Adoption of Innovation in Herpes Simplex Virus 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.

Commercial human 3D corneal epithelial equivalents for modeling epithelial infection in herpes keratitis

Herpes stromal keratitis is the leading cause of infectious blindness in the western world. Infection by HSV1 is most common, but VZV and hCMV also infect the cornea. Multiple models of HSV1 corneal infection exist, but none for VZV and hCMV because of their host specificity. Here, we used commercially available 3D human corneal epithelial equivalents (HCEE) to study infection by these herpesviruses. HCEE was infected by HSV-1 and hCMV without requiring scarification and resulted in spreading infections. Spread of HSV-1 infection was rapid, while that of hCMV was slow. In contrast, infections with VZV required damage to the HCEE and did not spread. Acyclovir dramatically reduced replication of HSV-1 in this model. We conclude that highly quality-controlled, readily available HCEE is a useful model to study human-restricted herpesvirus infection of the human corneal epithelium and for screening of antiviral drugs for treating HSK in an 3D model system.

Herpes simplex keratitis: A brief clinical overview

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

Keratic Precipitates: An Overlooked Sign of Microsporidial Stromal Keratitis?

PURPOSE

To elucidate a distinctive clinical feature in cases of microsporidial stromal keratitis (MSK).

METHOD

A retrospective observational study of cases with a histopathological and/or microbiological diagnosis of MSK on corneal biopsy or host corneal button between 2016 and 2022 was conducted.

RESULTS

Eighteen cases with a confirmed histopathological and/or microbiological diagnosis of MSK were detected. Careful review of slit-lamp photographs revealed the presence of pigmented keratic precipitates (KPs) beyond the area of stromal keratitis in five out of eighteen cases (27.7%).

CONCLUSION

The presence of pigmented KPs beyond the area of lesion can alert the clinician to keep microsporidia as a differential cause for stromal keratitis. Management can be tailored accordingly for a better outcome.

Modified host defence peptide GF19 slows TNT-mediated spread of corneal herpes simplex virus serotype I infection

Corneal HSV-1 infections are a leading cause of infectious blindness globally by triggering tissue damage due to the intense inflammation. HSV-1 infections are treated mainly with antiviral drugs that clear the infections but are inefficient as prophylactics. The body produces innate cationic host defence peptides (cHDP), such as the cathelicidin LL37. Various epithelia, including the corneal epithelium, express LL37. cHDPs can cause disintegration of pathogen membranes, stimulate chemokine production, and attract immune cells. Here, we selected GF17, a peptide containing the LL37 fragment with bioactivity but with minimal cytotoxicity, and added two cell-penetrating amino acids to enhance its activity. The resulting GF19 was relatively cell-friendly, inducing only partial activation of antigen presenting immune cells in vitro. We showed that HSV-1 spreads by tunneling nanotubes in cultured human corneal epithelial cells. GF19 given before infection was able to block infection, most likely by blocking viral entry. When cells were sequentially  exposed to viruses and GF19,  the infection was attenuated but not arrested, supporting the contention that the GF19 mode of action was to block viral entry. Encapsulation into silica nanoparticles allowed a more sustained release of GF19, enhancing its activity. GF19 is most likely suitable as a prevention rather than a virucidal treatment.

Frequency and visual outcomes of herpes simplex keratitis in a Kuwaiti tertiary referral center

Background

Herpes simplex virus (HSV), a cause of many ocular pathologies, may affect the corneal epithelium, stroma, or endothelium, with the epithelium as the most frequently affected location. We aimed to determine the frequency and visual outcomes of HSV keratitis over a 1-year period at Farwaniya Hospital, Kuwait.

Methods

This prospective observational case series included patients diagnosed with HSV keratitis who presented to the outpatient or eye casualty department between September 2022 and September 2023. Full history, demographic profile, detailed ocular and slit-lamp examinations, and visual acuity assessments were recorded prior to and after treatment. Baseline corneal sensation was assessed in the four corneal quadrants using the cotton wisp test.

