Evidence-based treatment of herpes simplex virus keratitis: a systematic review

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.

Herpes simplex virus keratitis: electronic medical records driven big data analytics report from a tertiary eye institute of South India

OBJECTIVE

To describe the demographics and clinical profile of Herpes Simplex Virus (HSV) Keratitis in patients presenting to a multi-tier ophthalmology hospital network in South India.

METHODS

We have reviewed the medical records of all patients having a clinical diagnosis of any form of HSV keratitis, seen between May 2012 and August 2020 across the L V Prasad Eye Institute network. All the further analyses of the groups were performed using the keywords used for making the diagnosis of HSV keratitis and the data were collected from the electronic medical record system.

RESULTS

There were a total of 8308 (N = 8897 eyes) patients. Male: female ratio was 5368 (64.61%):2940 (35.39%). Unilateral involvement was in 7719 (92.91%) patients. The most common age group affected was between the third to fifth decades of life with 1544 (18.58%). 3708 (1.68%) eyes had mild visual impairment (< 20/70) while the rest of them had moderate to severe visual impairment as observed mainly (p ≤ 0.01) in Necrotizing stromal keratitis. 7314 (82.21%) eyes had normal intraocular pressure (10-21 mm Hg) while raised most commonly in keratouveitis (P ≤ 0.01). Epithelial Keratitis, Immune Stromal Keratitis, Endotheliitis, Neurotrophic keratopathy and Keratouveitis were observed in 1875 (17.22%) eyes, 5430 (61.03%) eyes, in 129(1.45%) eyes, 1188 (13.35%) eyes, 148 (1.66%) eyes and 256 (2.88%) eyes respectively.

CONCLUSION

Based on our institute-based data, the most common type of HSV keratitis is Immune stromal keratitis followed by epithelial keratitis. Although not representative of the general population, this data provide useful insights related to HSV keratitis from India.

Treatment of ocular-involving monkeypox virus with topical trifluridine and oral tecovirimat in the 2022 monkeypox virus outbreak

Purpose

To report a case of ocular involving monkeypox infection in the United States during the 2022 outbreak, and to review the literature regarding its clinical manifestations and management known to date.

Observations

A 36-year-old man with well controlled HIV presented to the emergency department with anal pain, diffuse rash, right eye pain, and right eye redness after he tested positive for monkeypox one week prior. Ocular examination showed bilateral periorbital vesicular lesions, right eye conjunctival injection, and a single white plaque on his right medial bulbar conjunctiva. Macular, vesicular, and pustular lesions were noted throughout his body, including the genital and perianal region. His ocular and systemic symptoms completely resolved after treatment with a ten-day course of 1% trifluridine and moxifloxacin drops in both eyes, as well as two weeks of oral tecovirimat.

Conclusion and Importance

In July of 2022, monkeypox virus was declared a global health emergency by the World Health Organization; however, there are no standard guidelines for monkeypox treatment. Data on its clinical presentation and course, especially pertaining to ocular manifestations, is limited. We highlight the importance of recognizing ophthalmic manifestations of monkeypox virus and a possible therapeutic approach to help guide the management of these patients.

A Clinical Case of Viral Keratitis

Keratitis is a pathological condition involving inflammation of the cornea. It can be an infectious or non-infectious disease. The causative organisms of keratitis are categorized as bacteria, viruses, fungi, or parasites. The viruses responsible for causing keratitis are herpes simplex virus (HSV), varicella-zoster virus, and adenoviruses. The clinical features of this infection may range from pain and redness of the eye to scarring of the cornea or blindness. We present the case of a 71-year-old elderly female patient suffering from viral (HSV) keratitis. She was referred to the department of ophthalmology with complaints of diminution of vision and watering in the right eye associated with pain and redness for one month, which was progressive and gradual in onset. On local examination, the surface of the cornea was irregular in the right eye, with the presence of old keratitis precipitates. Viral infection is the second leading cause of keratitis and is very common in the western world. Because the transmission is due to droplets and fomites, strict measures must be taken to prevent transmission. If anyone comes in contact, prophylactic antiviral therapy can be administered. The prognosis is favorable if adequately treated. It can lead to blindness if not treated on time.

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.

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.

Regulation of herpes simplex virus type 1 latency-reactivation cycle and ocular disease by cellular signaling pathways

Following acute infection, herpes simplex virus type 1 (HSV-1) establishes life-long latency in sensory and other neurons. Recurrent ocular HSV-1 outbreaks are generally due to reactivation from latency. The HSV-1 latency-reactivation cycle is a complex virus-host relationship. The viral encoded latency-associated transcript (LAT) is abundantly expressed in latency and encodes several micro-RNAs and other small non-coding RNAs, which may regulate expression of key viral and cellular genes. Certain cellular signaling pathways, including Wnt/β-catenin and mTOR pathway, mediate certain aspect of the latency-reactivation cycle. Stress, via activation of the glucocorticoid receptor and other stress induced cellular transcription factors, are predicted to trigger reactivation from latency by stimulating viral gene expression and impairing immune responses and inflammation. These observations suggest stress and certain cellular signaling pathways play key roles in regulating the latency-reactivation cycle and recurrent ocular disease.

