Herpetic Eye Disease Study. A controlled trial of topical corticosteroids for herpes simplex stromal keratitis

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.

Emerging drugs for the treatment of herpetic keratitis

INTRODUCTION

Herpes simplex keratitis stands as a prominent factor contributing to infectious blindness among developed nations. On a global scale, over 60% of the population tests positive for herpes simplex virus type-1 (HSV-1). Despite these statistics, there is currently no vaccine available for the virus. Moreover, the conventional nucleoside drugs prescribed to patients are proving ineffective in addressing issues related to drug resistance, recurrence, latency, and the escalating risk of vision loss. Hence, it is imperative to continually explore all potential avenues to restrict the virus. This review article centers on the present treatment methods for HSV-1 keratitis (HSK), highlighting the ongoing clinical trials. It delves into the emerging drugs, their mode-of-action and future therapeutics.

AREAS COVERED

The review focuses on the significance of a variety of small molecules targeting HSV-1 lifecycle at multiple steps. Peer-reviewed articles and abstracts were searched in MEDLINE, PubMed, Embase, and clinical trial websites.

EXPERT OPINION

The exploration of small molecules that target specific pathways within the herpes lifecycle holds the potential for substantial impact on the antiviral pharmaceutical market. Simultaneously, the pursuit of disease-specific biomarkers has the capacity to usher in a transformative era in diagnostics within the field.

Antiviral and Anti-Inflammatory Therapeutic Interventions for Treating Herpes Stromal Keratitis: A Systematic Review

PURPOSE

Herpes stromal keratitis (HSK) is an immune-mediated corneal inflammation that occurs after a herpes simplex virus infection. This paper aims to systematically identify and compare interventions for treating HSK and their patient outcomes.

METHODS

This systematic review followed the PRISMA methodology. Online databases were searched to obtain all relevant papers. Two independent reviewers screened through 168 records. Seven papers were included and used for data extraction. A qualitative analysis was conducted.

RESULTS

HSK patients receiving prednisolone phosphate and acyclovir showed a higher treatment success rate and significantly longer time to failure compared to patients receiving only acyclovir (P < .001). No difference in resolution time was found between oral and topical acyclovir. Between groups receiving dexamethasone and flurbiprofen, resolution occurred in 93% and 67% of patients, and BCVA (LogMAR) improved from 1.0 to 0.30 and 0.48, respectively. BCVA improved in both cyclosporine-A (P < .001) and its control (prednisolone) groups (P = .002). A tacrolimus treatment group showed greater improvement in BCVA compared to its control (prednisolone) group (P < .001).

CONCLUSION

Corticosteroids and antivirals managed HSK most effectively only when used concurrently. Oral acyclovir showed similar effectiveness to its ointment counterpart, a preferable alternative for easier administration. Corticosteroid use could induce greater therapeutic benefits when tapered in concentration and frequency and administrated for at least 10 weeks. Anti-inflammatory drugs including flurbiprofen, cyclosporine-A, and tacrolimus could be safe and effective for treating HSK. Future long-term follow-up and RCTs could provide insights on the therapeutic benefits of these potential alternatives.

Infectious and Noninfectious Corneal Ulcers in Ocular Graft-Versus-Host Disease: Epidemiology, Clinical Characteristics, and Outcomes

PURPOSE

To evaluate the incidence, clinical characteristics, microbiological profile, and therapeutic outcomes of corneal ulcers in individuals with chronic ocular graft-vs-host disease (coGVHD).

DESIGN

Retrospective clinical cohort study.

METHODS

Review of individuals diagnosed with coGVHD following hematopoietic stem cell transplantation (HSCT) who were seen at the Bascom Palmer Eye Institute between May 2010 and November 2021. Baseline demographics, clinical characteristics, microbiological profile, risk factors for corneal ulceration, and treatment outcomes were collected. Etiology was deemed infectious in individuals with a positive culture or appropriate clinical scenario (presence of stromal infiltrate or hypopyon); otherwise, ulcers were presumed to be noninfectious. Treatment success was defined as reepithelialization with infiltrate resolution, and treatment failure as progression to corneal perforation or keratoplasty. Kaplan-Meier survival analysis estimated the incidence of ulceration. Cox regression analyses examined demographic and risk factors. Infectious and noninfectious ulcer groups were compared using 2-way independent t tests, 1-way analysis of variances, and χ2 tests, as appropriate.

RESULTS

173 individuals were included (53.7±14.4 years old; 59.0% male). Thirty-three individuals developed an ulcer 74.5±54.3 months after HSCT, with estimated 5- and 10-year incidences of 14% and 30%, respectively. Twenty-two (66.6%) ulcers were deemed infectious (15 microbiologically confirmed, 7 clinically) and 11 (33.3%) were deemed noninfectious. Risk factors for corneal ulceration included Black race (hazards ratio [HR] 2.89, 95% CI 1.30-6.42, P < .01), previous ocular surgery (HR 9.16, 95% CI 3.86-21.72, P < .01), eyelid margin abnormalities (HR 3.44, 95% CI 1.69-6.99, P < .01), and topical steroid use (HR 2.74, 95% CI 1.33-5.62, P < .01). Conversely, contact lens use reduced the risk of corneal ulceration (HR 0.29, 95% CI 0.13-0.66, P < .01). Infectious ulcers had a significantly higher frequency of treatment failure than noninfectious ulcers (57.1% vs 20.0%, P = .04).

CONCLUSION

Corneal ulceration is a potential complication of coGVHD, with several clinical features identified as risk factors. Infectious ulcers had worse outcomes than noninfectious ulcers.

