE2 mRNA was down-regulated (mean ± SEM:0.69 ± 0.03) after inoculation with SARSCoV- 2 Spike pseudovirus, and there was a statistical difference (one-way t test, mean diffience =-0.31, 95%CI: -0.37˜-0.24, t=-8.1904, P < 0.0001). The expression of ACE2 mRNA is downregulated in the initial stage of SARS-CoV-2 infection, and then upregulated in the late stage of SARS-CoV-2 infection. The lower expression of ACE2 mRNA during the incubation period can lead to clinical symptoms. Downregulation of ACE2 mRNA was related to the interaction between SARS-CoV-2 S protein and ACE2.Communicated by Ramaswamy H. Sarma.

COVID-19 and Alzheimer's Disease Share Common Neurological and Ophthalmological Manifestations: A Bidirectional Risk in the Post-Pandemic Future

A growing body of evidence indicates that a neuropathological cross-talk takes place between the coronavirus disease 2019 (COVID-19) -the pandemic severe pneumonia that has had a tremendous impact on the global economy and health since three years after its outbreak in December 2019- and Alzheimer's Disease (AD), the leading cause of dementia among human beings, reaching 139 million by the year 2050. Even though COVID-19 is a primary respiratory disease, its causative agent, the so-called Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), is also endowed with high neuro-invasive potential (Neurocovid). The neurological complications of COVID-19, resulting from the direct viral entry into the Central Nervous System (CNS) and/or indirect systemic inflammation and dysregulated activation of immune response, encompass memory decline and anosmia which are typically associated with AD symptomatology. In addition, patients diagnosed with AD are more vulnerable to SARS-CoV-2 infection and are inclined to more severe clinical outcomes. In the present review, we better elucidate the intimate connection between COVID-19 and AD by summarizing the involved risk factors/targets and the underlying biological mechanisms shared by these two disorders with a particular focus on the Angiotensin-Converting Enzyme 2 (ACE2) receptor, APOlipoprotein E (APOE), aging, neuroinflammation and cellular pathways associated with the Amyloid Precursor Protein (APP)/Amyloid beta (Aβ) and tau neuropathologies. Finally, the involvement of ophthalmological manifestations, including vitreo-retinal abnormalities and visual deficits, in both COVID-19 and AD are also discussed. Understanding the common physiopathological aspects linking COVID-19 and AD will pave the way to novel management and diagnostic/therapeutic approaches to cope with them in the post-pandemic future.

Update on coronavirus disease 2019: Ophthalmic Manifestations and Adverse Reactions to Vaccination

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 was one of the most devastating public health issues in recent decades. The ophthalmology community is as concerned about the COVID-19 pandemic as the global public health community is, as COVID-19 was recognized to affect multiple organs in the human body, including the eyes, early in the course of the outbreak. Ophthalmic manifestations of COVID-19 are highly variable and could range from mild ocular surface abnormalities to potentially sight and life-threatening orbital and neuro-ophthalmic diseases. Furthermore, ophthalmic manifestations may also be the presenting or the only findings in COVID-19 infections. Meanwhile, global vaccination campaigns to attain herd immunity in different populations are the major strategy to mitigate the pandemic. As novel vaccinations against COVID-19 emerged, so were reports on adverse ophthalmic reactions potentially related to such. As the world enters a post-pandemic state where COVID-19 continues to exist and evolve as an endemic globally, the ophthalmology community ought to be aware of and keep abreast of the latest knowledge of ophthalmic associations with COVID-19 and its vaccinations. This review is a summary of the latest literature on the ophthalmic manifestations of COVID-19 and the adverse ophthalmic reactions related to its vaccinations.

Examination of the Corneal Endothelium in Pediatric Patients With COVID-19

PURPOSE

To investigate the effects of coronavirus disease 2019 (COVID-19) infection on the corneal endothelium in children.

METHODS

This retrospective study included 46 pediatric patients with COVID-19 infection and 38 healthy controls. Specular microscopy measurements were analyzed, and measurements were obtained from images showing at least 100 cells with clear borders. Mean endothelial cell density, mean hexagonal cell percentage (HEX), mean coefficient of variation (CV), central corneal thickness, and mean cell area were evaluated.

