Herpes simplex keratitis: challenges in diagnosis and clinical management

Clinical strategies to prevent recurrence of Herpes simplex and Herpes zoster following ocular surgery: A comprehensive review with practical guidelines

Recurrences of herpetic infections following intraocular surgeries pose a threat to optimal surgical outcomes. The high prevalence of herpetic diseases require ophthalmologists to be familiar with the special measures in the surgery of these patients. A thorough preoperative assessment and meticulous postoperative surveillance should be tailored for each patient, depending on the surgery and the risk of virus reactivation. We compile the relevant evidence in the literature and provide a comprehensive review of the preoperative assessment and postoperative diagnostic clues and management of the herpetic infections following different types of intraocular surgeries, including cataract surgery, keratoplasty, corneal crosslinking, glaucoma, and refractive surgeries.

Fungal infection monitoring on corneal epithelium ex vivo model and its collection over polyethersulfone membrane for detecting Candida albicans and Aspergillus fumigatus

In this paper we report a human ex vivo model of Aspergillus fumigatus and Candida albicans infection of the cornea. We demonstrate the ability to monitor fungal growth on the cornea through optical and immunofluorescence microscopy. Additionally, we establish a method for collection of fungal antigens in polyethersulfone (PES) membrane-based sample collectors from the surface of fungal inoculated corneas. Immunofluorescence microscopy was performed directly on both corneal tissue and PES membrane sample collectors. For the latter case, we devised an original ad-hoc method by attaching the membranes used for the collection on standard glass slides, which we call glass slide KIT. This enabled easy handling and improved efficiency for specifically recognizing the corresponding fungal infections by simple immunoassay protocols. As a result, we firstly observe the ability to monitor fungi in corneal tissue, and secondly demonstrate the adsorption of fungal antigens onto PES membranes. Thus, we report for the first time the specific detection of fungal corneal infections in easy to use PES membrane based glass slide KITs through simple immunofluorescence, as an alternative to microbiological culture.

Kaposi's Varicelliform Eruption: A Serious and Potentially Fatal Complication of Darier's Disease

Darier's disease (DD) is an autosomal dominant genetic disorder characterized by skin barrier dysfunction and chronic skin inflammation predisposing patients to secondary infections. Kaposi's varicelliform eruption (KVE), a severe viral infection, most commonly caused by herpes simplex virus (HSV), represents a life-threatening complication in these patients. The authors present the case of a 48-year-old woman with DD, who developed a progressive painful vesiculopustular eruption accompanied by systemic symptoms, including fever, bilateral otalgia, and ocular pain. The initial skin lesions, confined to the scapular region, rapidly spread to the face, periorbital region, and external ears. Clinical examination revealed vesiculopustular lesions, conjunctival hyperemia, and ear involvement. Laboratory testing confirmed HSV-1/2 immunoglobulin M (IgM) positivity, and blood cultures grew Staphylococcus aureus, indicating bacterial superinfection. The patient was treated with intravenous acyclovir and flucloxacillin, leading to significant clinical improvement. Clinicians should maintain a high index of suspicion for KVE in patients with DD presenting with vesicular rashes, particularly when systemic symptoms or rapid progression is observed. This case underscores the importance of early recognition of KVE in DD patients to facilitate timely antiviral and antibacterial treatment, reducing the risk of severe complications such as vision loss and permanent auditory impairment.

γδ T17 Cells Regulate the Acute Antiviral Response of NK Cells in HSV-1-Infected Corneas

Purpose

To determine whether γδ T cells regulate natural killer (NK) cells in the herpes simplex virus 1 (HSV-1)-infected cornea.

Methods

CD57Bl/6 (wild-type [WT]), TCRδ-/-, and IFN-γ-/- mice were infected intracorneally with HSV-1. TCR-/- mice were treated with IL-17A at 24 hours post-infection (PI), and the WT mice received treatments of fingolimod (FTY720) and anti-IL-17A. At 48 hours PI, corneas were excised, and intracellular staining flow cytometry was performed, as well as multiplex analysis. Additionally, single-cell RNA sequencing (scRNAseq) was done to analyze the transcriptome of NK cells from WT and TCRδ-/- mice.

Results

In mice lacking γδ T cells, there were significantly fewer NK cells following ocular HSV-1 infection. This reduction of NK cells corresponded with lower levels of cytokines and chemokines associated with the antiviral response. Furthermore, NK cells from WT mice had enriched IL-17A signaling compared to those from TCRδ-/- mice. The NK cell response was partially rescued in TCRδ-/- mice by administration of IL-17A. Correspondingly, the NK cell response could be blunted in WT mice by administration of anti-IL-17A. Finally, IFN-γ-/- mice had significantly less IL-17A production compared to WT mice.

Conclusions

γδ T17 cells promote NK cell accumulation in HSV-1-infected corneas. In turn, NK cells secrete IFN-γ, which negatively regulates further IL-17A production by γδ T cells.

The immunobiology of corneal HSV-1 infection and herpetic stromal keratitis

SUMMARYHuman alphaherpesvirus 1 (HSV-1) is a highly successful neurotropic pathogen that primarily infects the epithelial cells lining the orofacial mucosa. After primary lytic replication in the oral, ocular, and nasal mucosal epithelial cells, HSV-1 establishes life-long latency in neurons within the trigeminal ganglion. Patients with compromised immune systems experience frequent reactivation of HSV-1 from latency, leading to virus entry in the sensory neurons, followed by anterograde transport and lytic replication at the innervated mucosal epithelial surface. Although recurrent infection of the corneal mucosal surface is rare, it can result in a chronic immuno-inflammatory condition called herpetic stromal keratitis (HSK). HSK leads to gradual vision loss and can cause permanent blindness in severe untreated cases. Currently, there is no cure or successful vaccine to prevent latent or recurrent HSV-1 infections, posing a significant clinical challenge to managing HSK and preventing vision loss. The conventional clinical management of HSK primarily relies on anti-virals to suppress HSV-1 replication, anti-inflammatory drugs (such as corticosteroids) to provide symptomatic relief from pain and inflammation, and surgical interventions in more severe cases to replace damaged cornea. However, each clinical treatment strategy has limitations, such as local and systemic drug toxicities and the emergence of anti-viral-resistant HSV-1 strains. In this review, we summarize the factors and immune cells involved in HSK pathogenesis and highlight alternate therapeutic strategies for successful clinical management of HSK. We also discuss the therapeutic potential of immunoregulatory cytokines and immunometabolism modulators as promising HSK therapies against emerging anti-viral-resistant HSV-1 strains.

RTP4 Enhances Corneal HSV-1 Infection in Mice With Type 2 Diabetes Mellitus

Purpose

The purpose of this study was to investigate whether corneal lesions in mice with type 2 diabetes mellitus (T2D) infected with herpes simplex virus (HSV)-1 are more severe, and to elucidate the specific underlying mechanism.

Methods

The corneas of control mice and T2D mice induced by a high-fat diet combined with streptozotocin were infected with the HSV-1 Mckrae strain to assess corneal infection, opacity, and HSV-1 replication. RNA sequencing of the corneal epithelium from wild-type and db/db mice (a genetic T2D mouse model) was conducted to identify the key gene affecting T2D infection. Immunofluorescence staining was performed on corneal sections from T2D mice and patients with T2D. The effect of small interfering RNA (siRNA) knockdown on corneal HSV-1 infection was evaluated in both in vitro and in vivo models.