Corneal ring infiltrate- far more than Acanthamoeba keratitis: review of pathophysiology, morphology, differential diagnosis and management

OBJECTIVE

Ring infiltrates usually accompany numerous infectious and sterile ocular disorders. Nevertheless, systemic conditions, drugs toxicity and contact lens wear may present with corneal ring infiltrate in substantial part. Considering its detrimental effect on vision, detailed knowledge on etiology, pathophysiology, differential diagnosis, and management should be considered essential for every ophthalmologist.

METHODS

The PUBMED database was searched for "corneal ring infiltrate" and "ring infiltrate" phrases, "sterile corneal infiltrate" and "corneal infiltrate". We analyzed articles written in English on risk factors, pathophysiology, clinical manifestation, morphological features, ancillary tests (anterior-segment optical coherence tomography, corneal scraping, in vivo confocal microscopy), differential diagnosis and management of corneal ring infiltrate.

RESULTS

Available literature depicts multifactorial origin of corneal ring infiltrate. Dual immunological pathophysiology, involving both antibodies-dependent and -independent complement activation, is underlined. Furthermore, we found that the worldwide most prevalent among non-infectious and infectious ring infiltrates are ring infiltrates related to contact-lens wear and bacterial keratitis respectively. Despite low incidence of Acanthamoeba keratitis, it manifests with corneal ring infiltrate with the highest proportion of the affected patients (one third). However, similar ring infiltrate might appear as a first sign of general diseases manifestation and require targeted treatment. Every corneal ring infiltrate with compromised epithelium should be scraped and treat as an infectious infiltrate until not proven otherwise. Of note, microbiological ulcer might also lead to immunological ring and therefore require anti-inflammatory treatment.

CONCLUSION

Corneal ring infiltrate might be triggered not only by ocular infectious and non-infectious factors, but also by systemic conditions. Clinical assessment is crucial for empirical diagnosis. Furthermore, treatment is targeted towards the underlying condition but should begin with anti-infectious regimen until not proven otherwise.

Steroids in the Management of Infectious Keratitis

PURPOSE

To summarize the evidence base on the use of topical corticosteroids for infectious keratitis.

METHODS

Narrative review.

RESULTS

Infectious keratitis is a painful condition that often results in visually significant corneal stromal scarring, even when antimicrobial therapy is successful. Corticosteroids may reduce inflammation and subsequent scar formation and while relieving the acute ocular pain associated with a corneal ulcer. However, corticosteroids also reduce the host immune response, which could hinder the ability to clear infection. The safety and effectiveness of corticosteroids depends to a large part on the efficacy of the antimicrobials being used to treat the underlying infection. Randomized trials have found that corticosteroids are safe and effective for herpetic keratitis when used with appropriate antiviral therapy, and are safe for bacterial keratitis when used with broad spectrum topical antibiotics. The effectiveness of corticosteroids for bacterial keratitis has not been shown conclusively, although more advanced bacterial corneal ulcers may do better with corticosteroids. No randomized trials have assessed the safety and effectiveness of steroids for fungal or acanthamoeba keratitis. Animal studies suggest corticosteroids may be harmful in fungal keratitis, and observational human studies have found that steroids are harmful for fungal and acanthamoeba keratitis when started prior to anti-amoebics.

CONCLUSIONS

Topical corticosteroids, when used as an adjunct to antimicrobial therapy, may be beneficial if the antimicrobial being used can effectively clear or suppress the infection, such as in bacterial and herpetic keratitis. Randomized trials would be helpful to further delineate the role of corticosteroids for infectious keratitis.

The Host-Pathogen Interplay: A Tale of Two Stories within the Cornea and Posterior Segment

Ocular infectious diseases are an important cause of potentially preventable vision loss and blindness. In the following manuscript, we will review ocular immunology and the pathogenesis of herpesviruses and Pseudomonas aeruginosa infections of the cornea and posterior segment. We will highlight areas of future research and what is currently known to promote bench-to-bedside discoveries to improve clinical outcomes of these debilitating ocular diseases.

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.

Host-microbe interactions in cornea

Corneal infections result through interaction between microbes and host innate immune receptors. Damage to the cornea occurs as a result of microbial virulence factors and is often exacerbated by lack of a controlled host immune response; the latter contributing to bystander damage to corneal structure. Understanding mechanisms involved in host microbial interactions is critical to development of novel therapeutic targets, ultimate control of microbial pathogenesis, and restoration of tissue homeostasis. Studies on these interactions continue to provide exciting findings directly related to this ultimate goal.

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.

COMPARATIVE EFFICACY OF ANTIVIRAL AGENTS FOR PREVENTION AND MANAGEMENT OF HERPES LABIALIS: A SYSTEMATIC REVIEW AND NETWORK META-ANALYSIS

OBJECTIVE

To compare the relative efficacy and safety of antiviral agents used in the prevention and management of herpes labialis through a network meta-analysis of clinical trials.

METHODS

A systematic search was performed in Ovid Medline PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus and Clinicaltrials.gov for randomized controlled trials (RCTs) reporting a comparison of antiviral agents in the management and prevention of herpes labialis in healthy/immunocompetent adults. The data extracted from the selected RCTs were assessed and a network meta-analysis (NMA) was performed. The interventions were ranked according to the surface under the cumulative ranking (SUCRA).