Adoption of Innovation in Herpes Simplex Virus Keratitis

Herpes simplex keratitis, caused primarily by human herpes simplex virus type 1 (HSV-1), remains the most common infectious cause of unilateral blindness and vision impairment in the industrialized world. Major advances in the care of HSV keratitis have been driven in large part by the landmark Herpetic Eye Disease Study randomized clinical trials, which were among the first in ophthalmology to reflect emerging trial conventions, including multicenter subject enrollment, double-masking, placebo controls, and a priori sample size determinations. The results of these trials now form much of the evidence basis for the management of this disease. However, management patterns in clinical practice often deviate from evidence-based care. These perceived quality gaps have given rise to the evolving field of implementation science, which is concerned with the methods of promoting the application of evidence-based medicine within routine care. To overcome variations in the quality and consistency of care for HSV keratitis, a range of clinical- and technology-based innovations are proposed. The most pressing needs include the following: a rational and tractable disease classification scheme that provides an immediate link between the anatomical localization of disease (corneal epithelial, stromal, or endothelial) and the appropriate treatment, and the actualization of an electronic medical record system capable of providing evidence-based treatment algorithms at relevant points of care. The latter would also input data to population-wide disease registries to identify implementation-rich targets for quality improvement, education, and research. These innovations may allow us to reduce the human and economic burdens of this highly morbid, and often blinding, disease.

Clinical outcomes of herpes simplex keratitis: Two-year experience from a quaternary eye care centre in Sydney, Australia

PURPOSE

To report anti-viral therapy and outcomes for patients with herpes simplex keratitis (HSK) in a quaternary centre in Sydney, Australia.

METHODS

A retrospective case review of patients who received anti-viral medications for any form of HSK was conducted. Cases were identified from pathology results, pharmacy records and hospital coding data from 2012 to 2013. Clinical details including initial anti-viral treatment and outcome were collated from the medical records. Outcome was determined from when initial anti-viral treatment was stopped or changed, and classified as either clinically resolved, partially resolved or worsened for therapeutic indication; or as either success or failure for prophylaxis.

RESULTS

Anti-viral therapy was given for therapeutic and prophylactic indications at presentation in 252 (85%) and 44 patients (15%), respectively. Topical aciclovir five times daily and valaciclovir in doses ranging from 500 mg to 1 g, one to three times daily were the preferred anti-viral therapies. One hundred and fourteen patients (n = 114/296, 38.5%) also received topical corticosteroids. An outcome was determined for 210/296 (71%) patients. For therapeutic indication, half of the patients (90/174) partially resolved within 8 days, with best outcomes achieved for endothelial HSK (8/11, 73%) and keratouveitis (21/36, 58%). Adverse events, observed in 20% (35/174) of patients, included corneal perforation (n = 8) and secondary bacterial keratitis (n = 6). Prophylaxis with antiviral therapy was successful in two-thirds of patients after 6 months.

CONCLUSIONS

Clinical and visual outcomes varied with the type of HSK and prescribed therapies. Diverse initial anti-viral therapies were identified; standardising them may improve outcomes.

Development, Implementation, and Evaluation of Treatment Guidelines for Herpes Simplex Keratitis in Sydney, Australia

PURPOSE

To develop and measure the uptake of a local guideline for herpes simplex keratitis (HSK) and to standardize initial antiviral therapy in Australia.

METHODS

The Registered Nurses' Association of Ontario Toolkit: "Implementation of Best Practice Guidelines" was used to develop, implement, and evaluate the guideline at Sydney Eye Hospital. An implementation team was established to reach consensus on antiviral therapy guidelines through review of available evidence, identifying stakeholders, facilitators and barriers, creating strategies for implementation, and developing a sustainability plan. An audit of all adult HSK cases during a 6-month postguideline implementation period was conducted, and the results were compared with a preimplementation audit. A web-based survey was created to assess clinician awareness, usage, and level of knowledge of the guideline.

RESULTS

Clinicians, pharmacists, and administrative staff were identified as stakeholders. Changing clinician's behavior was the major barrier to implementation. Implementation strategies included printed and online materials and lectures to clinicians. A postimplementation audit included 85 patients, and 95 clinicians received a web-based survey. The dose of the prescribed antiviral medication was in alignment with the local guideline in 80% (51/64) of the patients compared with 73% (163/223) before implementation (P = 0.331). Stromal HSK with ulceration and keratouveitis were excluded because there were no recommendations before implementation. Over 70% of clinicians (30/41) were aware of the guideline and accessed them through educational resources.