RESULTS

Specular microscopy data showed that the CV values were 2.442±6.517 in the healthy control group (HCG) and 2.659±5.119 in the COVID-19-affected group (CAG) ( P =0.003). The hexagonality of the HCG and CAG were 6.916±8.271 and 6.683±5.885, respectively ( P =0.011).

CONCLUSION

A decrease in the HEX and an increase in the CV were observed in the corneal specular microscopic examination of children with COVID-19 infection. These results are important in demonstrating the corneal effects of COVID-19 infection in children.

Single-Cell RNA Sequencing of Coronary Perivascular Adipose Tissue From End-Stage Heart Failure Patients Identifies SPP1+ Macrophage Subpopulation as a Target for Alleviating Fibrosis

BACKGROUND

Perivascular adipose tissue (PVAT) is vital for vascular homeostasis, and PVAT dysfunction is associated with increased atherosclerotic plaque burden. But the mechanisms underlining coronary PVAT dysfunction in coronary atherosclerosis remain elusive.

METHODS

We performed single-cell RNA sequencing of the stromal vascular fraction of coronary PVAT from 3 groups of heart transplant recipients with end-stage heart failure, including 3 patients with nonobstructive coronary atherosclerosis, 3 patients with obstructive coronary artery atherosclerosis, and 4 nonatherosclerosis control subjects. Bioinformatics was used to annotate the cellular populations, depict the cellular developmental trajectories and interactions, and explore the differences among 3 groups of coronary PVAT at the cellular and molecular levels. Pathological staining, quantitative real-time polymerase chain reaction, and in vitro studies were performed to validate the key findings.

RESULTS

Ten cell types were identified among 67 936 cells from human coronary PVAT. Several cellular subpopulations, including SPP1+ (secreted phosphoprotein 1) macrophages and profibrotic fibroadipogenic progenitor cells, were accumulated in PVAT surrounding atherosclerotic coronary arteries compared with nonatherosclerosis coronary arteries. The fibrosis percentage was increased in PVAT surrounding atherosclerotic coronary arteries, and it was positively associated with the grade of coronary artery stenosis. Cellular interaction analysis suggested OPN (osteopontin) secreted by SPP1+ macrophages interacted with CD44 (cluster of differentiation 44)/integrin on fibroadipogenic progenitor cells. Strikingly, correlation analyses uncovered that higher level of SPP1 in PVAT correlates with a more severe fibrosis degree and a higher coronary stenosis grade. In vitro studies showed that conditioned medium from atherosclerotic coronary PVAT promoted the migration and proliferation of fibroadipogenic progenitor cells, while such effect was prevented by blocking CD44 or integrin.

CONCLUSIONS

SPP1+ macrophages accumulated in the PVAT surrounding atherosclerotic coronary arteries, and they promoted the migration and proliferation of fibroadipogenic progenitor cells via OPN-CD44/integrin interaction and thus aggravated the fibrosis of coronary PVAT, which was positively correlated to the coronary stenosis burden. Therefore, SPP1+ macrophages in coronary PVAT may participate in the progression of coronary atherosclerosis.

Bilateral interstitial keratitis following COVID-19: a case report

BACKGROUND

Although the primary target of severe acute respiratory syndrome coronavirus 2 is the respiratory tract, the expression of the angiotensin-converting enzyme 2 receptor in other tissues facilitates viral entry in others parts of the body, including ocular structures. Ocular manifestations may occur before, during, or after systemic infection.

CASE PRESENTATION

We report the case of a 60-year-old male who presented with bilateral interstitial keratitis after the onset of COVID-19, with ocular symptoms starting within 7 days after systemic symptoms. Laboratory investigation did not identify any alternative etiology for his disease, although the possibility of Epstein-Barr virus or herpes simpex virus could not be definitively ruled out. The patient had already developed significant corneal scarring and visual debilitation by the time topical steroids were initiated, and his final corrected visual acuity with rigid gas permeable contact lenses was 20/50 and 20/80 in the right and left eye, respectively.