RESULTS

A total of 52 articles were included for qualitative synthesis and for the quantitative part, 26 articles were analyzed for the primary treatment outcome and 7 studies were analyzed for the primary prevention outcome. The combination therapy of oral valacyclovir and topical clobetasol was the best ranked with a mean reduction in healing time of -3.50 (95% CI -5.22 to -1.78) followed by vidarabine monophosphate of -3.22 (95% CI -4.59 to -1.85). No significant inconsistencies, heterogeneity, and publication bias were reported for TTH outcome analysis. For primary prevention outcomes, only 7 RCTs fulfilled the inclusion criteria, and none of the interventions was shown to be superior to each other. The absence of adverse events was reported by 16 studies, whereas other studies reported mild side effects only.

CONCLUSION

NMA highlighted that several agents were effective in the management of herpes labialis among which the combination of oral valacyclovir with topical clobetasol therapy was the most effective in reducing the time to heal. However, further studies are required to determine which intervention is the most effective in preventing the recurrence of herpes labialis.

Mediators of the Effect of Corneal Cross-Linking on Visual Acuity for Fungal Ulcers: A Prespecified Secondary Analysis From the Cross-Linking-Assisted Infection Reduction Trial

PURPOSE

The purpose of this study was to determine whether astigmatism or corneal scarring is mediating the reduced visual acuity among patients with fungal keratitis randomized to corneal cross-linking (CXL).

DESIGN

This was a prespecified exploratory outcome from an outcome-masked, 2 × 2 factorial design, randomized controlled clinical trial.

STUDY PARTICIPANTS

Consecutive patients presented with moderate vision loss from a smear-positive fungal ulcer at Aravind Eye Hospital, Madurai, India.

INTERVENTION

Study eyes were randomized to one of 4 treatment combinations using an adaptive randomization protocol. The treatment arms included (1) topical natamycin 5% alone, (2) topical natamycin 5% plus CXL, (3) topical amphotericin B 0.15% alone, and (4) topical amphotericin 0.15% plus CXL. Best spectacle-corrected visual acuity (BSCVA), contact lens over-refraction, and scar size and depth as measured by a masked study ophthalmologist using a standardized protocol were recorded at 3 months. Pentacam Scheimpflug imaging was also obtained at 3 months.

MAIN OUTCOME MEASURES

BSCVA and contact lens over-refraction, infiltrate and/or scar size and depth, total astigmatism of the front and back of the cornea, total lower-order and higher-order aberrations of the anterior and posterior cornea, and total densitometry of the anterior, central, and posterior stroma were recorded. We performed a mediation analysis looking at the proportion of the effect of CXL on BSCVA that was mediated through scar size, scar depth, astigmatism and density.

RESULTS

BSCVA at 3 months was available for 99 of 111 patients (89%) who had a mean of 0.82-LogMAR (SD 0.68). Three-month infiltrate and/or scar size ( P < 0.001), depth ( P < 0.001), and densitometry ( P = 0.001) were statistically significant predictors of 3-month BSCVA. Astigmatism seemed to mediate 23% of the effect of CXL on BSCVA, whereas scar size mediated 23%, scar depth 17%, and densitometry 7%.

CONCLUSIONS

Corneal scarring and astigmatism are mediators of worse visual acuity after cross-linking in fungal keratitis. Corneal densitometry may be a helpful cornea-specific variable for clinicians and researchers in determining the effect of corneal scarring on visual acuity in specific patients and as an objective study outcome.

TRIAL REGISTRATION

NCT02570321.

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.

Outcomes and prognostic factors of cataract surgery in cytomegalovirus-related anterior uveitis

PURPOSE

To evaluate the outcomes of cataract surgery in patients with cytomegalovirus (CMV) anterior uveitis and factors associated with final visual outcome.

SETTING

Hong Kong Eye Hospital, Hong Kong.

DESIGN

Retrospective case series.

METHODS

History, clinical characteristics, corrected distance visual acuity (CDVA), medications, and complications of CMV anterior uveitic eyes that underwent cataract surgery between 2010 and 2020 were reviewed.

RESULTS

This study included 26 eyes of 26 patients undergoing phacoemulsification. The median duration of disease was 4.8 years, and the median quiescent period preoperatively was 2.3 years. None required pupil manipulation or had significant intraoperative complications. The median CDVA improved from 20/100 (interquartile range [IQR] 20/200 to 20/50) preoperatively to 20/30 (IQR 20/40 to 20/25) at 1 year and 20/35 (IQR 20/50 to 20/30) at the last follow-up at a median of 4.9 years postoperatively ( P < .001). CDVA improved in 19 eyes (73.1%) and was ≥20/40 in 18 eyes (69.2%). In the multivariate regression model, preoperative use of topical 0.15% ganciclovir (β = 0.33, 95% CI 0.17 to 0.48, P < .001) and adjunctive intraoperative intracameral dexamethasone 0.4 mg (β = 0.19, 95% CI 0.01 to 0.36, P = .043) were associated with a better final CDVA. Loss of CDVA and poor postoperative CDVA visual acuity were mostly attributed to uveitic glaucoma, but preoperative glaucoma or the number of antiglaucoma medications did not affect final CDVA.

CONCLUSIONS

Cataract surgery in eyes with CMV anterior uveitis was safe and CDVA significantly improved and remained sustained postoperatively. Topical ganciclovir 0.15% preoperatively and intracameral corticosteroid intraoperatively seem to maximize the final visual outcome.

Topical Chlorhexidine 0.2% versus Topical Natamycin 5% for the Treatment of Fungal Keratitis in Nepal: A Randomized Controlled Noninferiority Trial

PURPOSE

To investigate if topical chlorhexidine 0.2%, which is low cost and easy to formulate, is noninferior to topical natamycin 5% for the treatment of filamentous fungal keratitis.