Results

Of the 227 patients who presented with infectious keratitis, 72 (31.7%) were diagnosed with HSV keratitis. The mean (SD) age was 45.86 (16.06) years, and 48 (66.7%) patients were male. The subtypes of HSV keratitis were endotheliitis in 27 (37.5%) patients, dendritic ulcer in 22 (30.6%), stromal keratitis with ulceration in 9 (12.5%) and without ulceration in 8 (11.1%), and geographic ulcer in 6 (8.3%). The mean baseline best-corrected distance visual acuity (BCDVA) differed significantly between the HSV keratitis subtypes (P < 0.001). Most patients (n = 70, 97.2%) had unilateral eye involvement, were treated within 1 - 2 weeks, and demonstrated improved BCDVA. Despite the improvement in BCDVA in all HSV keratitis subtypes, a significant difference in the median BCDVA remained after treatment (P < 0.001). Pairwise comparisons revealed a significantly better BCDVA after treatment in eyes with dendritic epithelial ulcers than in eyes with HSV stromal keratitis with ulceration (P = 0.003) or geographic epithelial ulcers (P = 0.005). After treatment, corneal haze and neovascularization were detected in 54 (75.0%) and 24 (33.3%) patients, respectively.

Conclusions

We detected a substantial frequency of HSV keratitis in one of the governorates of Kuwait, with endotheliitis as the most common manifestation. Timely standard treatment interventions based on valid guidelines resulted in BCDVA improvement in all subtypes of HSV keratitis in our series, indicating the importance of early treatment. However, the BCDVA in eyes with dendritic epithelial ulcers remained substantially better than that in eyes with geographic epithelial ulcers or HSV stromal keratitis with ulceration, signifying the effect of the initial HSV keratitis subtype on visual outcomes. To our knowledge, this is the first study to highlight the frequency of HSV keratitis in a Kuwaiti hospital, and larger-scale research in this region is needed to further understand and manage the condition.

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.

Phylogenetic and Genomic Characterization of Whole Genome Sequences of Ocular Herpes Simplex Virus Type 1 Isolates Identifies Possible Virulence Determinants in Humans

Purpose

There are limited data on the prevalence and genetic diversity of herpes simplex virus type 1 (HSV-1) virulence genes in ocular isolates. Here, we sequenced 36 HSV-1 ocular isolates, collected by the Bascom Palmer Eye Institute, a university-based eye hospital, from three different ocular anatomical sites (conjunctiva, cornea, and eyelid) and carried out a genomic and phylogenetic analyses.

Methods

The PacBio Sequel II long read platform was used for genome sequencing. Phylogenetic analysis and genomic analysis were performed to help better understand genetic variability among common virulence genes in ocular herpetic disease.

Results

A phylogenetic network generated using the genome sequences of the 36 Bascom Palmer ocular isolates, plus 174 additional strains showed that ocular isolates do not group together phylogenetically. Analysis of the thymidine kinase and DNA polymerase protein sequences from the Bascom Palmer isolates showed multiple novel single nucleotide polymorphisms, but only one, BP-K14 encoded a known thymidine kinase acyclovir resistance mutation. An analysis of the multiple sequence alignment comprising the 51 total ocular isolates versus 159 nonocular strains detected several possible single nucleotide polymorphisms in HSV-1 genes that were found significantly more often in the ocular isolates. These genes included UL6, gM, VP19c, VHS, gC, VP11/12, and gG.

Conclusions

There does not seem to be a specific genetic feature of viruses causing ocular infection. The identification of novel and common recurrent polymorphisms may help to understand the drivers of herpetic pathogenicity and specific factors that may influence the virulence of ocular disease.

Herpes simplex virus, varicella-zoster virus and cytomegalovirus keratitis: Facts for the clinician

Keratitis due to Herpes simplex virus (HSK), Varicella-Zoster virus (VZK) and Cytomegalovirus remains a frequent source of concern for many ophthalmologists. They are a frequent cause of emergency consultations at eye care centers and carry the risk of permanent loss of visual acuity or visual quality and/or chronic neurotrophic keratitis, resulting in a significant decrease in the quality of life. HSK and VZK can affect the corneal epithelium, stroma, or endothelium or a combination of layers. In contrast, most cases of CMV keratitis present as isolated endothelitis (CMVE), a clinical entity that has been described within the last 2 decades. These three types of viral keratitis are characterized by a high frequency of recurrences and each new episode increases the risk of sequelae. Hence, ophthalmologists must adapt the treatment to the clinical presentation of each recurrent episode in order to mitigate the immediate consequences of viral replication and the immune response on corneal transparency. In patients with frequent recurrences, preventive long-term antiviral treatment is strongly recommended. However, in some rare cases, continuous exposure to antivirals may promote the emergence of resistant viral strains, which can be difficult to manage. In the future, the introduction of new antiviral drugs, with differing modes of action compared to current medical therapy, could be an alternative until a truly effective preventive solution, such as a vaccine, is available.