Results

T2D mice exhibited a more severe infection phenotype following HSV-1 infection, characterized by augmented corneal opacity scores, elevated viral titers, and transcripts compared to control mice. Transcriptome analysis of corneal epithelium revealed a hyperactive viral response in T2D mice, highlighting the differentially expressed gene Rtp4 (encoding receptor transporter protein 4). Receptor transporter protein 4 (RTP4) expression was enhanced in the corneal epithelium of T2D mice and patients with T2D. Virus binding assays demonstrated that RTP4 facilitated HSV-1 binding to human corneal epithelial cells. Silencing RTP4 alleviated HSV-1 infection in both in vitro and in vivo T2D models.

Conclusions

The findings indicate that elevated RTP4 exacerbates HSV-1 infection by enhancing its binding to corneal epithelial cells, whereas Rtp4 knockdown mitigated corneal lesions in T2D mice. This implies RTP4 as a potential target for intervention in diabetic HSV-1 infection.

Outcomes of Corneal Transplantation for Herpetic Keratitis: A Narrative Review

Herpes simplex virus (HSV) is one of the most common etiologic agents of corneal disease and a significant cause of corneal blindness worldwide. Although most cases can be successfully managed with medical therapy, HSV keratitis associated with visually significant stromal scarring often requires corneal transplantation for visual rehabilitation. While penetrating keratoplasty (PK) represented the traditional keratoplasty technique, the past few decades have seen a shift towards lamellar keratoplasty procedures, including deep anterior lamellar keratoplasty and mushroom keratoplasty. This paper describes the current surgical techniques and perioperative antiviral prophylaxis regimen for herpetic keratitis and reviews their postoperative clinical outcomes.

Influence of different parameters on the corneal asphericity (Q value) assessed with progress in biomedical optics and imaging - A review

The corneal eye diseases such as Keratoconus cause weakening of the cornea, with this disease the cornea can change in shape. This condition affects between 1 in 3,000 to 1 in 10,000 people. The main reason for the development of such conditions is unknown and can have significant impacts. Over the last decade, with advancements in computerized corneal topography assessments, researchers have increasingly expressed interest in corneal topography for research as well as clinical activities. Up till now, several aspheric numerical models have been developed as well as proposed to define the complex shape of the cornea. A commonly used term for characterizing the asphericity in an eye is the Q value, a common indicator of the aspherical degree of the cornea. It is one of the critical parameters in the mathematical description model of the cornea as it represents the cornea's shape and the eye's characteristics. Due to the utmost importance of this Q value of the cornea, a couple of studies have attempted to explore this parameter and its distribution, merely in terms of its influence on the human eye's optical properties. The corneal Q value is an important factor that needs to be determined to treat for any refractive errors as corneal degeneration are disease that can lead to potential problems with the structure of the cornea. This study aims to highlight the need to understand Q value of the cornea as this can essentially assist with personalising corneal refractive surgeries and implantation of intraocular lenses. Therefore, the relevance of corneal Q value must be studied in association with different patients, especially ones who have been diagnosed with cataracts, brain tumours, or even COVID-19. To address this issue, this paper first carries out a literature review on the optics of the cornea, the relevance of corneal Q value in ophthalmic practice and studies corneal degenerations and its causes. Thereafter, a detailed review of several noteworthy relevant research studies examining the Q value of the cornea is performed. To do so, an elaborate database is created, which presents a list of different research works examined in this study and provides key evidence derived from these studies. This includes listing details on the age, gender, ethnicity of the eyes assessed, the control variables, the technology used in the study, and even more. The database also delivers important findings and conclusions noted in each study assessed. Next, this paper analyses and discusses the magnitude of corneal Q value in various scenarios and the influence of different parameters on corneal Q value. To design visual optical products as well as to enhance the understanding of the optical properties of an eye, future studies could consider the database and work presented in this study as useful references. In addition, the work can be used to make informed decisions in clinical practice for designing visual optical products as well as to enhance the understanding of the optical properties of an Eye.

Viral Keratitis, Surgical Intervention in Viral Keratitis, Challenges in Diagnosis and Treatment of Viral Keratitis, HSV, HZV

Viral keratitis is a significant cause of ocular morbidity and visual impairment worldwide. In recent years, there has been a growing understanding of the pathogenesis, clinical manifestations, and diagnostic modalities for viral keratitis. The most common viral pathogens associated with this condition are adenovirus, herpes simplex (HSV), and varicella-zoster virus (VZV). However, emerging viruses such as cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Vaccinia virus can also cause keratitis. Non-surgical interventions are the mainstay of treatment for viral keratitis. Antiviral agents such as Acyclovir, Ganciclovir, and trifluridine have effectively reduced viral replication and improved clinical outcomes. Additionally, adjunctive measures such as lubrication, corticosteroids, and immunomodulatory agents have alleviated symptoms by reducing inflammation and facilitating tissue repair. Despite these conservative approaches, some cases of viral keratitis may progress to severe forms, leading to corneal scarring, thinning, or perforation. In such instances, surgical intervention becomes necessary to restore corneal integrity and visual function. This review article aims to provide an overview of the current perspectives and surgical interventions in managing viral keratitis. The choice of surgical technique depends on the extent and severity of corneal involvement. As highlighted in this article, on-going research and advancements in surgical interventions hold promise for further improving outcomes in patients with viral keratitis.

Herpes simplex keratitis: A brief clinical overview

The aim of our minireview is to provide a brief overview of the diagnosis, clinical aspects, treatment options, management, and current literature available regarding herpes simplex keratitis (HSK). This type of corneal viral infection is caused by the herpes simplex virus (HSV), which can affect several tissues, including the cornea. One significant aspect of HSK is its potential to cause recurrent episodes of inflammation and damage to the cornea. After the initial infection, the HSV can establish a latent infection in the trigeminal ganglion, a nerve cluster near the eye. The virus may remain dormant for extended periods. Periodic reactivation of the virus can occur, leading to recurrent episodes of HSK. Factors triggering reactivation include stress, illness, immunosuppression, or trauma. Recurrent episodes can manifest in different clinical patterns, ranging from mild epithelial involvement to more severe stromal or endothelial disease. The severity and frequency of recurrences vary among individuals. Severe cases of HSK, especially those involving the stroma and leading to scarring, can result in vision impairment or even blindness in extreme cases. The cornea's clarity is crucial for good vision, and scarring can compromise this, potentially leading to visual impairment. The management of HSK involves not only treating acute episodes but also implementing long-term strategies to prevent recurrences and attempt repairs of corneal nerve endings via neurotization. Antiviral medications, such as oral Acyclovir or topical Ganciclovir, may be prescribed for prophylaxis. The immune response to the virus can contribute to corneal damage. Inflammation, caused by the body's attempt to control the infection, may inadvertently harm the corneal tissues. Clinicians should be informed about triggers and advised on measures to minimize the risk of reactivation. In summary, the recurrent nature of HSK underscores the importance of both acute and long-term management strategies to preserve corneal health and maintain optimal visual function.