DESIGN

Randomized controlled, single-masked, noninferiority clinical trial.

PARTICIPANTS

Adults attending a tertiary-level ophthalmic hospital in Nepal with filamentous fungal infection confirmed on smear or confocal microscopy.

METHODS

Participants were randomly allocated to receive topical chlorhexidine 0.2% or topical natamycin 5%. Primary analysis (intention-to-treat) was by linear regression, using baseline logarithm of the minimum angle of resolution (logMAR) best spectacle-corrected visual acuity (BSCVA) and treatment arm as prespecified covariates. Mixed fungal-bacterial infections were excluded from the primary analysis but included in secondary analyses and secondary safety-related outcomes. The noninferiority margin was 0.15 logMAR. This trial was registered with ISRCTN, number ISRCTN14332621.

MAIN OUTCOME MEASURES

The primary outcome measure was BSCVA at 3 months. Secondary outcome measures included perforation or therapeutic penetrating keratoplasty by 90 days.

RESULTS

Between June 3, 2019, and November 9, 2020, 354 eligible participants were enrolled and randomly assigned: 178 to chlorhexidine and 176 to natamycin. Primary outcome data were available for 153 and 151 of the chlorhexidine and natamycin groups, respectively. Of these, mixed bacterial-fungal infections were found in 20 cases (12/153 chlorhexidine, 8/151 natamycin) and excluded from the primary analysis. Therefore, 284 patients were assessed for the primary outcome (141 chlorhexidine, 143 natamycin). We did not find evidence to suggest chlorhexidine was noninferior to natamycin and in fact found strong evidence to suggest that natamycin-treated participants had significantly better 3-month BSCVA than chlorhexidine-treated participants, after adjusting for baseline BSCVA (regression coefficient, -0.30; 95% confidence interval [CI], -0.42 to -0.18; P < 0.001). There were more perforations and emergency corneal grafts in the chlorhexidine arm (24/175, 13.7%) than in the natamycin arm (10/173, 5.8%; P = 0.018, mixed infections included), whereas natamycin-treated cases were less likely to perforate or require an emergency corneal graft, after adjusting for baseline ulcer depth (odds ratio, 0.34; 95% CI, 0.15-0.79; P = 0.013).

CONCLUSIONS

Treatment with natamycin is associated with significantly better visual acuity, with fewer adverse events, compared with treatment with chlorhexidine. Natamycin remains the preferred first-line monotherapy treatment for filamentous fungal keratitis.

Modulating glutamine metabolism to control viral immuno-inflammatory lesions

Infection of the cornea with HSV results in an immune-inflammatory reaction orchestrated by proinflammatory T cells that is a major cause of human vision impairment. The severity of lesions can be reduced if the representation of inflammatory T cells is changed to increase the presence of T cells with regulatory function. This report shows that inhibiting glutamine metabolism using 6-Diazo-5-oxo-l-norleucine (DON) administered via intraperitoneal (IP) starting 6 days after ocular infection and continued until day 15 significantly reduced the severity of herpetic stromal keratitis lesions. The therapy resulted in reduced neutrophils, macrophages as well proinflammatory CD4 Th1 and Th17 T cells in the cornea, but had no effect on levels of regulatory T cells. A similar change in the representation of inflammatory and regulatory T cells occurred in the trigeminal ganglion (TG) the site where HSV infection establishes latency. Glutamine metabolism was shown to be required for the in-vitro optimal induction of both Th1 and Th17 T cells but not for the induction of Treg that were increased when glutamine metabolism was inhibited. Inhibiting glutamine metabolism also changed the ability of latently infected TG cells from animals previously infected with HSV to reactivate and produce infectious virus.

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.

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.

Efficacy of Voriconazole Corneal Intrastromal Injection for the Treatment of Fungal Keratitis

Purpose

To evaluate efficacy and safety of novel tricyclic corneal stroma injection (TCSI) voriconazole for the treatment of fungal keratitis.

Methods

This retrospective cohort study included data of 57 patients (57 eyes) with fungal keratitis. The TCSI group consisted of 27 patients (27 eyes) who were injected voriconazole once via TCSI procedure within one week after enrollment, in addition to conventional antifungal treatment. The control group consisted of 30 patients (30 eyes) who were treated using conventional antifungal treatment modalities. The outcome measures consist of the 3-week and 3-month best-corrected visual acuity (BCVA) values and size of infiltrate or scar, time to re-epithelialization, corneal perforation rate and/or therapeutic penetrating keratoplasty (TPK) requirement, the preoperative and post-TCSI corneal endothelial cell density (ECD), and the intraocular pressure (IOP) of the treated eye and the respective contralateral eye.

Results

There were no significant differences in the baseline demographic and clinical characteristics between the two groups. 3 weeks and 3 months after enrollment, the TCSI group exhibited an increase in visual acuity (P < 0.05), and there was no significant difference in the size of infiltrate or scar between two groups (P > 0.05). Time to re-epithelialization was shorter in the TCSI group than in the control group (P < 0.05). There was no statistically significant difference between corneal ECD on the day before and 7 days after TCSI and the IOP of treated and contralateral healthy eyes on the day before and 1 day, 3 days, 7 days, and 1 month after TCSI (P > 0.05). The difference in the risk of perforation and/or TPK requirement was not statistically significant between two groups (P > 0.05).

Conclusion

Localized injection of voriconazole using TCSI may be a minimally invasive, safe, and effective adjuvant treatment modality for fungal keratitis.

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.