CONCLUSIONS

The involvement of ocular tissue by the virus can lead to permanent sequelae such as severe visual loss, and clinicians should be aware of and recognize ophthalmic manifestations of this disease to prompt early intervention.

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.

Considerations of COVID-19 in Ophthalmology

Since its emergence in early 2020, the SARS-CoV-2 infection has had a significant impact on the entire eye care system. Ophthalmologists have been categorized as a high-risk group for contracting the virus due to the belief that the eye may be a site of inoculation and transmission of the SARS-CoV-2 infection. As a result, clinical ophthalmologists, optometrists, and eyecare professionals have had to familiarize themselves with the ocular manifestations of COVID-19, as well as its treatments and vaccines. The implementation of measures to prevent the transmission of the virus, such as restrictions, lockdowns, telemedicine, and artificial intelligence (AI), have led to substantial and potentially irreversible changes in routine clinical practice, education, and research. This has resulted in the emergence of a new mode of managing patients in a routine clinical setting. This brief review aims to provide an overview of various aspects of COVID-19 in ophthalmology, including the ocular manifestations related to the disease, the modes of transmission of SARS-CoV-2 infection, precautions taken in ophthalmic practice to prevent the spread of the virus, drugs, and vaccines used in the treatment of COVID-19, the impact of the pandemic on patients, clinicians, and the eye care system as a whole, and the future of ophthalmology conditioned by this global pandemic experience.

The Role of Telemedicine in Glaucoma Care Triggered by the SARS-CoV-2 Pandemic: A Qualitative Study

Purpose

To explore and report on how glaucoma care was impacted by the SARS-CoV-2 pandemic (COVID-19) in New York City (NYC) with a specific emphasis on the role of telemedicine.

Patients and Methods

This was a qualitative, cross-sectional study that engaged glaucoma clinicians in semi-structured interviews to elicit perspectives on telemedicine and patient care experiences during the pandemic. Interview responses were coded and analyzed thematically.

Results

Twenty clinicians participated. Mean participant age was 48.8 ± 12.3 years, and the mean number of years in practice post-glaucoma fellowship was 17.5 ± 12.4 years. Four main themes pertinent to the role of telemedicine triggered by the COVID-19 pandemic were identified: (1) The Need to Ensure Patient and Staff Safety Drove Telemedicine Uptake; (2) Telemedicine Allowed Providers to Address Subjective Complaints; (3) Telemedicine was Discontinued Due To Concerns of Compromised Patient Safety and Measurement Inaccuracy; (4) Technological Advances are Needed for Continued Telemedicine Usage and Uptake in Glaucoma Care. The interviews suggested that telemedicine usage dropped markedly within just a few months during the pandemic, and for most physicians interviewed, telemedicine is no longer part of their clinical practice. Several clinicians reported optimism towards future implementation of telemedicine as the technology develops.

Conclusion

This study identified 4 themes outlining the uptake, application, discontinuation and overall perspectives on telemedicine by glaucoma clinicians. The role of telemedicine, as triggered by the COVID-19 pandemic, may have lasting implications for patient safety, continuity of care, and glaucoma care delivery beyond this public health crisis.

Arteritic Anterior Ischemic Optic Neuropathy (AAION) Associated with COVID-19 Infection: A Case Report and Review of the Literature

Anterior ischemic optic neuropathy (AION) is the most frequent cause of acute optic nerve damage in the elderly, usually causing acute, unilateral, and painless permanent visual loss. Arteritic anterior ischemic optic neuropathy (AAION) is a result of endothelial cell inflammation and the subsequent thrombosis and occlusion in the blood-supplying arteries of the optic nerve head. AAION accounts only for 5-10% of all AION cases that are associated with vasculitis which usually takes place in the course of a giant cell arteritis (GCA). In this paper, we report a case of AAION following a COVID-19 respiratory infection. Although it is uncertain whether SARS-CoV-2 infection triggered the AAION or was coincidental, the possible association of the events is concerning.