CONCLUSIONS

Guidelines for the management of HSK may improve standardization of initial antiviral therapy in HSK. In practice, most clinicians were aware of and adhered to the local guideline.

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.

Herpes simplex virus infections in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of HSV in the pre- and post-transplant period. A majority of transplant recipients are seropositive for HSV-1 or 2. Compared with immunocompetent persons, SOT recipients shed HSV more frequently, have more severe clinical manifestations, and are slower to respond to therapy. Most HSV infection is diagnosed on clinical grounds, but patients may present with atypical lesions and/or other clinical manifestations. Acquisition from the donor is rare. Polymerase chain reaction is the preferred diagnostic test unless culture is needed for resistance testing. For limited mucocutaneous lesions, oral therapy can be used; however, in severe, disseminated, visceral or CNS involvement, acyclovir doses of up to 10 mg/kg every 8 hours intravenously should be initiated. Acyclovir-resistant HSV is less common in SOT patients than in HSCT and can be treated with foscarnet, though other novel therapies are currently under investigation. HSV-specific prophylaxis should be considered for all HSV-1 and HSV-2-seropositive organ recipients who are not receiving antiviral medication for CMV prevention that has activity against HSV.

Effect of photodynamic therapy by 810 and 940 nm diode laser on Herpes Simplex Virus 1: An in vitro study

INTRODUCTION

Herpes simplex virus (HSV) is among the most common viruses in humans. HSV1 is often responsible for oral and perioral herpetic lesions. Photodynamic therapy (PDT) is a novel antimicrobial modality that involves the use of laser and a photosensitizer with a specific wavelength. This study aimed to assess and compare the effect of PDT with 810 and 940 nm diode laser and indocyanine green (ICG) photosensitizer on HSV1.

METHODS

In this in vitro study, HSV1 isolated from herpes labialis and there were 6 experimental groups.The irradiation parameters were the same for all groups. Number of remaining viruses per milliliter in each group was determined using real-time polymerase chain reaction (PCR) and statistically analyzed by ANOVA.

RESULTS

The virus count in all groups significantly decreased compared to the control group (P < 0.05) except in group ICG- without irradiation (P > 0.05). Comparison of groups 810- and 940- (use of each laser alone) with groups 810+ and 940+ (use of each laser plus ICG) revealed that reduction in virus count in groups 810+ and 940+ was significantly greater than that in groups 810- and 940-.

CONCLUSION

810 nm diode laser irradiation and ICG causes the greatest reduction in number of HSV1 compared to all the other groups. ICG without laser irradiation has not significant efficacy on reduction of virus count.

A stepping stone in treating dendritic keratitis

PURPOSE

To report the outcome of self-retained amniotic membrane after debridement in recurrent dendritic keratitis.

OBSERVATIONS

A 70-year-old female with a recurrent dendritic corneal ulcer received debridement followed by placement of self-retained amniotic membrane. Five days after treatment, the patient experienced a complete resolution of symptoms, marked reduction of inflammation, complete re-epithelialization of the cornea and improvement of visual acuity. The corneal surface remained stable for 18 months despite noncompliance in using antiviral therapy.

CONCLUSIONS AND IMPORTANCE

Self-retained amniotic membrane after debridement appears effective in treating dendritic keratitis. While early debridement is crucial to remove the infected corneal epithelium, amniotic membrane was shown to enhance the healing without scarring or recurrence. Besides the known anti-inflammatory and anti-scarring effects of the amniotic membrane, it may have a potential topical antiviral effect that warrants further investigation.

Practice patterns for herpes simplex keratitis: A survey of ophthalmologists in Gulf Coast countries

Purpose

Herpes simplex is a common cause of visual disability, and there are published evidence-based guidelines for therapy. This survey aims to determine the preferred practice patterns of ophthalmologists in Gulf Coast Countries regarding herpetic eye disease, as well as identify areas of controversy or barriers to acceptance of evidence-based protocols.

Methods

Anonymous web-based survey of ophthalmologists in Saudi Arabia, Bahrain, the United Arab Emirates, and Oman.

Results

There were 48 responses to the survey. For a first episode of epithelial dendritic keratitis, 28.2% reported “observation” rather than specific therapy. The majority of respondents utilize oral or topical antiviral for epithelial keratitis, with oral antiviral being the most popular (43.6%). The majority also included a corticosteroid with antiviral for stromal keratitis (83.9%) or iritis (70.3%). Over 90% prescribe a prophylactic antiviral after keratoplasty for herpetic eye disease, although the length of therapy ranged widely from <6 months to indefinite. The perceived risk of recurrent disease was ranked as the most important factor when considering antiviral prophylaxis, followed by risk of adverse effects. Topical cyclosporine was utilized “never or almost never” by 76.9% of respondents.