UVB induced reactivation leads to HSV1 in the corneas of virtually all latently infected mice and requires STING to develop corneal disease

Reactivation of latent herpes simplex type 1 results in virus returning to the cornea leading to recurrent herpetic stromal keratitis (rHSK). We compare two competing models to reactivate viruses from latency, UV-B irradiation and cyclophosphamide (CP). Results revealed that while both result in corneal recrudescence, only UV-B irradiation results in rHSK. To better understand the dynamics of reactivation, we analyzed corneas for both the presence of infectious viruses and the dynamics of exposure to multiple reactivations using UV-B. We noted that multiple reactivations result in progressively worse corneal disease. We also noted that expression of IFNα and STING, surragate markers for the presence of virus, are induced by the presence of reactivated virus. Studies to determine the importance of STING to the development of HSK revealed that in the absence of STING, mice do not develop significant HSK and the magnitude of the infiltrate of CD45+ cells in these corneas is significantly reduced. The resulting paucity of CD45+CD11b+GR-1+F4/80-neutrophils, and to a lesser extent CD45+CD11b+GR-1-F4/80+ macrophages in B6-STING KO mice following reactivation is likely the underlying cause for lack of rHSK as has been noted by ourselves and others. These results underscore the critical importance of STING's role in developing rHSK.

Krupple-like factor 4 (KLF4) methylation signature in host cell in active viral keratitis with epithelial manifestation

HSV1 presents as epithelial or stromal keratitis or keratouveitis and can lead to sight-threatening complications. KLF4, a critical transcription factor, and regulator of cell growth and differentiation, is essential in corneal epithelium stratification and homeostasis. Here, we want to understand the epigenetic modification specifically the methylation status of KLF4 in epithelium samples of HSV1 keratitis patients. After obtaining consent, epithelial scrapes were collected from 7 patients with clinically diagnosed HSV1 keratitis and 7 control samples (patients undergoing photorefractive keratectomy). Genomic DNA was isolated from the collected samples using the Qiagen DNeasy Kit. Subsequently, bisulfite modification was performed. The bisulphite-modified DNA was then subjected to PCR amplification using specific primers designed to target the KLF4, ACTB gene region, allowing for the amplification of methylated and unmethylated DNA sequences. The amplified DNA products were separated and visualized on a 3% agarose gel. KLF4 hypermethylation was found in 6 out of 7 (85.71%) eyes with viral keratitis, while 1 eye showed hypomethylation compared to PRK samples. Out of these 6, there were 2 each of epithelial dendritic keratitis, epithelial geographical keratitis, and neurotrophic keratitis. The patient with hypomethylated KLF4 had a recurrent case of HSV1 keratitis with multiple dendrites and associated vesicular lesions of the lip along with a history of fever. KLF4 hypermethylation in most viral keratitis cases indicated the under functioning of KLF4 and could indicate a potential association between KLF4 hypermethylation and the development or progression of HSV1 keratitis.

Atopic Disease as a Risk Factor for Recurrent Herpetic Keratitis

Recurrent herpetic keratitis is a leading cause of blindness worldwide. In this population-based cross-sectional study, the medical records of Israeli adolescents and young adults who underwent systematic preconscription evaluation for mandatory military service were reviewed. The prevalence of atopic conjunctival disease was evaluated in cases with and without documented recurrent herpetic keratitis. The association was tested using uni- and multivariant analyses. Overall, 940,892 adolescents and young adults were included. The mean age was 17.57 ± 1.50 years (range 16-20 years), and 40.70% of participants were female. Recurrent herpetic keratitis was documented in 160 cases, with a prevalence of 0.017% in this age group. Compared to the general population, patients with recurrent herpetic keratitis were significantly more likely to be males (p = 0.003) with a concomitant diagnosis of atopic conjunctival disease (p < 0.0001). Patients with atopic conjunctival disease were 10.60-fold more likely to experience recurrent herpetic keratitis (95% confidence interval (CI): 6.76-16.64, p < 0.0001). Upon multivariate analysis, the results remained significant (p < 0.001). Cases of severe atopic conjunctival disease were more prone to recurrent HSV keratitis compared to mild cases (p < 0.001). These findings suggest that the timely appropriate treatment of atopic conjunctival disease may help reduce the frequency and severity of recurrent HSV keratitis and its complications.

Updates in Diagnostic Imaging for Infectious Keratitis: A Review

Infectious keratitis (IK) is among the top five leading causes of blindness globally. Early diagnosis is needed to guide appropriate therapy to avoid complications such as vision impairment and blindness. Slit lamp microscopy and culture of corneal scrapes are key to diagnosing IK. Slit lamp photography was transformed when digital cameras and smartphones were invented. The digital camera or smartphone camera sensor's resolution, the resolution of the slit lamp and the focal length of the smartphone camera system are key to a high-quality slit lamp image. Alternative diagnostic tools include imaging, such as optical coherence tomography (OCT) and in vivo confocal microscopy (IVCM). OCT's advantage is its ability to accurately determine the depth and extent of the corneal ulceration, infiltrates and haze, therefore characterizing the severity and progression of the infection. However, OCT is not a preferred choice in the diagnostic tool package for infectious keratitis. Rather, IVCM is a great aid in the diagnosis of fungal and Acanthamoeba keratitis with overall sensitivities of 66-74% and 80-100% and specificity of 78-100% and 84-100%, respectively. Recently, deep learning (DL) models have been shown to be promising aids for the diagnosis of IK via image recognition. Most of the studies that have developed DL models to diagnose the different types of IK have utilised slit lamp photographs. Some studies have used extremely efficient single convolutional neural network algorithms to train their models, and others used ensemble approaches with variable results. Limitations of DL models include the need for large image datasets to train the models, the difficulty in finding special features of the different types of IK, the imbalance of training models, the lack of image protocols and misclassification bias, which need to be overcome to apply these models into real-world settings. Newer artificial intelligence technology that generates synthetic data, such as generative adversarial networks, may assist in overcoming some of these limitations of CNN models.

Role of IL-27 in HSV-1-Induced Herpetic Stromal Keratitis

Herpetic stromal keratitis (HSK) is a painful and vision-impairing disease caused by recurrent HSV-1 infection of the cornea. The virus replication in the corneal epithelium and associated inflammation play a dominant role in HSK progression. Current HSK treatments targeting inflammation or virus replication are partially effective and promote HSV-1 latency, and long-term use can cause side effects. Thus, understanding molecular and cellular events that control HSV-1 replication and inflammation is crucial for developing novel HSK therapies. In this study, we report that ocular HSV-1 infection induces the expression of IL-27, a pleiotropic immunoregulatory cytokine. Our data indicate that HSV-1 infection stimulates IL-27 production by macrophages. Using a primary corneal HSV-1 infection mouse model and IL-27 receptor knockout mice, we show that IL-27 plays a critical role in controlling HSV-1 shedding from the cornea, the optimum induction of effector CD4+ T cell responses, and limiting HSK progression. Using in vitro bone marrow-derived macrophages, we show that IL-27 plays an antiviral role by regulating macrophage-mediated HSV-1 killing, IFN-β production, and IFN-stimulated gene expression after HSV-1 infection. Furthermore, we report that IL-27 is critical for macrophage survival, Ag uptake, and the expression of costimulatory molecules involved in the optimum induction of effector T cell responses. Our results indicate that IL-27 promotes endogenous antiviral and anti-inflammatory responses and represents a promising target for suppressing HSK progression.