Urgent unmet needs in the care of bacterial keratitis: An evidence-based synthesis

Bacterial corneal infections, or bacterial keratitis (BK), are ophthalmic emergencies that frequently lead to irreversible visual impairment. Though increasingly recognized as a major cause of global blindness, modern paradigms of evidence-based care in BK have remained at a diagnostic and therapeutic impasse for over half a century. Current standards of management - based on the collection of corneal cultures and the application of broad-spectrum topical antibiotics - are beset by important yet widely underrecognized limitations, including approximately 30% of all patients who will develop moderate to severe vision loss in the affected eye. Though recent advances have involved a more clearly defined role for adjunctive topical corticosteroids, and novel therapies such as corneal crosslinking, overall progress to improve patient and population-based outcomes remains incommensurate to the chronic morbidity caused by this disease. Recognizing that the care of BK is guided by the clinical axiom, "time equals vision", this chapter offers an evidence-based synthesis for the clinical management of these infections, underscoring critical unmet needs in disease prevention, diagnosis, and treatment.

Platinum-Nucleos(t)ide Compounds as Possible Antimetabolites for Antitumor/Antiviral Therapy: Properties and Perspectives

Nucleoside analogues (NAs) are a family of compounds which include a variety of purine and pyrimidine derivatives, widely used as anticancer and antiviral agents. For their ability to compete with physiological nucleosides, NAs act as antimetabolites exerting their activity by interfering with the synthesis of nucleic acids. Much progress in the comprehension of their molecular mechanisms has been made, including providing new strategies for potentiating anticancer/antiviral activity. Among these strategies, new platinum-NAs showing a good potential to improve the therapeutic indices of NAs have been synthesized and studied. This short review aims to describe the properties and future perspectives of platinum-NAs, proposing these complexes as a new class of antimetabolites.

A Patient With Recurrent Immune Stromal Keratitis and Adherence Challenges

Background

Herpes simplex keratitis (HSK) is a common yet potentially blinding condition caused by a primary or reactivated herpetic infection of the cornea. Immune stromal keratitis (ISK), a type of HSK, is classified by a cellular and neovascularization infiltration of the cornea, and patients with ISK may experience low-grade chronic keratitis for years.

Case Presentation

A 52-year-old man presented to the eye clinic complaining of a watery and itchy right eye with mildly blurred vision. With consultation from a corneal specialist, the patient was given the presumptive diagnosis of ISK in the right eye based on the unilateral corneal presentation and lack of corneal sensitivity.

Conclusions

ISK presents unilaterally with decreased or absent corneal sensitivity and nonspecific symptoms. It should be at the top of the list in the differential diagnosis in any patient with unilateral corneal edema, opacification, or neovascularization, and the patient should be started on oral antiviral therapy.

Ophthalmic Solutions with a Broad Antiviral Action: Evaluation of Their Potential against Ocular Herpetic Infections

HSV-1 can be associated with severe and recurrent eye infections characterized by a strong inflammatory response that leads to blepharoconjunctivitis, epithelial and stromal keratitis, and retinal necrosis. The incidence of HSV-1 keratitis is 1.5 million every year worldwide, including more than 40,000 new cases exhibiting serious visual failures. Generally, the therapy uses antiviral drugs to promote healing; however, there are currently no compounds that are able to completely eradicate the virus. In addition, the phenomenon of resistance is rapidly spreading among HSV-1 strains, creating mutants developing resistance to the common antiviral drugs; therefore, deep research on this issue is warranted. The efficacy of different ophthalmic solutions already on the market was evaluated for reducing HSV-1 infection. Different plaque assays were set up on epithelial cells, revealing that two ophthalmic solutions were able to inhibit viral replication in the early stages of infection. The data were further confirmed by molecular tests analyzing the expression levels of the principal genes involved in HSV-1 infection, and a strong reduction was observed after only 1 min of eye-drop treatment. Collectively, these results suggested the use of ophthalmic solutions as potential antiviral options for the treatment of ocular herpetic infection.

Clinical course and treatment of archipelago keratitis: a Herpesviridae keratitis subtype

PURPOSE

Archipelago keratitis (ApK) is a subtype of Herpesviridae stromal keratitis that consists of subepithelial nummular inflammatory infiltrates arranged in a radial centripetal pattern. This rare and poorly described form is not often recognised early. We report the first large series of ApK, with an analysis of clinical settings at presentation, evolution of the disease with time and a description of factors associated with recurrence.

METHODS

The clinical records of 82 patients (83 eyes) with a diagnosis of ApK between 2011 and 2021 in two centres were reviewed.