Conclusions

Most respondents report following evidence-based guidelines. There was less consensus in areas where there are remaining knowledge gaps, such as the length of antiviral prophylaxis after keratoplasty and the potential role for topical cyclosporine.

Red eye emergencies in primary care

Severe red eye conditions can be the result of intraocular inflammation, corneal insults or inflammation, and acute glaucoma. These pathologies require the knowledge and assessment tools of an ophthalmologist. This article will discuss red eye emergencies that the NP should promptly recognize and refer to ophthalmology.

Clinical efficacy of oral ganciclovir for prophylaxis and treatment of recurrent herpes simplex keratitis

Background:

Herpes simplex keratitis (HSK) caused by herpes simplex virus 1 (HSV-1), which has high recurrent rate and incidence of severe vision loss, is the leading cause of infectious blindness in the world. The aim was to explore the clinical efficacy of oral ganciclovir (GCV) in the prevention of recurrent HSK.

Methods:

A multicenter, prospective, randomized, single-blind, and controlled clinical trial was conducted from April 2010 to June 2013. One hundred seventy-three patients (173 eyes involved) who were diagnosed as recurrent HSK definitely, including stromal keratitis and corneal endotheliitis, were divided into three groups randomly: negative control (placebo) group was topically administered with 0.15% GCV ophthalmic gel, 4 times per day and 0.1% fluorometholone eye drops, 3 times per day until resolution of HSK; positive control acyclovir (ACV) group was topically adopted the same ophthalmic gel and eye drops and additionally received oral ACV 400 mg 5 times a day for 10 weeks and followed by 400 mg 2 times per day for 6 months; test GCV group was topically adopted the same treatment as negative control group and additionally received oral GCV 1000 mg 3 times per day for 8 weeks. The symptoms and signs were evaluated before and after the therapy 1^st week, 2^nd week and then followed up every 2 weeks until recovery. Furthermore, we followed up recurrence of HSK for every 3 months after recovery and then assessed the cure time, recurrent rate and adverse reactions.

Results:

One hundred and seventy-three patients were followed up 7–48 months (mean 32.1 ± 12.3 months), but 34 patients were failed to follow-up. The cure time was 12.1 ± 4.3, 11.9 ± 4.0 weeks in negative control (placebo) group and positive control ACV group respectively (P = 0.991), which was longer than that in test GCV group (8.6 ± 2.8 weeks) and there was a significant difference between test GCV group and negative control (placebo) group or positive control ACV group (P = 0.000). Furthermore, the recurrent rate was higher in negative control (placebo) group (47.3%) than that in positive control group ACV (26.7%) and test GCV group (17.2%), and there was a great significant difference among the three groups (P = 0.007), but there was no significant difference between positive control ACV group and test GCV group (P = 0.358). In addition, there was no obvious adverse reaction expect neutropenia (only one patient in test GCV group).

Conclusion:

Short-term oral GCV could cure recurrent HSK and endotheliitis, shorten the course, reduce recurrent rate of HSK and have confirmed safety.

A systematic review and meta-analysis to compare the efficacy of acyclovir 3% ophthalmic ointment to idoxuridine in curing herpetic keratitis by Day 7 of treatment

BACKGROUND

This objective of the review and analysis is to demonstrate that acyclovir (ACV) 3% ophthalmic ointment is superior to idoxuridine (IDU) in treating herpetic keratitis (HK) presenting as dendritic and geographic ulcer sub-types.

METHODS

DATA SOURCES

Publications in human subjects were identified by searching the Ovid MEDLINE database through April 2011, combining medical subject headings (MESH) "Keratitis, Herpetic/" AND "Acyclovir/" limiting by the key words "topical" OR "ointment" and also restricted to MESH "Administration, Topical/" OR "Ointments/". The results were cross checked with the references used in the Cochrane Database Syst Rev. 1:1-134, 2009 and GlaxoSmithKline clinical documents related to acyclovir.

STUDY SELECTION

Randomized, double-masked studies in subjects diagnosed with HK with head to head comparator arms of ACV ophthalmic ointment and topical IDU that had actual or calculable healing rates at Day seven.

DATA EXTRACTION

Data independently extracted from identified articles by two authors of this manuscript.