UV-B induced HSV-1 reactivation leads to infectious virus in the corneas of virtually all latently infected mice and requires an intact STING to develop herpetic stromal keratitis

Reactivation of latent herpes simplex type 1 results in virus returning to the cornea leading to recurrent herpetic stromal keratitis (rHSK). We compare two competing models to reactivate viruses from latency, UV-B irradiation and cyclophosphamide. Results revealed that while both result in corneal recrudescence, only UV-B irradiation results in rHSK. To better understand the dynamics of reactivation, we analyzed corneas for both the presence of infectious viruses and the dynamics of exposure to multiple reactivations using UV-B. We noted that multiple reactivations result in progressively worse corneal disease. We also noted that expression of IFNα and STING, surragate markers for the presence of virus, are induced by the presence of reactivated virus. Studies to determine the importance of STING to the development of HSK revealed that in the absence of STING, mice do not develop significant HSK and the magnitude of the infiltrate of CD45 + cells in these corneas is significantly reduced. The resulting paucity of CD45 + CD11b + GR-1 + F4/80-neutrophils, and to a lesser extent CD45 + CD11b + GR-1-F4/80 + macrophages in B6-STING KO mice following reactivation is likely the underlying cause for lack of rHSK as has been noted by ourselves and others. These results underscore the critical importance of STING's role in developing rHSK.

Atypical Presentation of Herpes Stromal Keratitis in a Contact Lens Wearer

This article describes the case of a 21-year-old female habitual contact lens wearer who complained of left eye pain, redness, and decreased vision for one week. When a ring-shaped corneal infiltration indicative of an Acanthamoeba infection was discovered, standard anti-amoebic topical therapy with polyhexamethylene biguanide and chlorhexidine was commenced. However, her keratitis worsened. At the same time, corneal scraping revealed no pathogens. An anterior chamber examination revealed a loss of corneal sensation, and a positive herpes simplex virus (HSV) immunoglobulin G serology test indicated HSV keratitis. She was eventually treated with oral anti-viral medication and recovered completely. Her case was unusual, as she had a history of contact lens use, painful corneal ulceration, and the development of Acanthamoeba keratitis-like corneal ring infiltration. This case also reinforces the various manifestations of HSV keratitis, which lead to delayed diagnosis and treatment.

Pathophysiology of reinfection by exogenous HSV-1 is driven by heparanase dysfunction

Limited knowledge exists on exogenous DNA virus reinfections. Herpes simplex virus-1 (HSV-1), a prototype DNA virus, causes multiple human diseases including vision-threatening eye infections. While reinfection with an exogenous HSV-1 strain is considered plausible, little is known about the underlying mechanisms governing its pathophysiology in a host. Heparanase (HPSE), a host endoglycosidase, when up-regulated by HSV-1 infection dictates local inflammatory response by destabilizing tissue architecture. Here, we demonstrate that HSV-1 reinfection in mice causes notable pathophysiology in wild-type controls compared to the animals lacking HPSE. The endoglycosidase promotes infected cell survival and supports a pro-disease environment. In contrast, lack of HPSE strengthens intrinsic immunity by promoting cytokine expression, inducing necroptosis of infected cells, and decreasing leukocyte infiltration into the cornea. Collectively, we report that immunity from a recent prior infection fails to abolish disease manifestation during HSV-1 reinfection unless HPSE is rendered inactive.

Acrophialophora: A Comprehensive Review of Clinical Guidelines and Diagnosis

Acrophialophora is a saprotrophic genus of fungi found in both temperate and tropical regions. The genus is comprised of 16 species, with the subspecies A. fusispora and A. levis necessitating the most clinical concern. Acrophialophora is an opportunistic pathogen with a broad range of clinical manifestations; the fungus has been implicated in cases of fungal keratitis, lung infection, and brain abscess. Acrophialophora infection is particularly of concern for immunocompromised patients, who often present with a more severe disease course involving disseminated infection and may not exhibit typical symptoms. Early diagnosis and therapeutic intervention are critical to the successful clinical management of Acrophialophora infection. Guidelines for antifungal treatment have yet to be established, partially due to the lack of documented cases. Aggressive use of antifungal agents and long-term treatment is required, especially in immunocompromised patients and patients with systemic involvement, due to the potential for morbidity and mortality. In addition to outlining the rarity and epidemiology of the disease, this review provides an overview of the diagnosis and clinical management of Acrophialophora infection to facilitate an early diagnosis and appropriate interventions.

Role of Innate Interferon Responses at the Ocular Surface in Herpes Simplex Virus-1-Induced Herpetic Stromal Keratitis

Herpes simplex virus type 1 (HSV-1) is a highly successful pathogen that primarily infects epithelial cells of the orofacial mucosa. After initial lytic replication, HSV-1 enters sensory neurons and undergoes lifelong latency in the trigeminal ganglion (TG). Reactivation from latency occurs throughout the host's life and is more common in people with a compromised immune system. HSV-1 causes various diseases depending on the site of lytic HSV-1 replication. These include herpes labialis, herpetic stromal keratitis (HSK), meningitis, and herpes simplex encephalitis (HSE). HSK is an immunopathological condition and is usually the consequence of HSV-1 reactivation, anterograde transport to the corneal surface, lytic replication in the epithelial cells, and activation of the host's innate and adaptive immune responses in the cornea. HSV-1 is recognized by cell surface, endosomal, and cytoplasmic pattern recognition receptors (PRRs) and activates innate immune responses that include interferons (IFNs), chemokine and cytokine production, as well as the recruitment of inflammatory cells to the site of replication. In the cornea, HSV-1 replication promotes type I (IFN-α/β) and type III (IFN-λ) IFN production. This review summarizes our current understanding of HSV-1 recognition by PRRs and innate IFN-mediated antiviral immunity during HSV-1 infection of the cornea. We also discuss the immunopathogenesis of HSK, current HSK therapeutics and challenges, proposed experimental approaches, and benefits of promoting local IFN-λ responses.

Tear Film MicroRNAs as Potential Biomarkers: A Review

MicroRNAs are non-coding RNAs that serve as regulatory molecules in a variety of pathways such as inflammation, metabolism, homeostasis, cell machinery, and development. With the progression of sequencing methods and modern bioinformatics tools, novel roles of microRNAs in regulatory mechanisms and pathophysiological states continue to expand. Advances in detection methods have further enabled larger adoption of studies utilizing minimal sample volumes, allowing the analysis of microRNAs in low-volume biofluids, such as the aqueous humor and tear fluid. The reported abundance of extracellular microRNAs in these biofluids has prompted studies to explore their biomarker potential. This review compiles the current literature reporting microRNAs in human tear fluid and their association with ocular diseases including dry eye disease, Sjögren's syndrome, keratitis, vernal keratoconjunctivitis, glaucoma, diabetic macular edema, and diabetic retinopathy, as well as non-ocular diseases, including Alzheimer's and breast cancer. We also summarize the known roles of these microRNAs and shed light on the future progression of this field.

Impact of the use of anti-glaucoma medications on the risk of herpetic keratitis recurrence

PURPOSE

Numerous case reports have associated anti-glaucoma medications with recurrence of herpes simplex virus (HSV) and herpes zoster virus (HZV) keratitis. The aim of our study was to determine whether different anti-glaucoma agents are associated with recurrence of herpetic keratitis.