Noninvasive Diagnosis of Viral Keratouveitis with Retro-corneal Endothelial Plaques: A Case Series

Purpose: The aim of this study was to evaluate the noninvasive diagnostic methods in managing the herpetic keratouveitis with retro-corneal endothelial plaques.Methods: 12 patients suspected to have unilateral herpetic keratouveitis with retro-corneal endothelial plaques were included. Slit lamp photos, AS-OCT, IVCM and corneal scraping culture were taken in all cases to help diagnosing and managing the disease. All patients received systemic and topical anti-viral treatment immediately and combined with topical steroids three days later.Results: Corneal scraping culture ruled out bacterial and fungal infection. AS-OCT showed that the boundaries between the corneal endothelial surface were clear in all patients. Corneal endothelial density and subbasal nerve plexus significantly decreased in all patients. Endothelial plaques reduced or disappeared in all patients with the treatment.Conclusions: Retro-corneal endothelial plaques and hypopyon are associated clinical manifestations of viral keratouveitis. AS-OCT and IVCM enhanced early detection and assessment during the follow-ups of the disease.

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.

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.

The role of fungi in fungal keratitis

Fungal keratitis (FK) accounts for approximately half of the microbial keratitis encountered in low middle income countries (LMICs) and predominantly affect the working rural-poor. FK causes significant morbidity with the majority of patients left with moderate or worse visual impairment and approximately 25% requiring expensive and often unsuccessful surgical interventions. The severity of FK and the resultant corneal damage or resolution can be attributed to i) the virulence and bioburden of the fungal pathogen, ii) the host defense mechanism and immune response and iii) sub-optimal diagnostics and anti-fungal treatment strategies. This review provides a comprehensive overview of the multifaceted components that drive FK progression and resolution, highlighting where knowledge gaps exist and areas that warrant further research.

Management of Stromal Herpes Simplex Virus Keratitis With Epithelial Ulceration Using Optical Coherence Tomography-Generated Corneal Thickness Maps

PURPOSE

To report 2 cases of herpes simplex virus (HSV) stromal keratitis with epithelial ulceration that were managed using optical coherence tomography-generated pachymetric and corneal epithelial thickness maps.

METHODS

Two patients with a history of HSV keratitis with nonhealing epithelial defects were referred to the Athens Vision Eye Institute. Anterior segment optical coherence tomography-generated pachymetric and corneal epithelial thickness maps showed subclinical stromal edema and irregular epithelium, thus indicating diagnoses of HSV stromal keratitis with epithelial ulceration. The patients were administered topical preservative-free dexamethasone and oral antiviral therapy. Steroid tapering was guided by pachymetric and corneal epithelial thickness maps at each follow-up visit.

RESULTS

Both patients experienced initial healing of the epithelium and resolution of stromal inflammation. One patient had a recurrence of HSV stromal keratitis with epithelial defect 3 months after initial improvement, with pachymetric and corneal epithelial thickness maps indicating subclinical stromal edema. He was reintroduced to topical steroid therapy, and the stromal edema and epithelial defect subsequently resolved. Both patients have had no recurrences in the past year.

CONCLUSIONS

Pachymetric and corneal epithelial thickness maps provide an objective assessment of stromal inflammation and the following 2 clinical advantages in the management of HSV stromal keratitis with epithelial ulceration: (1) they help differentiate it from HSV epithelial keratitis with geographic ulceration and neurotrophic keratopathy and (2) offer objective measurements to guide management with topical corticosteroids until resolution of stromal edema. Thus, treatment can be initiated in a timely manner, and the blinding complications of HSV stromal keratitis can be avoided.

Cross-Linking Assisted Infection Reduction (CLAIR): A Randomized Clinical Trial Evaluating the Effect of Adjuvant Cross-Linking on Bacterial Keratitis

PURPOSE

To determine whether there is a benefit to adjuvant corneal cross-linking (CXL) for bacterial keratitis.

METHODS

This is an outcome-masked, randomized controlled clinical trial. Consecutive patients presenting with a smear-positive bacterial ulcer at Aravind Eye Hospitals at Madurai, Pondicherry, and Coimbatore in India were enrolled. Study eyes were randomized to topical moxifloxacin 0.5% or topical moxifloxacin 0.5% plus CXL. The primary outcome of the trial was microbiological cure at 24 hours on repeat culture. Secondary outcomes included best spectacle corrected visual acuity at 3 weeks and 3 months, percentage of study participants with epithelial healing at 3 weeks and 3 months, infiltrate and/or scar size at 3 weeks and 3 months, 3-day smear and culture, and adverse events.

RESULTS

Those randomized to CXL had 0.60 decreased odds of culture positivity at 24 hours (95% confidence interval [CI]: 0.10-3.50; P = 0.65), 0.9 logarithm of the minimum angle of resolution lines worse visual acuity (95% CI: -2.8 to 4.6; P = 0.63), and 0.41-mm larger scar size (95% CI: -0.48 to 1.30; P = 0.38) at 3 months. We note fewer corneal perforations or need for therapeutic penetrating keratoplasty in the CXL group.

CONCLUSIONS

We were unable to confirm a benefit to adjuvant CXL in the primary treatment of moderate bacterial keratitis. However, CXL may reduce culture positivity and complication rates; therefore, a larger trial to fully evaluate this is warranted.

TRIAL REGISTRATION

NCT02570321.