DATA SYNTHESIS

Data from seven randomized, controlled trials (RCT) evaluating 432 subjects that met inclusion criteria (214 were treated with ACV and 218 were treated with IDU) and had Day seven healing rates calculable. All sub-classified lesions were identified as either dendritic ulcers (n = 185) or geographic ulcers (n = 35). The Cochran-Mantel-Haenszel (CMH) method in Biometrics 10:417-51, 1954 and JNCI 22:719-48, 1959, controlling for study, was performed as the primary analysis using SAS v9. Homogeneity was assessed using Breslow-Day-Tarone (BDT) test in IARC 1:1-32, 1980 and Biometrika 72:91-5, 1985. The analysis was performed with outliers removed to assess their impact.

RESULTS

ACV showed statistically significant greater odds of healing HK at Day seven in all subjects (Odds Ratio 3.95, 95% CI2.60, 6.00, p < 0.0001), in dendritic ulcers (Odds Ratio 4.22, 95% CI: 2.14, 8.32; p < 0.0001) and geographic ulcers (Odds Ratio 5.31, 95% CI: 1.09, 25.93; p = 0.0244).

CONCLUSION

ACV 3% ophthalmic ointment is a valuable intervention for dendritic and geographic corneal ulcers. ACV and IDU were generally well tolerated in the studies reviewed.

Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Eye disease due to herpes simplex virus (HSV) commonly presents as epithelial keratitis which, though usually self-limiting, may persist or progress without treatment.

OBJECTIVES

To compare the relative effectiveness of antiviral agents, interferon, and corneal debridement in the treatment of HSV epithelial keratitis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 12), PubMed (January 1946 to 31 December 2014), EMBASE (January 1980 to 31 December 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to 31 December 2014), System for Information on Grey Literature in Europe (OpenGrey) (January 1995 to 31 December 2014), BIOSIS (January 1926 to 5 May 2014), Scopus (January 1966 to 31 December 2014), Japan Science and Technology Institute (J-Global) (January 1975 to 31 December 2014), China National Knowledge Infrastructure (CNKI) (January 1979 to 31 December 2014), British Library's Electronic Table of Contents (Zetoc) (January 1993 to 7 May 2014). We looked for trials listed on the the metaRegister of Controlled Trials (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en), Chinese Clinical Trial Registry, the U.S. Food and Drug Administration (FDA) (www.fda.gov/), National Institute for Health and Clinical Excellence (NICE) (www.

EVIDENCE

nhs.uk) and the European Medicines Agency (EMA) (www.ema.europa.eu/ema/) as of 31 December 2014. There were no language or date restrictions in the search for trials. We also culled literature digests and conference proceedings as of 15 April 2014. There were no language or date restrictions in the search for trials.

SELECTION CRITERIA

Randomised and quasi-randomised trials of HSV dendritic or geographic epithelial keratitis were included that reported the proportion of eyes healed at one week, two weeks, or both after enrolment.

DATA COLLECTION AND ANALYSIS

We tabulated data on study characteristics, risk of bias, and outcomes and used direct comparisons to estimate a risk ratio (RR) and, when feasible, a hazard ratio (HR) with a 95% confidence interval (CI). Heterogeneity was assessed by an inconsistency index. A multiple treatment comparison meta-analysis consolidated direct and indirect comparisons of relative healing at 14 days.

MAIN RESULTS

One hundred thirty-seven studies involving 8333 eyes met the inclusion criteria. Placebo-controlled studies were heterogeneous in comparison with idoxuridine (RR 1.74; 95% CI 1.03 to 2.91) and few in number for vidarabine (RR 1.81; 95% CI 1.09 to 3.01), interferon (RR 1.32; 95% CI 1.06 to 1.64), and debridement. Vidarabine (RR 1.13; 95% CI 1.02 to 1.25), trifluridine (RR 1.30; 95% CI 1.18 to 1.43), acyclovir (RR 1.23; 95% CI 1.14 to 1.34), and brivudine (RR 1.34; 95% CI 1.18 to 1.51) were more effective than idoxuridine. Trifluridine (RR 1.17; 95% CI 1.03 to 1.32) and acyclovir (RR 1.11; 95% CI 1.03 to 1.19) were more effective than vidarabine. No significant differences in healing emerged among trifluridine, acyclovir, brivudine, and foscarnet although few studies compared brivudine or foscarnet with other antivirals. Any potential advantage of ganciclovir compared to acyclovir was mitigated by study heterogeneity and possible publication bias. Only one study evaluated the joint use of two topical antivirals. In a limited number of studies, oral acyclovir (RR 0.92; 95% CI 0.79 to 1.07) or the combination of oral acyclovir with a topical antiviral (RR 1.36; 95% CI 0.68 to 2.74) appeared as effective as a single topical antiviral agent. Compared to topical antiviral monotherapy, the combination of an antiviral with either interferon or debridement had inconsistent effects on expediting healing and improving outcome.