METHODS

This was a retrospective cohort study using health databases from a Canadian province from January 2001 to December 2012. A new cohort of users on topical prostaglandins (PGs), beta blockers (BBs), alpha-2 agonists (AAs) and carbonic anhydrase inhibitors (CAIs) was created. The date of the third anti-glaucoma drug dispensation within 90 days was deemed the index date of the case. Herpetic keratitis events, as defined by an ICD-9/10 code for HSV or HZV keratitis, or the dispensation of an anti-viral medication by either an ophthalmologist or an optometrist, were examined prior to and following the index date. Risk ratios (RRs) were computed to compare the risk of HSV/HZV keratitis among the PG, BB, AA, and CAI groups individually and collectively while adjusting for age and sex.

RESULTS

Among 19,986 users of glaucoma medications identified, there were 684 cases of HSV/HZV keratitis. There was no increased risk of HSV/HZV keratitis recurrence for any of the four glaucoma medications classes individually or collectively when adjusted for age and sex. There was also no increased risk for redeveloping either HSV keratitis only or HZV keratitis only amongst all anti-glaucoma users.

CONCLUSION

There is no association between the use of topical ocular hypotensive therapies and HSV/HZV keratitis recurrence. Further studies are needed to confirm these findings.

Clinical Management of Herpes Simplex Virus Keratitis

Herpes simplex virus (HSV) keratitis is one of the leading causes of blindness worldwide. Additionally, up to 90% of the population in some countries is seropositive for HSV. HSV can cause a wide spectrum of ocular disease ranging from blepharitis to retinitis. Although the initial clinical expressions of HSV-1 and HSV-2 are similar, HSV-2 has been reported more frequently in association with recurrent HSV disease. Besides irreversible vision loss from keratitis, HSV also causes encephalitis and genital forms of the disease. Despite these statistics, there remains no vaccine against HSV. Current treatment therapies for related ocular diseases include the use of oral and topical antivirals and topical corticosteroids. While effective in many cases, they fail to address the latency and elimination of the virus, making it ineffective in addressing recurrences, a factor which increases the risk of vision loss. As such, there is a need for continued research of other potential therapeutic targets. This review utilized several published articles regarding the manifestations of HSV keratitis, antiviral immune responses to HSV infection, and clinical management of HSV keratitis. This review will summarize the current knowledge on the host–virus interaction in HSV infections, as well as highlighting the current and potential antiviral therapeutics.

Advances in the diagnosis of herpes simplex stromal necrotising keratitis: A feasibility study on deep learning approach

Purpose

Infectious keratitis, especially viral keratitis (VK), in resource-limited settings, can be a challenge to diagnose and carries a high risk of misdiagnosis contributing to significant ocular morbidity.

We aimed to

employ and study the application of artificial intelligence-based deep learning (DL) algorithms to diagnose VK.

Methods

A single-center retrospective study was conducted in a tertiary care center from January 2017 to December 2019 employing DL algorithm to diagnose VK from slit-lamp (SL) photographs. Three hundred and seven diffusely illuminated SL photographs from 285 eyes with polymerase chain reaction-proven herpes simplex viral stromal necrotizing keratitis (HSVNK) and culture-proven nonviral keratitis (NVK) were included. Patients having only HSV epithelial dendrites, endothelitis, mixed infection, and those with no SL photographs were excluded. DenseNet is a convolutional neural network, and the two main image datasets were divided into two subsets, one for training and the other for testing the algorithm. The performance of DenseNet was also compared with ResNet and Inception. Sensitivity, specificity, receiver operating characteristic (ROC) curve, and the area under the curve (AUC) were calculated.

Results

The accuracy of DenseNet on the test dataset was 72%, and it performed better than ResNet and Inception in the given task. The AUC for HSVNK was 0.73 with a sensitivity of 69.6% and specificity of 76.5%. The results were also validated using gradient-weighted class activation mapping (Grad-CAM), which successfully visualized the regions of input, which are significant for accurate predictions from these DL-based models.

Conclusion

DL algorithm can be a positive aid to diagnose VK, especially in primary care centers where appropriate laboratory facilities or expert manpower are not available.

Natural Formulations Based on Olea europaea L. Fruit Extract for the Topical Treatment of HSV-1 Infections

In the present study, a hydroxytyrosol-rich Olea europaea L. fruit extract (OFE) was added to three thoroughly green formulations—hydrogel, oleogel, and cream—in order to evaluate their antiviral activity against HSV-1. The extract was characterized by different analytical techniques, i.e., FT-IR, XPS, and TGA. HPLC analyses were carried out to monitor the content and release of hydroxytyrosol in the prepared formulations. The total polyphenol content and antioxidant activity were investigated through Folin–Ciocâlteu’s reagent, DPPH, and ABTS assays. The ability of the three formulations to convey active principles to the skin was evaluated using a Franz cell, showing that the number of permeated polyphenols in the hydrogel (272.1 ± 1.8 GAE/g) was significantly higher than those in the oleogel and cream (174 ± 10 and 179.6 ± 2 GAE/g, respectively), even if a negligible amount of hydroxytyrosol crossed the membrane for all the formulations. The cell viability assay indicated that the OFE and the three formulations were not toxic to cultured Vero cells. The antiviral activity tests highlighted that the OFE had a strong inhibitory effect against HSV-1 with a 50% inhibitory concentration (IC50) at 25 µg/mL, interfering directly with the viral particles. Among the three formulations, the hydrogel exhibited the highest antiviral activity also against the acyclovir-resistant strain.

Infectious keratitis: A review

Globally, infectious keratitis is the fifth leading cause of blindness. The main predisposing factors include contact lens wear, ocular injury and ocular surface disease. Staphylococcus species, Pseudomonas aeruginosa, Fusarium species, Candida species and Acanthamoeba species are the most common causal organisms. Culture of corneal scrapes is the preferred initial test to identify the culprit organism. Polymerase chain reaction (PCR) tests and in vivo confocal microscopy can complement the diagnosis. Empiric therapy is typically commenced with fluoroquinolones, or fortified antibiotics for bacterial keratitis; topical natamycin for fungal keratitis; and polyhexamethylene biguanide or chlorhexidine for acanthamoeba keratitis. Herpes simplex keratitis is mainly diagnosed clinically; however, PCR can also be used to confirm the initial diagnosis and in atypical cases. Antivirals and topical corticosteroids are indicated depending on the corneal layer infected. Vision impairment, blindness and even loss of the eye can occur with a delay in diagnosis and inappropriate antimicrobial therapy.

Incidence and Risk Factors of Bilateral Herpetic Keratitis: 2022 Update

Simultaneously occurring bilateral herpetic keratitis is a rare clinical manifestation of ocular herpes. Immunocompromised patients are more susceptible to develop bilateral disease. The purpose of this study is to review recent literature on the topic and to highlight latest updates, regarding risk factors and possible correlations to the disease, as well as new therapeutic options.