Update on Herpes simplex keratitis management

Herpes simplex keratitis (HSK) is a common, potentially blinding condition characterised by recurrent infections of the cornea, seen by both general ophthalmologists and corneal specialists. Successful treatment of recurrences reduces disease duration, prevents progressive corneal scaring leading to vision loss and reduces risk of further recurrences. In this review we discuss the relative advantages of the diagnostic laboratory investigations including polymerase chain reaction, viral culture and fluorescence-based immunohistochemistry. We review treatment strategies in selected aspects of HSK and discuss the management options in cases not responding to treatment.

Local delivery of corticosteroids in clinical ophthalmology: A review

Locally administered steroids have a long history in ophthalmology for the treatment of inflammatory conditions. Anterior segment conditions tend to be treated with topical steroids whilst posterior segment conditions generally require periocular, intravitreal or systemic administration for penetration. Over recent decades, the clinical applications of periocular steroid delivery have expanded to a wide range of conditions including macular oedema from retino-vascular conditions. Formulations have been developed with the aim to provide practical, targeted, longer-term and more efficacious therapy whilst minimizing side effects. Herein, we provide a comprehensive overview of the types of periocular steroid delivery, their clinical applications in ophthalmology and their side effects.

Ocular manifestations of herpes simplex virus

PURPOSE OF REVIEW

To review ocular manifestations and complications of herpes simplex virus (HSV) and discuss recent advancements in diagnostic and treatment strategy.

RECENT FINDINGS

In-vivo confocal microscopy has expanded our understanding of corneal nerve degeneration, corneal dendritic cell activity, and changes in biomechanical properties in HSV keratitis. Although currently available only as a research tool, metagenomic deep sequencing has the potential to improve diagnostic accuracy beyond the well established PCR technology, especially in atypical cases. Development of an HSV vaccine has shown some encouraging results in a murine model. New treatment options for neurotrophic cornea offer promise, specifically cenegermin nerve growth factor.

SUMMARY

Ocular herpes simplex infection and its complications continue to cause significant visual burden and decreased quality of life. Familiarity with its clinical features, wider adoption of viral PCR diagnostic technology, and recognition of the need for long-term maintenance medications for recurrent or chronic cases form the basis for effective management. Metagenomic deep sequencing, the development of a herpes vaccine, and cenegermin nerve growth factor offer promise as diagnostic, preventive, and therapeutic options, respectively.

The Binary Classification Of Chronic Diseases

Acute diseases start with an insult and end when insult disappears. If the trauma induces an immune reaction (which happens in most cases), this reaction must be terminated with some type of resolution mechanism, when the cause of the trauma ceases. Chronicity develops if insult is permanent or if the resolution mechanism is defective. Another way to reach disease chronicity is a positive feedback loop, whereby the immune reaction activates an internal, insult-like reaction. A distinction between chronic states characterized by a persistent, low suppressive effect and those characterized by a persistent, high suppressive effect of regulatory T cells (Treg), is proposed. This two-class division represents two ways to reach chronicity: (a) by maintaining inflammatory reaction long after insult disappears (“low Treg”), or (b) by suppressing inflammatory reaction prior to the disappearance of insult (“high Treg”). This two-class division may explain the strong association between certain pathogens and cancer, on one hand, and between several other pathogens and autoimmunity, on the other hand. The weak association between autoimmune diseases and HIV infection and the relatively weak association between autoimmune diseases and cancer may be elucidated as well. In addition, the model rationalizes why immune-modulating drugs, which are effective in cancer, are also effective in “high Treg” viral infections, while corticosteroids, which are generally effective in autoimmune diseases, are also effective in other “low Treg” diseases (such as asthma, atopic dermatitis, and “low Treg” infections) but are not effective in solid malignancies and “high Treg” infections. Moreover, the model expounds why certain bacteria inhibit tumor growth and why these very bacteria induce autoimmune diseases.

Current and Emerging Therapies for Ocular Herpes Simplex Virus Type-1 Infections

Herpes simplex virus type-1 (HSV-1) is a neurotropic, double-stranded DNA virus that can cause a wide variety of diseases, including many ocular pathologies. It is one of the leading causes of infectious blindness in the United States. Because of its ubiquitous nature and its potential to cause serious ocular maladies, there is a significant need for more effective antiviral therapies against ocular HSV-1. In this review, we discuss the lifecycle of HSV-1 as it pertains to corneal infections and the clinically approved as well as emerging treatments to combat HSV-1 infections. We also highlight some newly identified host targets for the antiviral drug development.

Cross-Linking-Assisted Infection Reduction: A Randomized Clinical Trial Evaluating the Effect of Adjuvant Cross-Linking on Outcomes in Fungal Keratitis

PURPOSE

To determine if there is a benefit to adjuvant corneal crosslinking (CXL) and to compare natamycin versus amphotericin B for filamentous fungal keratitis.

DESIGN

Outcome-masked, 2×2 factorial design, randomized controlled clinical trial.

PARTICIPANTS

Consecutive patients presenting with moderate vision loss from a smear-positive fungal ulcer at Aravind Eye Hospital, Madurai, India.

METHODS

Study eyes were randomized to 1 of 4 treatment combinations using an adaptive randomization protocol. The treatment arms included (1) topical natamycin 5% alone, (2) topical natamycin 5% plus CXL, (3) topical amphotericin B 0.15% alone, and (4) topical amphotericin 0.15% plus CXL.

MAIN OUTCOME MEASURES

The primary outcome of the trial was microbiological cure at 24 hours on repeat culture. Secondary outcomes included best spectacle-corrected visual acuity (BSCVA) at 3 weeks and 3 months, percentage of study participants with epithelial healing at 3 days, 3 weeks, and 3 months, infiltrate or scar size at 3 weeks and 3 months, 3-day smear and culture, and adverse events.