Knockout of angiotensin converting enzyme-2 receptor leads to morphological aberrations in rodent olfactory centers and dysfunctions associated with sense of smell

Neuronal morphological characterization and behavioral phenotyping in mouse models help dissecting neural mechanisms of brain disorders. Olfactory dysfunctions and other cognitive problems were widely reported in asymptomatic carriers and symptomatic patients infected with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). This led us to generate the knockout mouse model for Angiotensin Converting Enzyme-2 (ACE2) receptor, one of the molecular factors mediating SARS-CoV-2 entry to the central nervous system, using CRISPR-Cas9 based genome editing tools. ACE2 receptors and Transmembrane Serine Protease-2 (TMPRSS2) are widely expressed in the supporting (sustentacular) cells of human and rodent olfactory epithelium, however, not in the olfactory sensory neurons (OSNs). Hence, acute inflammation induced changes due to viral infection in the olfactory epithelium may explain transient changes in olfactory detectabilities. As ACE2 receptors are expressed in different olfactory centers and higher brain areas, we studied the morphological changes in the olfactory epithelium (OE) and olfactory bulb (OB) of ACE2 KO mice in comparison with wild type animals. Our results showed reduced thickness of OSN layer in the OE, and a decrease in cross-sectional area of glomeruli in the OB. Aberrations in the olfactory circuits were revealed by lowered immunoreactivity toward microtubule associated protein 2 (MAP2) in the glomerular layer of ACE2 KO mice. Further, to understand if these morphological alterations lead to compromised sensory and cognitive abilities, we performed an array of behavioral assays probing their olfactory subsystems' performances. ACE2 KO mice exhibited slower learning of odor discriminations at the threshold levels and novel odor identification impairments. Further, ACE2 KO mice failed to memorize the pheromonal locations while trained on a multimodal task implying the aberrations of neural circuits involved in higher cognitive functions. Our results thus provide the morphological basis for the sensory and cognitive disabilities caused by the deletion of ACE2 receptors and offer a potential experimental approach to study the neural circuit mechanisms of cognitive impairments observed in long COVID.

Supramolecular Nanofibers Block SARS-CoV-2 Entry into Human Host Cells

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection relies on its spike protein binding to angiotensin-converting enzyme 2 (ACE2) on host cells to initiate cellular entry. Blocking the interactions between the spike protein and ACE2 offers promising therapeutic opportunities to prevent infection. We report here on peptide amphiphile supramolecular nanofibers that display a sequence from ACE2 in order to promote interactions with the SARS-CoV-2 spike receptor binding domain. We demonstrate that displaying this sequence on the surface of supramolecular assemblies preserves its α-helical conformation and blocks the entry of a pseudovirus and its two variants into human host cells. We also found that the chemical stability of the bioactive structures was enhanced in the supramolecular environment relative to the unassembled peptide molecules. These findings reveal unique advantages of supramolecular peptide therapies to prevent viral infections and more broadly for other targets as well.

Ophthalmic Presentations and Manifestations of COVID-19: A Systematic Review of Global Observations

As the presentations and complications of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to surface, the ocular manifestations have emerged as an area of interest. Research and reports conveyed the presence of several ophthalmic conditions observed in Coronavirus disease 2019 (COVID-19) patients. These publications documented a range of presentations varying from asymptomatic to serious impairments. The aim of this study is to characterize the ophthalmic pathologies and their frequencies observed due to COVID-19 in patients across different regions of the world. The goal is that the paper assists primary care physicians and healthcare providers. A systematic review of 31 articles published between January 1, 2021 to January 13, 2022, explored the presenting ocular symptoms of COVID-19, diagnosis, duration of ophthalmic complications, as well as pre-existing comorbidities. A total of 816 patients, 427 (52.3%) males and 389 (47.7%) females, from various regions of the world were investigated. Studies focusing on patients with a history of ocular pathologies, non-COVID-19 infections, complications associated with the COVID-19 vaccine, and pediatric patients were excluded from this study. Ocular complications were most commonly reported one to two weeks following the initial COVID-19 diagnosis. Analysis suggests that the "red" eye is the most prevalent presenting ophthalmologic symptom, followed by temporary vision loss. Conjunctivitis was also the most common clinical diagnosis reported, followed by neuro-retinal affection in the form of cotton wool spots (n=127 and n=9, respectively). This study summarizes ocular manifestations in COVID-19 patients and serves to help healthcare providers recognize common symptoms and their severity. This may lead to early diagnosis, treatment, and intervention of these manifestations.