AUTHORS' CONCLUSIONS

Placebo-controlled studies of HSV epithelial keratitis are limited to superseded interventions. Trifluridine and acyclovir are more effective than idoxuridine or vidarabine and similar in therapeutic effectiveness. Brivudine and foscarnet do not substantially differ in effectiveness from trifluridine or acyclovir. Ganciclovir is at least as effective as acyclovir. The addition of interferon to a nucleoside antiviral agent and the combination of debridement with antiviral treatment need to be further assessed to substantiate any possible advantage in healing.

Ocular herpes: the pathophysiology, management and treatment of herpetic eye diseases

Herpesviruses are a prominent cause of human viral disease, second only to the cold and influenza viruses. Most herpesvirus infections are mild or asymptomatic. However, when the virus invades the eye, a number of pathologies can develop and its associated sequelae have become a considerable source of ocular morbidity. The most common culprits of herpetic eye disease are the herpes simplex virus (HSV), varicella zoster virus (VZV), and cytomegalovirus (CMV). While primary infection can produce ocular disease, the most destructive manifestations tend to arise from recurrent infection. These recurrent infections can wreck devastating effects and lead to irreversible vision loss accompanied by a decreased quality of life, increased healthcare usage, and significant cost burden. Unfortunately, no method currently exists to eradicate herpesviruses from the body after infection. Treatment and management of herpes-related eye conditions continue to revolve around antiviral drugs, although corticosteroids, interferons, and other newer therapies may also be appropriate depending on the disease presentation. Ultimately, the advent of effective vaccines will be crucial to preventing herpesvirus diseases altogether and cutting the incidence of ocular complications.

Ganciclovir ophthalmic gel 0.15% for the treatment of acute herpetic keratitis: background, effectiveness, tolerability, safety, and future applications

Eye disease due to herpes simplex virus (HSV) is a leading cause of ocular morbidity and the number one infectious cause of unilateral corneal blindness in the developed parts of the globe. Recurrent keratitis can result in progressive corneal scarring, thinning, and vascularization. Antiviral agents employed against HSV have primarily been nucleoside analogs. Early generation drugs included idoxuridine, iododesoxycytidine, vidarabine, and trifluridine. While effective, they tended to have low bioavailability and measurable local cellular toxicity due to their nonselective mode of action. Acyclovir 0.3% ointment is a more selective agent, and had become a first-line topical drug for acute HSV keratitis in Europe and other places outside of the US. Ganciclovir 0.15% gel is the most recently approved topical treatment for herpes keratitis. Compared to acyclovir 0.3% ointment, ganciclovir 0.15% gel has been shown to be better tolerated and no less effective in several Phase II and III trials. Additionally, topical ganciclovir does not cause adverse systemic side effects and is therapeutic at lower concentrations. Based on safety, efficacy, and tolerability, ganciclovir 0.15% gel should now be considered a front-line topical drug in the treatment of dendritic herpes simplex epithelial keratitis. Topics of future investigation regarding other potential uses for ganciclovir gel may include the prophylaxis of recurrent HSV epithelial keratitis, treatment of other forms of ocular disease caused by herpesviruses and adenovirus, and ganciclovir gel as an adjunct to antitumor therapy.

Herpes simplex keratitis-induced endophthalmitis in a patient with AIDS with disseminated tuberculosis

We present the case of a 42-year-old man with AIDS who had lost complete vision of his left eye for the past 15 days. MRI and brightness scan ultrasonography were performed on his eyes that suggested of endophthalmitis with dendritic involvement in the left eye. Viral DNA PCR was performed in aqueous humour sample that confirmed the presence of herpes simplex virus and showed a negative result for cytomegalovirus. The patient was treated with a high dose of oral acyclovir for 10 days and long-term topical acyclovir. Neodymium-doped yttrium aluminum garnet procedure was performed to clear up the cornea, and intraocular pressure was controlled with brimonidine and timolol maleate. The patient was diagnosed to have disseminated tuberculosis (tuberculoma of the brain) and was started with antituberculosis therapy. His condition improved significantly after the treatment, and keratitis in cornea started to clean up.

Novel composite efficacy measure to demonstrate the rationale and efficacy of combination antiviral-anti-inflammatory treatment for recurrent herpes simplex labialis

Historically, the primary target for research and treatment of recurrent herpes simplex labialis (HSL) has been limited to inhibiting herpes simplex virus (HSV) replication. Antiviral monotherapy, however, has proven only marginally effective in curtailing the duration and severity of recurrent lesions. Recently, the role of inflammation in the progression and resolution of recurrences has been identified as an additional target. This was evaluated in a randomized study comparing combination topical 5% acyclovir-1% hydrocortisone cream (AHC) with 5% acyclovir alone (AC; in the AHC vehicle) and the vehicle. The efficacy of each topical therapy was evaluated for cumulative lesion size--a novel composite efficacy endpoint incorporating episode duration, lesion area, and proportion of nonulcerative lesions. In that study, cumulative lesion area was significantly decreased with AHC compared with AC (25% decrease; P<0.05) and the vehicle (50% decrease; P<0.0001). As research continues in this arena, cumulative lesion area should be included as a measure of efficacy in clinical trials of recurrent HSL therapies.