CD137 costimulation is associated with reduced herpetic stromal keratitis and with developing normal CD8+ T cells in trigeminal ganglia

Costimulatory interactions can be critical in developing immune responses to infectious agents. We recently reported that herpes simplex type 1 (HSV-1) infections of the cornea require a functional CD28-CD80/86 interaction to not only reduce the likelihood of encephalitis, but also to mediate herpetic stromal keratitis (HSK) following viral reactivation. In this same spirit we decided to determine the role that CD137 costimulation plays during HSK. Using both B6-CD137L^-/- mice, as well as antagonistic and agonistic antibodies to CD137 we characterize the immune response and to what extent CD137 plays an important role during this disease. Immune responses were measured in both the cornea and in the trigeminal ganglia where the virus forms a latent infection. We demonstrate that CD137 costimulation leads to reduced corneal disease. Interestingly, we observed that lack of CD137 costimulation resulted in significantly reduced CD8⁺ T expansion and function in the trigeminal ganglia. Finally, we showed that viruses that have been genetically altered to express CD137 display significantly reduced corneal disease, though they did present similar levels of trigeminal infection and peripheral virus production following reactivation of a latent infection. CD137 interactions lead to reduced HSK and are necessary to develop robust trigeminal CD8⁺ T cell responses.

A proof-of-concept study for the efficacy of dispirotripiperazine PDSTP in a rabbit model of herpes simplex epithelial keratitis

Herpes simplex keratitis is an important infectious cause of blindness worldwide. The mainstay of antiviral therapy is treatment with long-established nucleoside analogues orally or topically. However, the emergence of resistant strains may become a major health concern in the future. Therefore, the development of backup antiherpetic medicines is urgently needed. Small molecule PDSTP is known to be active against herpes simplex type 1 strains in vitro, affecting early host-pathogen interactions. Here, we evaluated its preclinical efficacy in a rabbit model of herpes simplex epithelial keratitis. The mean course of keratitis and the corneal lesions in the 1.0% PDSTP gel group was statistically significantly less than in the negative control group and was comparable to that in the aciclovir group. These findings open up new opportunities for the development of antiherpetic drugs with an original mechanism of action.

Corneal Nodules and Possible Pathologies: A Case Series

Corneal nodular lesions are not uncommon in clinical practice. Diagnosing and managing this condition can be challenging due to its variable causes. This article highlights three cases of corneal nodular lesions. A common clinical pathway for the diagnosis and treatment of cornea nodular lesions is discussed. Two young females and an elderly man presented with a unilateral corneal nodule of variable duration, which was further demonstrated on anterior segment optical coherence tomography (AS-OCT). Several diagnoses were made after thorough history and examination which include herpetic stromal keratitis, phlyctenular keratoconjunctivitis secondary to blepharitis, and Salzmann nodular degeneration. All cases were initiated on topical antibiotics and topical steroids with additional medication or surgical procedure onboard according to their clinical condition. The corneal nodules resolved with scarring after a period of treatment. In conclusion, corneal nodular lesions can be associated with various pathologies. Thorough history, examination, and appropriate investigations are needed to reveal the underlying causes. Serial anterior segment images and AS-OCT are useful to monitor progression and treatment response. Prompt diagnosis and initiation of treatment are crucial to prevent further complications.

Microsporidia-induced stromal keratitis: a new cause of presumed immune stromal (interstitial) keratitis

BACKGROUND AND OBJECTIVE

To describe the clinical features, diagnosis and management of immune stromal keratitis/interstitial keratitis (IK) associated with microsporidial epithelial keratitis.

METHODS

Between October 2020 and January 2021, medical records of IK patients microbiologically proven as microsporidia from samples collected from corneal epithelium on smear examination, and/ or molecular analysis were reviewed. Demography, clinical profile and treatment were analysed. Real-time PCR (RT-PCR) for adenovirus (ADV), Epstein-Barr virus (EBV), herpes simplex virus (HSV) and varicella-zoster virus (VZV) was done.

RESULTS

Twenty of 152 (13%) microbiologically proven cases of microsporidial keratitis were diagnosed as IK during the study period, the mean age and duration of symptoms were 35.7±11.4 years and 46.3±27.7 days, respectively. Half had predisposing risk factors, like trauma; and 30% had prior recurrences. One-fourth of patients were using antivirals on presentation. Characteristic presentations included disciform keratitis(n=12), incomplete/complete ring(n=5), and combination(n=3), along with variable subepithelial infiltrates (n=14). All cases had stromal oedema, with an intact epithelium and fine pigment dusting on endothelium. Corneal epithelial scrapings had scanty microsporidia spores in smears of 17/20 (85%), and pan-microsporidial DNA was identified in 14/20 (70%), with Vittaforma corneae by sequencing in 11/20 (55%). Other viruses detected were ADV (14,70%), VZV (2,10%), EBV (1,5%) and HSV (1,5%). Rapid resolution of inflammation and oedema within 2 weeks of starting steroids was seen in all cases.

CONCLUSION

Microsporidia epithelial keratitis induced stromal inflammatory keratitis; is distinguished from microsporidial keratoconjunctivitis and stromal keratitis, by characteristic clinical features, and response to topical steroids.

Comprehensive Compositional Analysis of the Slit Lamp Bacteriota

Slit lamps are routinely used to examine large numbers of patients every day due to high throughput. Previous, cultivation-based results suggested slit lamps to be contaminated with bacteria, mostly coagulase-negative staphylococci, followed by micrococci, bacilli, but also Staphylococcus aureus. Our study aimed at obtaining a much more comprehensive, cultivation-independent view of the slit lamp bacteriota and its hygienic relevance, as regularly touched surfaces usually represent fomites, particularly if used by different persons. We performed extensive 16S rRNA gene sequencing to analyse the bacteriota, of 46 slit lamps from two tertiary care centers at two sampling sites, respectively. 82 samples yielded enough sequences for downstream analyses and revealed contamination with bacteria of mostly human skin, mucosa and probably eye origin, predominantly cutibacteria, staphylococci and corynebacteria. The taxonomic assignment of 3369 ASVs (amplicon sequence variants) revealed 19 bacterial phyla and 468 genera across all samples. As antibiotic resistances are of major concern, we screened all samples for methicillin-resistant Staphylococcus aureus (MRSA) using qPCR, however, no signals above the detection limit were detected. Our study provides first comprehensive insight into the slit lamp microbiota. It underlines that slit lamps carry a highly diverse, skin-like bacterial microbiota and that thorough cleaning and disinfection after use is highly recommendable to prevent eye and skin infections.

INCIDENCE OF HERPES SIMPLEX VIRUS KERATITIS AND OTHER OCULAR DISEASE: GLOBAL REVIEW AND ESTIMATES

Purpose: We aimed to review available data on the incidence of herpes simplex virus (HSV) keratitis and other HSV ocular disease and to estimate the global burden of HSV ocular disease. Methods: We searched Medline and Embase databases to October 2020 for studies reporting on the incidence of HSV ocular disease. Study quality was evaluated using a four-point checklist. Pooled estimates were applied to 2016 population data to estimate global HSV ocular disease burden. Numbers with uniocular vision impairment (any visual acuity <6/12) were estimated by applying published risks to case numbers. Results: Fourteen studies had incidence data; seven met our quality criteria. In 2016, an estimated 1.7 (95% confidence interval, 95% CI 1.0–3.0) million people had HSV keratitis, based on a pooled incidence of 24.0 (95% CI 14.0–41.0; N = 2; I² = 97.7%) per 100,000 person-years. The majority had epithelial keratitis (pooled incidence 16.1 per 100,000; 95% CI 11.6–22.3; N = 3; I² = 92.6%). Available studies were few and limited to the USA and Europe. Data were even more limited for HSV uveitis and retinitis, although these conditions may collectively contribute a further >0.1 million cases. Based on global incidence, some 230,000 people may have newly acquired uniocular vision impairment associated with HSV keratitis in 2016. Conclusion: Over 1.8 million people may have herpetic eye disease annually. Preventing HSV infection could therefore have an important impact on eye health. Herpetic eye disease burden is likely to have been underestimated, as many settings outside of the USA and Europe have higher HSV-1 prevalence and poorer access to treatment.