Reduced Vessel Density and Enlarged Foveal Avascular Zone in the Macula as a Result of Systemic Hypoxia Caused by SARS-CoV-2 Infection

Infection with SARS-CoV-2 can lead to various long-term consequences, including those of an ophthalmic nature. This paper reviews the results of optical coherence tomography angiography (OCTA) performed among COVID-19 patients. The review included papers evaluating short- and long-term outcomes following the SARS-CoV-2 infection. Some differentiated the obtained retinal and choroidal vascularization parameters according to gender. Following COVID-19, patients reveal changes in retinal and choroidal vascular parameters based on OCTA, such as reduced vascular density and an increased foveal avascular zone, which can persist for several months. Routine ophthalmic follow-up with OCTA should be considered in patients after SARS-CoV-2 infection to assess the effects of inflammation and systemic hypoxia in COVID-19. Further research is needed to understand whether infection with particular viral variants/subvariants may vary in the risk of effects on retinal and choroidal vascularization and whether and to what extent these risks may also differ in relation to reinfected and vaccinated individuals.

Review of Neurological Manifestations of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can affect any part of the neuraxis. Many neurological conditions have been attributed to be caused by SARS-CoV-2, namely encephalopathy (acute necrotizing encephalopathy and encephalopathy with reversible splenial lesions), seizures, stroke, cranial nerve palsies, meningoencephalitis, acute disseminated encephalomyelitis (ADEM), transverse myelitis (long and short segment), Guillain-Barré syndrome (GBS) and its variants, polyneuritis cranialis, optic neuritis (ON), plexopathy, myasthenia gravis (MG), and myositis. The pathophysiology differs depending on the time frame of presentation. In patients with concomitant pulmonary disease, for instance, acute neurological illness appears to be caused by endotheliopathy and cytokine storm. Autoimmunity and molecular mimicry are causative for post-coronavirus disease 2019 (COVID-19)-sequelae. It has not yet been shown that the virus can penetrate the central nervous system (CNS) directly. This review aims to describe the disease and root pathogenic cause of the various neurological manifestations of COVID-19. We searched Pubmed/Medline and Google Scholar using the keywords "SARS-CoV-2" and "neurological illness" for articles published between January 2020 and November 2022. Then, we used the SWIFT-Review (Sciome LLC, North Carolina, United States), a text-mining workbench for systematic review, to classify the 1383 articles into MeSH hierarchical tree codes for articles on various parts of the nervous system, such as the CNS, peripheral nervous system, autonomic nervous system, neuromuscular junction, sensory system, and musculoskeletal system. Finally, we reviewed 152 articles in full text. SARS-CoV-2 RNA has been found in multiple brain areas without any histopathological changes. Despite the absence of in vivo virions or virus-infected cells, CNS inflammation has been reported, especially in the olfactory bulb and brain stem. SARS-CoV-2 genomes and proteins have been found in affected individuals' brain tissues, but corresponding neuropathologic changes are seldom found in these cases. Additionally, viral RNA can rarely be identified in neurological patients' CSF post hoc SARS-CoV-2 infection. Most patients with neurological symptoms do not have active viral replication in the nervous system and infrequently have typical clinical and laboratory characteristics of viral CNS infections. Endotheliopathy and the systemic inflammatory response to SARS-CoV-2 infection play a crucial role in developing neuro-COVID-19, with proinflammatory cytokine release mediating both pathological pathways. The systemic inflammatory mediators likely activate astrocytes and microglia across the blood-brain barrier, indirectly affecting CNS-specific immune activation and tissue injury. The management differs according to co-morbidities and the neurological disorder.

Quantitative assessment of the effect of SARS-CoV-2 on the corneal sub-basal nerve plexus of post-COVID-19 patients using in vivo confocal microscopy

OBJECTIVES

To investigate whether SARS-CoV-2 causes morphological changes in the corneal sub-basal nerve plexus (CSNP) of post-COVID-19 patients using in vivo confocal microscopy (IVCM).