Diversity of microbial species implicated in keratitis: a review

Background:

Microbial keratitis is an infectious disease of the cornea characterised by inflammation and is considered an ophthalmic emergency requiring immediate attention. While a variety of pathogenic microbes associated with microbial keratitis have been identified, a comprehensive review identifying the diversity of species has not been completed.

Methods:

A search of peer-reviewed publications including case reports and research articles reporting microorganims implicated in keratitis was conducted. Search engines including PubMed, Scopus and Web of Science with years ranging from 1950-2012 were used.

Results:

232 different species from 142 genera, representing 80 families were found to be implicated in microbial keratitis. Fungi exhibited the largest diversity with 144 species from 92 genera. In comparison, 77 species of bacteria from 42 genera, 12 species of protozoa from 4 genera and 4 types of virus were identified as the infectious agents. A comparison of their aetiologies shows reports of similarities between genera.

Conclusions:

The diversity of microbial species implicated in keratitis has not previously been reported and is considerably greater than suggested by incidence studies. Effective treatment is heavily reliant upon correct identification of the responsible microorganisms. Species identification, the risk factors associated with, and pathogenesis of microbial keratitis will allow the development of improved therapies. This review provides a resource for clinicians and researchers to assist in identification and readily source treatment information.

Ocular herpes simplex virus: how are latency, reactivation, recurrent disease and therapy interrelated?

Most humans are infected with herpes simplex virus (HSV) type 1 in early childhood and remain latently infected throughout life. While most individuals have mild or no symptoms, some will develop destructive HSV keratitis. Ocular infection with HSV-1 and its associated sequelae account for the majority of corneal blindness in industrialized nations. Neuronal latency in the peripheral ganglia is established when transcription of the viral genome is repressed (silenced) except for the latency-associated transcripts and microRNAs. The functions of latency-associated transcripts have been investigated since 1987. Roles have been suggested relating to reactivation, establishment of latency, neuronal protection, antiapoptosis, apoptosis, virulence and asymptomatic shedding. Here, we review HSV-1 latent infections, reactivation, recurrent disease and antiviral therapies for the ocular HSV diseases.

Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Eye disease due to herpes simplex virus (HSV) commonly presents as epithelial keratitis.

OBJECTIVES

To compare the relative effectiveness of antiviral agents, interferon, and corneal débridement in the treatment of acute HSV epithelial keratitis.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2010, Issue 4), MEDLINE (January 1950 to October 2010), EMBASE (January 1980 to October 2010), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2010), Zetoc (British Library's Electronic Table of Contents), System for Information on Grey Literature in Europe (openSIGLE), Biosciences Information Service (BIOSIS), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), Japan Information Center of Science and Technology (JICST-EPlus), and China Academic Journals database (CAJ) via China National Knowledge Infrastructure (CNKI) with citations confirmed using China/Asia On Demand (COAD). There were no language or date restrictions in the search for trials. All databases except CNKI and COAD were last searched on 27 October 2010, CNKI and COAD were searched on 1 April 2010. We also searched literature digests, conference proceedings and reference lists.

SELECTION CRITERIA

Of 152 eligible studies,106 comparative treatment trials involving 5872 eyes with dendritic or geographic epithelial keratitis were analysed for corneal healing over two weeks.

DATA COLLECTION AND ANALYSIS

Interventions were compared at 14 days after trial enrolment by calculating a risk ratio (RR) that was adjusted with indirect RR, assessed by an inconsistency index (I(2) ) and supplemented by a seven-day RR and a hazard ratio (HR).