Advancing Our Understanding of Corneal Herpes Simplex Virus-1 Immune Evasion Mechanisms and Future Therapeutics

Herpes stromal keratitis (HSK) is a disease that commonly affects the cornea and external eye and is caused by Herpes Simplex Virus type 1 (HSV-1). This virus infects approximately 66% of people worldwide; however, only a small portion of these people will develop symptoms in their lifetime. There is no cure or vaccine available for HSV-1; however, there are treatments available that aim to control the inflammation caused by the virus and prevent its recurrence. While these treatments are beneficial to those suffering with HSK, there is a need for more effective treatments to minimise the need for topical steroids, which can have harmful effects, and to prevent bouts of disease reactivation, which can lead to progressive corneal scarring and visual impairment. This review details the current understanding of HSV-1 infection and discusses potential novel treatment options including microRNAs, TLRs, mAbs, and aptamers.

IFN-λ Regulates Neutrophil Biology to Suppress Inflammation in Herpes Simplex Virus-1-Induced Corneal Immunopathology

HSV-1 infection of the cornea causes a severe immunoinflammatory and vision-impairing condition called herpetic stromal keratitis (SK). The virus replication in corneal epithelium followed by neutrophil- and CD4⁺ T cell-mediated inflammation plays a dominant role in SK. Although previous studies demonstrate critical functions of type I IFNs (IFN-α/β) in HSV-1 infection, the role of recently discovered IFN-λ (type III IFN), specifically at the corneal mucosa, is poorly defined. Our study using a mouse model of SK pathogenesis shows that HSV-1 infection induces a robust IFN-λ response compared with type I IFN production at the corneal mucosal surface. However, the normal progression of SK indicates that the endogenous IFN responses are insufficient to suppress HSV-1-induced corneal pathology. Therefore, we examined the therapeutic efficacy of exogenous rIFN-λ during SK progression. Our results show that rIFN-λ therapy suppressed inflammatory cell infiltration in the cornea and significantly reduced the SK pathologic condition. Early rIFN-λ treatment significantly reduced neutrophil and macrophage infiltration, and IL-6, IL-1β, and CXCL-1 production in the cornea. Notably, the virucidal capacity of neutrophils and macrophages measured by reactive oxygen species generation was not affected. Similarly, ex vivo rIFN-λ treatment of HSV-1-stimulated bone marrow-derived neutrophils significantly promoted IFN-stimulated genes without affecting reactive oxygen species production. Collectively, our data demonstrate that exogenous topical rIFN-λ treatment during the development and progression of SK could represent a novel therapeutic approach to control HSV-1-induced inflammation and associated vision impairment.

Bowman Layer Onlay Transplantation to Manage Herpes Corneal Scar

PURPOSE

To introduce the concept of using a Bowman layer (BL) onlay graft to manage superficial herpetic corneal scarring and to describe the clinical outcomes of the first 2 cases undergoing this procedure.

METHODS

Two patients with a quiescent superficial corneal scar after herpes (varicella zoster virus [n = 1] and herpes simplex virus [n = 1]) keratitis underwent BL onlay transplantation. After the removal of the host epithelium and limited superficial keratectomy, an isolated BL graft was placed onto the host corneal surface. The cornea was then covered with an amniotic membrane and a bandage contact lens. Best spectacle-corrected visual acuity (VA) and/or best contact lens-corrected VA (BCLVA), biomicroscopy, corneal tomography, and anterior segment optical coherence tomography were recorded at 1 week, 1 month, and 3, 6, 9, 12, and 18 months postoperatively.

RESULTS

In both cases, the surgical and postoperative courses were uneventful. An improvement of the corneal clarity was observed at biomicroscopy, and no varicella zoster virus/herpes simplex virus reactivation occurred throughout the follow-up period. Biomicroscopy, Scheimpflug imaging, and anterior segment optical coherence tomography showed a completely epithelialized and well-integrated graft postoperatively. In case 1, BCLVA with a scleral lens improved from 20/100 (0.1) preoperatively to 20/32 (0.6) postoperatively. For case 2, no preoperative BCLVA was available, but a BCLVA of 20/36 (0.55) was achieved after the procedure.

CONCLUSIONS

A BL onlay graft may be a feasible surgical procedure, which may have the potential to reduce superficial corneal scarring and/or anterior corneal irregularities without resorting to deeper keratoplasty in these complex cases.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

Applications of Nanoparticles for Herpes Simplex Virus (HSV) and Human Immunodeficiency Virus (HIV) Treatment

In recent years, the growing studies focused on the immunotherapy of hepatocellular carcinoma and proved the preclinical and clinical promises of host antitumor immune response. However, there were still various obstacles in meeting satisfactory clinic need, such as low response rate, primary resistance and secondary resistance to immunotherapy. Tackling these barriers required a deeper understanding of immune underpinnings and a broader understanding of advanced technology. This review described immune microenvironment of liver and HCC which naturally decided the complexity of immunotherapy, and summarized recent immunotherapy focusing on different points. The ever-growing clues indicated that the instant killing of tumor cell and the subsequent relive of immunosuppressive microenvironment were both indis- pensables. The nanotechnology applied in immunotherapy and the combination with intervention technology was also discussed.

Quantitative real-time polymerase chain reaction analysis in herpes simplex virus keratitis with and without epithelial involvement

PURPOSE

To evaluate the quantitative real-time polymerase chain reaction (qRT-PCR) analysis in herpes simplex virus (HSV) keratitis with and without epithelial involvement.

METHODS

This cross-sectional study was performed on 70 patients with different HSV types and an active ocular lesion in Farabi Eye Hospital, Tehran, Iran. From these 70 patients, 171 samples were collected, including seventy tear samples and 33 scraping samples from involved eyes; and 68 samples from uninvolved fellow eyes. Samples were frozen at - 70 °C until DNA extraction was performed. Quantity of HSV was measured using qRT-PCR in all three samples.

RESULTS

The mean age of HSV patients was 52.19 ± 20.42 years (range, 4-85 years). Forty-one (58.6%) HSV patients had epithelial involvement, and 29 (41.4%) patients did not have epithelial involvement. In PCR-positive cases, the mean number of viruses in affected eyes' tears (8,831,234 ± 4,051,979) was significantly higher than uninvolved eyes' tears (182,603 ± 69,141) (P = 0.02). The mean of PCR in HSV patients with and without epithelial involvement was 10,320,269 ± 5,329,800 and 1,469,419 ± 1,070,396, respectively (P = 0.04). The qRT-PCR of involved tears in both groups (with and without epithelial involvement) was significantly higher than unaffected eyes' tears (P < 0.0001 and P = 0.01, respectively). In cases with and without epithelial involvement, the cutoff points of viral load in involved eyes' tears were 281,000 and 126,000 copies, respectively.