RESULTS

Those randomized to CXL regardless of medication (topical natamycin or amphotericin) had 1.32-fold increased odds of 24-hour culture positivity, although this was not statistically significant (95% confidence interval [CI], 0.57-3.06; P = 0.51). We were also unable to find a difference in 24-hour culture positivity between those randomized to amphotericin and those randomized to natamycin when evaluating as a group regardless of whether or not they received CXL (coefficient 1.10; 95% CI, 0.47-2.54; P = 0.84). The BSCVA was approximately 0.22 logarithm of the minimum angle of resolution (logMAR) (2.2 Snellen lines) worse on average at 3 weeks among those receiving CXL regardless of medication (95% CI, -0.04 to 0.40; P = 0.04) and 0.32 logMAR (3.2 Snellen lines) worse visual acuity at 3 months after controlling for baseline visual acuity (95% CI, 0.03-0.54; P = 0.02). There was no difference in infiltrate or scar size, percentage of epithelialized or adverse events when comparing CXL with no CXL or the 2 topical medications.

CONCLUSIONS

There appears to be no benefit of adjuvant CXL in the primary treatment of moderate filamentous fungal ulcers, and it may result in decreased visual acuity.

Corneal Endotheliitis as a Presentation of Acanthamoeba Keratitis

OBJECTIVE

To report 2 cases of Acanthamoeba keratitis (AK) presenting with corneal endotheliitis.

METHODS

Case report.

RESULTS

Two contact lens wearers, who had been diagnosed with herpes simplex virus (HSV) keratitis, predominantly manifested corneal endotheliitis composed of corneal edema, keratic precipitates, and anterior chamber reaction at referral. AK was confirmed using cultures or through polymerase chain reaction testing. The patients were started on polyhexamethylene biguanide and responded favorably to regain satisfactory visual acuity.

CONCLUSIONS

Corneal endotheliitis, although uncommon, may be a manifestation of AK. We must have high-index suspicion for AK in all contact lens users, particularly before making a diagnosis of HSV keratitis. Accurate diagnosis and prompt treatment can result in a favorable prognosis for AK.

Mycotic Antimicrobial Localized Injection: A Randomized Clinical Trial Evaluating Intrastromal Injection of Voriconazole

PURPOSE

To determine if there is a benefit to adjuvant intrastromal voriconazole (ISV) injections for primary treatment of filamentous fungal keratitis.

DESIGN

Outcome-masked, randomized controlled clinical trial.

PARTICIPANTS

Patients with moderate vision loss resulting from a smear-positive fungal ulcer.

METHODS

Study eyes were randomized to topical natamycin plus ISV injection versus topical natamycin alone.

MAIN OUTCOME MEASURES

The primary outcome of the trial was microbiological cure on 3-day repeat culture analysis. Secondary outcomes included microbiological cure on 7-day repeat culture analysis; 3-week and 3-month best spectacle-corrected visual acuity; infiltrate or scar size or both; rate of perforation; therapeutic penetrating keratoplasty (TPK); and other adverse events.

RESULTS

A total of 151 patients with smear-positive ulcers were screened and 70 were enrolled at Aravind Eye Hospital, Pondicherry, India. Baseline cultures grew Fusarium in 19 samples (27%), Aspergillus in 17 samples (24%), and other filamentous fungi in 19 samples (27%) and showed negative results in 13 samples (19%). Those randomized to ISV injection had 1.82 times the odds of 3-day culture positivity after controlling for baseline culture status (95% confidence interval [CI], 0.65-5.23; P = 0.26, bias-corrected logistic regression) and 1.98 times the odds of positive 7-day culture results, after controlling for baseline culture status (95% CI, 0.69-5.91; P = 0.20, bias-corrected logistic regression). Those randomized to ISV injection showed 0.5 logMAR lines (approximately 0.5 Snellen lines) of decreased visual acuity (95% CI, -2.6 to 3.6 lines; P = 0.75) and 0.55 mm worse infiltrate or scar size or both at 3 months after controlling for baseline values (95% CI, -0.13 to 1.25; P = 0.11). Intrastromal voriconazole injections showed a 2.85-fold increased hazard of perforation after controlling for baseline infiltrate depth (95% CI, 0.76-10.75; P = 0.12) but no difference in the rate of TPK (hazard ratio, 0.95; 95% CI, 0.44-2.04; P = 0.90).

CONCLUSIONS

There seems to be no benefit to adding ISV injections to topical natamycin in the primary treatment of moderate to severe filamentous fungal ulcers. Studies consistently suggest that voriconazole has a limited role in the treatment of filamentous fungal ulcers.

Topical cyclosporine-A versus prednisolone for herpetic stromal keratitis: a randomized controlled trial

PURPOSE

To compare topical cyclosporine-A 2% eye drop (Cs-A) with prednisolone acetate 1% eye drop for treatment of herpetic stromal keratitis (HSK).

METHODS

In this randomized clinical trial, 38 eyes of 33 patients with HSK were randomly assigned to receive either 2% Cs-A or 1% prednisolone acetate eye drops. All subjects received oral acyclovir 400 mg twice a day. Slit-lamp examination, Scheimpflug tomography corneal optical densitometry (Pentacam®, Oculus Inc., Wetzlar, Germany), best-corrected visual acuity (BCVA), and intra-ocular pressure (IOP) were evaluated at the first visit, and 14 and 30 days after the treatment.