MAIN RESULTS

Idoxuridine, though uncertainly better in healing outcome than control because of few trials with 14-day follow up, allowed earlier corneal re-epithelialisation. Vidarabine resulted in a significantly better outcome than placebo in one trial (RR 1.96; 95% CI 1.10 to 3.49). Compared to idoxuridine, in combined direct and indirect analyses, vidarabine (RR 1.11; 95% CI 1.03 to 1.19), trifluridine (RR 1.31; 95% CI 1.20 to 1.42), acyclovir (RR 1.23; 95% CI 1.16 to 1.31), brivudine (RR 1.38; 95% CI 1.18 to 1.61), and ganciclovir (RR 1.40; 95% CI 1.25 to 1.57) were significantly more effective. Trifluridine (RR 1.12; 95% CI 1.04 to 1.21) and acyclovir (RR 1.11; 95% CI 1.05 to 1.19) appeared more effective than vidarabine. No significant differences were found in comparisons between acyclovir, trifluridine and brivudine. The comparison of ganciclovir to acyclovir was limited by heterogeneity and possible publication bias. The joint use of two topical antivirals (RR 1.00; 95% CI 0.89 to 1.12) and the use of oral acyclovir alone (RR 0.92; 95% CI 0.79 to 1.07) or combined with a topical antiviral (RR 1.08; 95% CI 0.99 to 1.17) appeared as effective as topical antiviral therapy. Compared to antiviral monotherapy, the combination of an antiviral with interferon (RR 1.03; 95% CI 0.99 to 1.07) or with débridement (RR 1.04; 95% CI 0.95 to 1.14) did not yield significantly better outcomes but may have accelerated healing. The corneal epithelial healing outcome was improved when antiviral therapy was added to débridement (RR 1.21; 95% CI 1.04 to 1.42).

AUTHORS' CONCLUSIONS

Trifluridine and acyclovir are more effective than idoxuridine or vidarabine, and similar in therapeutic effectiveness. Brivudine and ganciclovir are at least as effective as acyclovir. While not improving outcome, the combination of interferon and an antiviral agent may speed healing. The effectiveness of corneal epithelial débridement is improved by an antiviral agent.

Transcorneal permeation of L- and D-aspartate ester prodrugs of acyclovir: delineation of passive diffusion versus transporter involvement

PURPOSE

The aim of this study was to evaluate the contribution of amino acid transporters in the transcorneal permeation of the aspartate (Asp) ester acyclovir (ACV) prodrug.

METHODS

Physicochemical characterization, solubility and stability of acyclovir L-aspartate (L-Asp-ACV) and acyclovir D-aspartate (D-Asp-ACV) were studied. Transcorneal permeability was evaluated across excised rabbit cornea.

RESULTS

Solubility of L-Asp-ACV and D-Asp-ACV were about twofold higher than that of ACV. The prodrugs demonstrated greater stability under acidic conditions. Calculated pK(a) and logP values for both prodrugs were identical. Transcorneal permeability of L-Asp-ACV (12.1 +/- 1.48 x 10(-6) cm/s) was fourfold higher than D-Asp-ACV (3.12 +/- 0.36 x 10(-6) cm/s) and ACV (3.25 +/- 0.56 x 10(-6) cm/s). ACV generation during the transport process was minimal. L-Asp-ACV transport was sodium and energy dependent but was not inhibited by glutamic acid. Addition of BCH, a specific B(0,+) and L amino acid transporter inhibitor, decreased transcorneal L-Asp-ACV permeability to 2.66 +/- 0.21 x 10(-6) cm/s. L-Asp-ACV and D-Asp-ACV did not demonstrate significant difference in stability in ocular tissue homogenates.

CONCLUSION

The results demonstrate that enhanced transport of L-Asp-ACV is as a result of corneal transporter involvement (probably amino acid transporter B(0,+)) and not as a result of changes in physicochemical properties due to prodrug derivatization (permeability of D-Asp-ACV and ACV were not significantly different).

Ocular HSV-1 latency, reactivation and recurrent disease

Ocular infection with HSV-1 continues to be a serious clinical problem despite the availability of effective antivirals. Primary infection with HSV-1 can involve ocular and adenaxial sites and can manifest as blepharitis, conjunctivitis, or corneal epithelial keratitis. After initial ocular infection, HSV-1 can establish latent infection in the trigeminal ganglia for the lifetime of the host. During latency, the viral genome is retained in the neuron without producing viral proteins. However, abundant transcription occurs at the region encoding the latency-associated transcript, which may play significant roles in the maintenance of latency as well as neuronal reactivation. Many host and viral factors are involved in HSV-1 reactivation from latency. HSV-1 DNA is shed into tears and saliva of most adults, but in most cases this does not result in lesions. Recurrent disease occurs as HSV-1 is carried by anterograde transport to the original site of infection, or any other site innervated by the latently infected ganglia, and can reinfect the ocular tissues. Recurrent corneal disease can lead to corneal scarring, thinning, stromal opacity and neovascularization and, eventually, blindness. In spite of intensive antiviral and anti-inflammatory therapy, a significant percentage of patients do not respond to chemotherapy for herpetic necrotizing stromal keratitis. Therefore, the development of therapies that would reduce asymptomatic viral shedding and lower the risks of recurrent disease and transmission of the virus is key to decreasing the morbidity of ocular herpetic disease. This review will highlight basic HSV-1 virology, and will compare the animal models of latency, reactivation, and recurrent ocular disease to the current clinical data.