RESULTS

The median age of the 82 patients at referral was 37±28 years. ApK was unilateral in all but one case. A total of 76% of patients had at least one second diagnostic criteria suggesting a herpetic aetiology. Overall, 44 (53%) eyes exhibited least one recurrence after a median of 12 months. Recurrence was frequently associated with neovascularisation (HR 2.1, 95% CI 1.1 to 3.9; p=0.02) and tapering corticosteroids (HR 3.5, 95% CI 1.8 to 7.1; p<0.01) or valaciclovir use (HR=2.3, 95% CI 1.2 to 4.6; p=0.01). Antiviral treatment was used in all patients, whereas local anti-inflammatory drugs such as corticosteroids and/or ciclosporin were used in 73 (88%) cases.

CONCLUSION

ApK is a Herpesviridae stromal keratitis that is typically unilateral in presentation and features a high risk of recurrence. Combined treatment with antiviral and anti-inflammatory drugs are usually required over the long term. Topical ciclosporin can be useful as a corticosteroid-sparing treatment.

Optical coherence tomography angiography in herpetic leucoma

BACKGROUND

Herpes simplex virus (HSV) keratitis remains a leading infectious cause of blindness worldwide. Although all forms of HSV keratitis are commonly recurrent, the risk is greatest in stromal keratitis, which is the most likely to result in corneal scarring, thinning, and neovascularization. Recent studies showed the ability of Optical Coherence Tomography Angiography (OCTA) to detect and study vascular abnormalities in the anterior segment, including abnormal corneal vessels. This study intends to investigate the potential of OCTA device to image and describe quantitatively the vascularization in eyes diagnosed with herpetic leucoma and to discuss and review the usefulness of this technique in this pathology.

METHODS

A Cross-sectional study was made, including 17 eyes of 15 patients with leucoma secondary to herpetic keratitis. All eyes underwent anterior segment Slit-Lamp photography (SLP), and OCTA with en-face, b-scans and c-scans imaging. The vessel density (VD) was analyzed in the inferior, nasal and temporal corneal margin in all patients, and in the central area, in eyes with central corneal neovascularization (CoNV). The measurements were calculated after binarization with ImageJ software, using OCTA scans with 6 × 6 mm in a depth of 800 μm.

RESULTS

Patients included had a mean age 53.267 ± 21.542 (years ± SD). The mean total vessel area was 50.907% ± 3.435%. VD was higher in the nasal quadrant (51.156% ± 4.276%) but there were no significant differences between the three analyzed areas (p = 0.940). OCTA was able to identify abnormal vessels when SLP apparently showed no abnormal vessels; OCTA was able to distinguish between larger and smaller vessels even in central cornea; OCTA scans allowed the investigation of several corneal planes and the relation of them with clinical findings.

CONCLUSIONS

OCTA can be useful in both qualitative and quantitative follow-up of patients and may become a non-invasive alternative to objectively monitor treatment response in eyes with corneal vascularization due to herpetic infection.

Role of Intravenous Acyclovir in Treatment of Herpes Simplex Virus Stromal Keratitis with Ulceration: A Review of 2 Cases

BACKGROUND Herpes simplex virus (HSV) stromal keratitis with ulceration is one of the most serious forms of herpes corneal infection and is one of the most difficult conditions in terms of clinical management. We assessed the efficacy of intravenous acyclovir in the treatment of this condition. CASE REPORT Two cases of HSV stromal keratitis with ulceration were reported in terms of clinical presentation, investigation, treatment, and outcome.Diagnosis was confirmed by polymerase chain reaction (PCR) analysis. PCR testing of corneal scraping samples identified HSV-1 in the first patient and HSV-2 in the second patient. The first patient initially presented with herpes geographic epithelial keratitis and progressed to HSV stromal keratitis with ulceration during treatment with a prophylactic dose of oral acyclovir. Despite oral acyclovir therapy, the cornea lesion continued to worsen. The treatment was switched to intravenous acyclovir. The stromal infiltration gradually improved, and the epithelial defect closed. The second patient, who had undergone penetrating keratoplasty for 13 years, presented with extensive corneal infiltration and corneal melting. The laboratory work-up was positive for HSV-2, and intravenous acyclovir was prescribed. The patient's corneal infiltration improved, but a persistent epithelial defect was present. Then, 100% autologous serum was used until the epithelial defect closed. Prophylactic treatment with oral acyclovir was prescribed to both patients to prevent disease recurrence. CONCLUSIONS Intravenous acyclovir might be considered as an alternative treatment for patients with HSV stromal keratitis with ulceration who do not respond to oral acyclovir or those with an extensive infection on a corneal graft.