METHODS

A total of 70 participants were included in the study and were divided into three groups. Post-COVID-19 patients with neurological manifestations were considered Group 1 (n = 24), and post-COVID-19 patients without neurological manifestations were considered Group 2 (n = 24). Healthy control participants were considered Group 3 (n = 22). The parameters of the CSNP, including nerve fibre density (NFD), nerve branch density (NBD), and nerve fibre length (NFL), were investigated in all participants using IVCM. Additionally, corneal sensitivity was tested by corneal esthesiometry.

RESULTS

The mean NFD, NBD, and NFL values of Group 1 (16.12 ± 4.84 fibre/mm², 27.97 ± 9.62 branch/mm², and 11.60 ± 2.89 mm/mm²) were significantly lower than those of Group 2 (19.55 ± 3.01 fibre/mm², 40.44 ± 7.16 branch/mm², and 15.92 ± 2.08 mm/mm²) and Group 3 (25.24 ± 3.75 fibre/mm², 44.61 ± 11.80 branch/mm², and 17.76 ± 3.32 mm/mm²) (p < 0.05 for all). Except the mean NFD value (p < 0.001), there were no significant differences in terms of the mean NBD and NFL values between Group 2 and Group 3 (p = 0.445, p = 0.085). The value of the mean corneal sensitivity was significantly higher in Group 3 (59.09 ± 1.97 mm) compared to Group 1 (55.21 ± 1.02 mm) and Group 2 (55.28 ± 1.18 mm) (p < 0.001, p < 0.001) but there was no significant difference between Group 1 and Group 2 (p = 1.000).

CONCLUSION

In post-COVID-19 patients, the mean parameters of CSNP were lower than in the control group. These differences were more pronounced in patients who had neurological manifestations of COVID-19.

The Latest Cellular and Molecular Mechanisms of COVID-19 on Non-Lung Organs

Understanding the transmission pathways of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will aid in developing effective therapies directed at the virus’s life cycle or its side effects. While severe respiratory distress is the most common symptom of a coronavirus 2019 (COVID-19) infection, the virus is also known to cause damage to almost every major organ and system in the body. However, it is not obvious whether pathological changes in extra-respiratory organs are caused by direct infection, indirect, or combination of these effects. In this narrative review, we first elaborate on the characteristics of SARS-CoV-2, followed by the mechanisms of this virus on various organs such as brain, eye, and olfactory nerve and different systems such as the endocrine and gastrointestinal systems.

Investigation of changes in retinal vascular parameters and choroidal vascular index values during the early recovery period of COVID-19: The COVID-OCTA study

BACKGROUND

COVID-19 effects microvasculature in many tissues. This study investigated whether the choroidal structure is also affected.

METHODS

This cross-sectional study included 80 patients with COVID-19 and the same number of age- and gender-matched healthy individuals. All participants' right eye measurements were examined. Optical coherence tomography angiography (OCTA) was used for imaging. Otherwise, two independent researchers used the Choroidal vascular index (CVI) for choroidal parameters calculation.

RESULTS

Superior and deep flow values were lower in the COVID-19 group than in the control group, and vascular density (VD) values were lower in all regions in this group. Except for the superior mean VD, there was no statistically significant difference (p = 0.003). However, the COVID-19 group had significantly lower subfoveal choroidal thickness (SFChT) measurements than the control group (p = 0.001). In addition, no significant difference was observed between the groups in evaluating mean CVI values (p>0.05).

CONCLUSION

Noninvasive diagnostic tools such as OCTA and EDI-OCT can be used to monitor early changes in diseases affecting microvessels, such as from COVID-19.