CONCLUSION

The results indicated that qRT-PCR is an excellent method for the detection of herpes simplex keratitis.

20 years since the Herpetic Eye Disease Study: Lessons, developments and applications to clinical practice

Herpes Simplex Virus (HSV) is the most common virus that causes eye disease. Although around 60% of the world's population are seropositive for HSV antigens, fortunately, it is estimated that only 1% of seropositive individuals develop eye disease. The most common ocular manifestation of HSV is keratitis, while uveitis and retinal necrosis occur in a small number of cases. HSV keratitis is a debilitating disease, for several reasons: pain , photophobia, and vision loss in acute disease, latency of the virus which leads to infection reactivation from various triggers, scarring, and neovascularisation, leading to permanent vision loss with poor visual rehabilitation prospects. The Herpetic Eye Disease Study (HEDS) was a landmark series of randomised controlled trials in the 1990s that set the benchmark for evidence-based treatment guidelines for anterior eye herpetic disease. Since this time, there has been a change in the distribution of seroprevalence of herpes in the community, a simplified diagnostic classification, advances in treatment options, an emergence of new and a better understanding of risk factors, and discoveries in science that show promise for vaccine and novel future treatments. However, many of the principles of the HEDS study remain rightly entrenched in clinical practice. In this article, the HEDS study is revisited 20 years on through the lens of published literature, to determine current best practise and look towards the future.

The Role of Tissue Resident Memory CD4 T Cells in Herpes Simplex Viral and HIV Infection

Tissue-resident memory T cells (TRM) were first described in 2009. While initially the major focus was on CD8+ TRM, there has recently been increased interest in defining the phenotype and the role of CD4+ TRM in diseases. Circulating CD4+ T cells seed CD4+ TRM, but there also appears to be an equilibrium between CD4+ TRM and blood CD4+ T cells. CD4+ TRM are more mobile than CD8+ TRM, usually localized deeper within the dermis/lamina propria and yet may exhibit synergy with CD8+ TRM in disease control. This has been demonstrated in herpes simplex infections in mice. In human recurrent herpes infections, both CD4+ and CD8+ TRM persisting between lesions may control asymptomatic shedding through interferon-gamma secretion, although this has been more clearly shown for CD8+ T cells. The exact role of the CD4+/CD8+ TRM axis in the trigeminal ganglia and/or cornea in controlling recurrent herpetic keratitis is unknown. In HIV, CD4+ TRM have now been shown to be a major target for productive and latent infection in the cervix. In HSV and HIV co-infections, CD4+ TRM persisting in the dermis support HIV replication. Further understanding of the role of CD4+ TRM and their induction by vaccines may help control sexual transmission by both viruses.

Herpes Simplex Virus Keratitis in a University Tertiary Referral Centre - Clinical Features and Surgical Approaches

PURPOSE

To assess prevalence, clinical manifestations, required keratoplasties, follow-up, and outcome in patients with Herpes Simplex Virus Keratitis (HSK) attending a University Tertiary Referral Center.

DESIGN

Retrospective (12 years), descriptive, observational study.

METHODS

A total of 817 eyes with clinical diagnosis of HSK from 779 patients were classified by the type of presentation. We gathered data on the visual acuity, refraction, IOP, and required surgical procedures.

RESULTS

Stromal involvement including scars represented the most common diagnosis in our department and the main indication of penetrating keratoplasty (PKP). Epithelial keratitis (16%) presented with the best visual acuity at the first visit. Necrotizing keratitis represented 17% of the patients, 78% of whom required PKP; this group also had the worst visual acuity at first examination and was the main indication for emergency PKP. Among all eyes, 288 (35%) required PKP. A total of 230 (28%) PKPs were elective procedures and 58 (7%) PKPs were performed as emergency procedures. Two patients with quiet endothelial decompensations after recurrent HSV endotheliitis were treated with DMEK and had good visual outcomes without HSV recurrence at last follow-up.

CONCLUSIONS

HSK is a prevalent disease with severe consequences when not treated appropriately and on time. Even when making an accurate diagnosis, the disease can be extremely aggressive, with all the implications it brings to the patients and health system. Elective PKP had better outcomes in terms of visual acuity and clear graft percentage compared to emergency PKP.

Pathobiology and treatment of viral keratitis

Keratitis is one of the most prevalent ocular diseases manifested by partial or total loss of vision. Amongst infectious (viz., microbes including bacteria, fungi, amebae, and viruses) and non-infectious (viz., eye trauma, chemical exposure, and ultraviolet exposure, contact lens) risk factors, viral keratitis has been demonstrated as one of the leading causes of corneal opacity. While many viruses have been shown to cause keratitis (such as rhabdoviruses, coxsackieviruses, etc.), herpesviruses are the predominant etiologic agent of viral keratitis. This chapter will summarize current knowledge on the prevalence, diagnosis, and pathobiology of viral keratitis. Virus-mediated immunomodulation of host innate and adaptive immune components is critical for viral persistence, and dysfunctional immune responses may cause destruction of ocular tissues leading to keratitis. Immunosuppressed or immunocompromised individuals may display recurring disease with pronounced severity. Early diagnosis of viral keratitis is beneficial for disease management and response to treatment. Finally, we have discussed current and emerging therapies to treat viral keratitis.

Potential Role and Significance of Ocular Demodicosis in Patients with Concomitant Refractory Herpetic Keratitis

Purpose

To evaluate the role of Demodex infestation of the eyelids in patients with recurrent herpetic keratitis.

Patients and Methods

This is a retrospective and noncomparative case series. Twenty-seven patients with ocular demodicosis and recurrent herpetic keratitis under conventional treatments were enrolled. Demographic data and clinical photographs were collected. Ocular demodicosis was confirmed by eyelash examination under a microscope. Eyelid scrub was initiated in these patients after proving Demodex infestation. Response after treatment was reviewed.

Results

Herpetic keratitis was characterized by epithelial defect, including dendritic lesions (seven eyes, 25.9%), geographic ulcer (three eyes, 11.1%), and neurotrophic ulcer (two eyes, 7.4%), associated with stromal involvement in 12 cases. Six cases with stromal reactivation, including disciform keratitis (two eyes, 7.4%), immune ring (three eyes, 11.1%), and ghost vessel (one eye, 3.7%), presented no epithelial defect. Active anterior uveitis with keratic precipitates was found in 15 cases. Demodex blepharitis was diagnosed with cylindrical dandruff along their lashes in all patients. Other ocular findings include meibomian gland dysfunction (15 eyes, 55.6%), mal-aligned lashes (eight eyes, 29.6%), telangiectasia (14 eyes, 51.9%), conjunctivitis (18 eyes, 66.7%), and ocular rosacea (three eyes, 11.1%). Initial unstable clinical presentations showed deterioration of corneal melting into descemetocele, corneal perforation, recalcitrant stromal infiltration/uveitis, and uncontrollable IOP, despite antiherpetic medication. After treatment of Demodex blepharitis, infestation was under control, followed by subjective improvement of ocular symptoms and a stable clinical outcome.

Conclusion

Ocular demodicosis should be considered in patients with unstable recurrent herpetic keratitis. A prompt diagnosis and appropriate treatment may curb the progression of herpetic corneal infection.