RESULTS

Within-group analysis revealed significant improvement of total cornea optical density after 30 days of treatment in both groups (30.3 ± 10.5 to 28.3 ± 9.8, p < 0.001 for prednisolone group, and 30.5 ± 8.8 to 28.8 ± 8.3 p < 0.001 for Cs-A group, mean ± SD). We were not able to disclose any significant difference between the two groups regarding the improvement of cornea optical density (p = 0.66). Best-corrected visual acuity (BCVA) logMAR significantly improved in both groups after 30 days of treatment (0.20 ± 0.52, p = 0.002 in prednisolone group, and 0.24 ± 0.31, p < 0.001 in Cs-A group, mean ± SD). Analysis between groups did not show a significant difference of BCVA improvement (p = 0.45). We did not observe any severe side effect attributable to drugs.

CONCLUSIONS

Cs-A 2% and prednisolone acetate 1% topical eye drops are effective for treatment of HSK.

Pathogenesis of herpes simplex keratitis: The host cell response and ocular surface sequelae to infection and inflammation

Herpes simplex virus type 1 (HSV) keratitis is a leading cause of infectious blindness. Clinical disease occurs variably throughout the cornea from epithelium to endothelium and recurrent HSV stromal keratitis is associated with corneal scarring and neovascularization. HSV keratitis can be associated with ocular pain and subsequent neutrophic keratopathy. Host cell interactions with HSV trigger an inflammatory cascade responsible not only for clearance of virus but also for progressive corneal opacification due to inflammatory cell infiltrate, angiogenesis, and corneal nerve loss. Current antiviral therapies target viral replication to decrease disease duration, severity and recurrence, but there are limitations to these agents. Therapies directed towards viral entry into cells, protein synthesis, inflammatory cytokines and vascular endothelial growth factor pathways in animal models represent promising new approaches to the treatment of recurrent HSV keratitis.

Update on the Management of Infectious Keratitis

Infectious keratitis is a major global cause of visual impairment and blindness, often affecting marginalized populations. Proper diagnosis of the causative organism is critical, and although culture remains the prevailing diagnostic tool, newer techniques such as in vivo confocal microscopy are helpful for diagnosing fungus and Acanthamoeba. Next-generation sequencing holds the potential for early and accurate diagnosis even for organisms that are difficult to culture by conventional methods. Topical antibiotics remain the best treatment for bacterial keratitis, and a recent review found all commonly prescribed topical antibiotics to be equally effective. However, outcomes remain poor secondary to corneal melting, scarring, and perforation. Adjuvant therapies aimed at reducing the immune response associated with keratitis include topical corticosteroids. The large, randomized, controlled Steroids for Corneal Ulcers Trial found that although steroids provided no significant improvement overall, they did seem beneficial for ulcers that were central, deep or large, non-Nocardia, or classically invasive Pseudomonas aeruginosa; for patients with low baseline vision; and when started early after the initiation of antibiotics. Fungal ulcers often have worse clinical outcomes than bacterial ulcers, with no new treatments since the 1960s when topical natamycin was introduced. The randomized controlled Mycotic Ulcer Treatment Trial (MUTT) I showed a benefit of topical natamycin over topical voriconazole for fungal ulcers, particularly among those caused by Fusarium. MUTT II showed that oral voriconazole did not improve outcomes overall, although there may have been some effect among Fusarium ulcers. Given an increase in nonserious adverse events, the authors concluded that they could not recommend oral voriconazole. Viral keratitis differs from bacterial and fungal cases in that it is often recurrent and is common in developed countries. The Herpetic Eye Disease Study (HEDS) I showed a significant benefit of topical corticosteroids and oral acyclovir for stromal keratitis. HEDS II showed that oral acyclovir decreased the recurrence of any type of herpes simplex virus keratitis by approximately half. Future strategies to reduce the morbidity associated with infectious keratitis are likely to be multidimensional, with adjuvant therapies aimed at modifying the immune response to infection holding the greatest potential to improve clinical outcomes.

Multimodal Assessment of Corneal Thinning Using Optical Coherence Tomography, Scheimpflug Imaging, Pachymetry, and Slit-Lamp Examination

PURPOSE

To assess the relationship between corneal thinning measured by clinician-graded slit-lamp examination compared with ultrasound pachymetry (USP), anterior segment optical coherence tomography (AS-OCT), and the Pentacam.

METHODS

Patients with corneal thinning underwent USP, AS-OCT, Pentacam measurements and standardized clinical grading by 2 cornea specialists estimating thinning on slit-lamp examination. Reproducibility of each testing modality was assessed using the intraclass correlation coefficient. Bland-Altman plots were used to determine precision and limits of agreement (LOA) between imaging modalities and clinical grading.

RESULTS

We included 22 patients with corneal thinning secondary to infectious or inflammatory keratitis. Mean percent stromal thinning estimated by grader 1 was 51% (SD 31) and grader 2 was 49% (SD 33). The intraclass correlation coefficient between the masked examiners was 0.95 (95% confidence interval, 0.88-0.98). Graders were more similar to each other than to any other modality with 2% difference and 4.6% of measurements outside the LOA. When measuring the area of maximum thinning, AS-OCT measured approximately 10% thicker than human graders while the Pentacam measured approximately 10% thinner than human graders with 16.7% outside the LOA. USP measured approximately 20% thinner than human graders with 5.6% outside the LOA.

CONCLUSIONS

Trained corneal specialists have a high degree of agreement in location and degree of corneal thinning when measured in a standardized fashion on the same day. Other testing modalities had acceptable reproducibility and agreement with clinical examination and each other, although Scheimpflug imaging fared worse for corneal thinning, particularly in the periphery, than the other modalities.

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.