Evaluation of Anti-SARS-CoV-2 IgA Response in Tears of Vaccinated COVID-19 Subjects

Secretory IgA (sIgA), which may play an important role in the early defense against SARS-CoV-2 infection, were detected in the eye of COVID-19 patients. However, an evaluation of the sIgA response in the tears of vaccinated or non-vaccinated COVID-19 subjects is still lacking. Aimed at characterizing sIgA mucosal immunity in the eye, this study analyzed tear samples from 77 COVID-19 patients, including 63 vaccinated and 14 non-vaccinated subjects. The groups showed similar epidemiological features, but as expected, differences were observed in the percentage of asymptomatic/pauci-symptomatic subjects in the vaccinated vs. non-vaccinated cohort (46% and 29% of the total, respectively). Consistent with this, ocular sIgA values, evaluated by a specific quantitative ELISA assay, were remarkably different in vaccinated vs. non-vaccinated group for both frequency (69.8% vs. 57.1%, respectively) and titer (1372.3 U/mL vs. 143.7 U/mL, respectively; p = 0.01), which was significantly differently elevated depending on the type of administered vaccine. The data show for the first time significant differences of available vaccines to elicit sIgA response in the eye and suggest that quantitative tear-based sIgA tests may potentially serve as a rapid and easily accessible biomarker for the assessment of the development of a protective mucosal immunity toward SARS-CoV-2.

Ocular Symptoms Associated with COVID-19 Are Correlated with the Expression Profile of Mouse SARS-CoV-2 Binding Sites

The COVID-19 pandemic has engendered significant scientific efforts in the understanding of its infectious agent SARS-CoV-2 and of its associated symptoms. A peculiar characteristic of this virus lies in its ability to challenge our senses, as its infection can lead to anosmia and ageusia. While ocular symptoms, such as conjunctivitis, optic neuritis or dry eyes, are also reported after viral infection, they have lower frequencies and severities, and their functional development is still elusive. Here, using combined technical approaches based on histological and gene profiling methods, we characterized the expression of SARS-CoV-2 binding sites (Ace2/Tmprss2) in the mouse eye. We found that ACE2 was ectopically expressed in subtissular ocular regions, such as in the optic nerve and in the Harderian/intraorbital lacrimal glands. Moreover, we observed an important variation of Ace2/Tmprss2 expression that is not only dependent on the age and sex of the animal, but also highly heterogenous between individuals. Our results thus give new insight into the expression of SARS-CoV-2 binding sites in the mouse eye and propose an interpretation of the human ocular-associated symptoms linked to SARS-CoV-2.

Absence of detectable SARS-CoV-2 replication in ex vivo cultured cornea and cornea-derived epithelial cells

PURPOSE

To study the possibility of SARS-CoV-2 to infect human corneal cells and tissues under standard corneal culture conditions using explants of COVID-19 donors and primary cornea-derived epithelial cells.

METHODS

Cornea isolated from deceased COVID-19 donors was cultured for 4 weeks, and SARS-CoV-2 replication was monitored by qRT-PCR. Furthermore, primary corneal epithelial cells from healthy donors were cultured ex vivo and infected with SARS-CoV-2 and human cytomegalovirus (HCMV) as a control. Infection status was assessed by western blotting and reporter gene expression using green fluorescent protein-expressing viral strains. ACE2 and TMPRSS2 receptor expression levels in cornea and epithelial cells were assessed by qRT-PCR.

RESULTS

We did not detect SARS-CoV-2 replication in 10 corneas isolated from deceased COVID-19 patients and cultured for 4 weeks, indicating absence of infection under natural conditions. Furthermore, high-titer SARS-CoV-2 infection of ex vivo cultured cornea-derived epithelial cells did not result in productive virus replication. In contrast, the same cells were highly permissive for HCMV. This phenotype could potentially be explained by low ACE2 and TMPRSS2 transcriptional activity in cornea and cornea-derived epithelial cells.

CONCLUSIONS

Our data suggest that cornea and limbal epithelial cells are refractory to productive SARS-CoV-2 infection. This could be due to the absence of robust receptor expression levels necessary for viral entry. This study adds further evidence to support the very low possibility of transmission of SARS-CoV-2 from an infected corneal transplant donor to a recipient in corneal organ cultures.

The causal relationship between COVID-19 and increased intraocular pressure: A bidirectional two-sample Mendelian randomization study

Background

Coronavirus disease 2019 (COVID-19) has brought great challenges to the global public health system and huge economic burdens to society, the causal effect of COVID-19 and intraocular pressure was blank.

Objective

This study aimed to explore the causal association between coronavirus disease (COVID-19) susceptibility, severity and criticality and intraocular pressure (IOP) by bidirectional Mendelian randomization (MR) analysis.

Materials and methods

Genetic associations with COVID-19 susceptibility, severity and criticality were obtained from the COVID-19 Host Genetics Initiative. Genetic associations with IOP were obtained from GWAS summary data. The standard inverse variance weighted (IVW) method was used in the primary assessment of this causality. Other methods were also implemented in supplementary analyses. Finally, sensitivity analysis was performed to evaluate the reliability and stability of the results.

Results

The results showed that COVID-19 susceptibility had null effect on IOP (β = 0.131; Se = 0.211; P = 0.533) as assessed by the IVW method. Moreover, the results revealed that COVID-19 severity, specifically, hospitalization due to COVID-19, had a positive effect on IOP with nominal significance (β = 0.228; Se = 0.116; P = 0.049). However, there were null effect of COVID-19 criticality on IOP (β = 0.078; Se = 0.065; P = 0.227). Sensitivity analysis showed that all the results were reliable and stable. The reverse MR analysis revealed that there was null effect of IOP on COVID-19.

Conclusions

We demonstrated that hospitalization due to COVID-19 might increase IOP; therefore, greater attention should be given to monitoring IOP in inpatients with COVID-19.

COVID-19 and Eye Banking: Ongoing Impacts of the Pandemic

PURPOSE

The purpose of this study was to assess the impact of ongoing waves of the COVID-19 pandemic and resulting guidelines on the corneal donor pool with resumption of clinical operations.

METHODS

A retrospective analysis of donors deemed eligible for corneal transplantation at an eye bank from July 1, 2020, through December 31, 2021. Donors ineligible due to meeting Eye Bank Association of America (EBAA) COVID-19 guidelines or a positive postmortem COVID-19 testing were examined. The correlation between COVID-19 rule outs and state COVID positivity was calculated. The number of scheduled surgeries, suitable corneas, imports, and international exports was compared with a pre-COVID period. Postmortem testing was reduced for the final 5 months of the study, and numbers were compared before and after the policy change.

RESULTS

2.85% of referrals to the eye bank were ruled out because of EBAA guidelines. 3.2% of postmortem tests were positive or indeterminate resulting in an ineligible tissue donor (0.42% of referrals). Over the 18-month period, there was a 4.30% shortage of suitable corneas compared with transplantation procedures. There was a significant correlation between postmortem testing and state COVID-19 positivity (r = 0.37, P <0.01), but not with EBAA guidelines (r = 0.19, P = 0.07). When postmortem testing was reduced, significantly more corneas were exported internationally.

CONCLUSIONS

Although corneal transplant procedures were back to normal levels, there was a shortage of suitable corneal tissue. The discontinuation of postmortem testing was associated with a significant increase in international exports of corneal donor tissue.

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.

Ocular tropism of SARS-CoV-2 in animal models with retinal inflammation via neuronal invasion following intranasal inoculation

Although ocular manifestations are reported in patients with COVID-19, consensus on ocular tropism of SARS-CoV-2 is lacking. Here, we infect K18-hACE2 transgenic mice with SARS-CoV-2 using various routes. We observe ocular manifestation and retinal inflammation with production of pro-inflammatory cytokines in the eyes of intranasally (IN)-infected mice. Intratracheal (IT) infection results in dissemination of the virus from the lungs to the brain and eyes via trigeminal and optic nerves. Ocular and neuronal invasions are confirmed using intracerebral (IC) infection. Notably, the eye-dropped (ED) virus does not cause lung infection and becomes undetectable with time. Ocular and neurotropic distribution of the virus in vivo is evident in fluorescence imaging with an infectious clone of SARS-CoV-2-mCherry. The ocular tropic and neuroinvasive characteristics of SARS-CoV-2 are confirmed in wild-type Syrian hamsters. Our data can improve the understanding regarding viral transmission and clinical characteristics of SARS-CoV-2 and help in improving COVID-19 control procedures.