Clinical Pattern And Visual Impairment Associated With Herpes Simplex Keratitis

Tear metabolomics reveals novel potential biomarkers in epithelial herpes simplex keratitis

BACKGROUND

Herpes simplex keratitis (HSK) is a recurrent inflammatory disease of cornea primarily initiated by type I herpes simplex virus infection of corneal epithelium. However, early diagnosis of HSK remains challenging due to the lack of specific biomarkers. This study aims to identify biomarkers for HSK through tear metabolomics analysis between HSK and healthy individuals.

METHODS

We conducted a cross-sectional study enrolling 33 participants. Tear samples were collected from one eye of 18 HSK patients and 15 healthy volunteers using Schirmer-strips. Tear metabolomic profiling was performed using high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS). Metabolites were quantified and matched against entries in the human metabolome database (HMDB) and small molecule pathway database (SMPDB) to identify metabolites and metabolic pathways, respectively. Metabolic differences between HSK and control group were determined using multivariate statistical analysis.

RESULTS

A total of 329 metabolites were identified, of which 18 were significantly altered in HSK patients. Notably, 12 metabolites were significantly increased, and 6 were significantly decreased in HSK patients. The changed metabolites were enriched in these pathways: arginine and proline metabolism, phospholipid biosynthesis, alpha linolenic acid and linoleic acid metabolism, retinol metabolism. To assess the potential utility of tear biomarkers, a predictive model was developed combining 4 metabolites (AUC = 0.998 [95%CI: 0.975, 1]): D-proline, linoelaidic acid, plantagonine, and phosphorylcholine.

CONCLUSIONS

Our study establishes that HSK has a distinctive metabolomic profile, with 4 key elements maybe emerging as potential biomarkers for diagnostic purposes. These findings may provide novel insights into early and rapid diagnosis of HSK.

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

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

Clinical and Demographic Characteristics of Herpetic Keratitis Patients-Tertiary Centre Experience

Background and Objectives: Herpes simplex keratitis (HSK) is the leading infectious cause of corneal damage and associated loss of visual acuity. Because of its frequent recurrence, it represents a major health problem; thus, timely and accurate diagnosis is the key to successful treatment. To enable this, we aimed to determine HSK patients' demographic and clinical features. Materials and Methods: This prospective study included 55 patients diagnosed with HSK between March 2019 and August 2022 at the Department of Ophthalmology, Clinical Hospital Rijeka. Results: We found that HSK is most prevalent in the elderly, with 72.73% of patients older than 60. The most common HSK types were dendritic (HSK-D; 43.64%) and stromal with epithelial ulceration (HSK-SEU 23.64%). HSK recurrences occurred in 65.45% of patients, with most having two to five recurrences (55.56%). Visual acuity at presentation (65.5%) and after treatment (50.9%) was mostly in the 20/50 range. The longest period until the disease symptoms were resolved was in the group with stromal HSK without epithelial ulceration (HSK-SnEU), for which symptoms lasted more than 11 weeks in 87.5% of patients. The overall incidence of HSK-related complications was high (85.45%), with 76.4% of patients having corneal scarring. The average time from symptom to treatment was 15.78 days. Interestingly, we observed a strong seasonality in the incidence of HSK, which was most prevalent in the colder months, with 63.6% of cases occurring between October and March. Conclusions: To the best of our knowledge, this is the first prospective study in Croatia, and one of the few in Europe, to describe the demographic and clinical features of HSK patients. We found that HSK is most common in the elderly population, with its dendritic form as a clinical presentation. We have shown that HSK is prone to recurrence and secondary complications, with a worryingly long time between symptom and treatment, indicating the need for diagnostic testing in routine practice.

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.

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.

Acute-Onset Postoperative Herpetic Endophthalmitis: A Case Report

Herpes simplex virus uveitis without corneal reactivation is more frequent than previously thought. Although herpes simplex virus has been implicated as a cause of postoperative uveitis and endophthalmitis, it has not been reported as a cause of acute postoperative endophthalmitis within the early postoperative period, specifically within one week following cataract extraction. A 55-year-old man with vascularized irregular central disc-shaped stromal corneal opacity with complicated cataracts underwent cataract surgery. Intraoperatively, there was posterior capsular rent, requiring anterior vitrectomy. On postoperative day three, the patient had an increase in inflammation in the anterior chamber (grade 4+) with marked vitreous haze (grade 4). Vitreous taps were negative for bacteria and fungi, and despite intravitreal injections of vancomycin and ceftazidime, the patient had worsening of inflammation with increasing exudates and the appearance of the fibrinous membrane in the anterior chamber. Polymerase chain reaction (PCR) of aqueous and vitreous samples at this point of time yielded positive serology for herpes viral DNA, and the patient was started on oral valacyclovir. The ocular inflammation resolved soon after switching to oral valacyclovir. Typical acute postoperative endophthalmitis starts two to seven days after surgery, and the most common isolate in vitreous biopsies is coagulase-negative staphylococci. We report a rare case of acute-onset herpetic endophthalmitis presenting within 72 hours following cataract surgery for a complicated cataract in a patient with a history of pre-existing healed viral keratitis. Our case highlights that a suspicion of viral endophthalmitis should be kept in mind as a cause of acute-onset post-cataract surgery endophthalmitis, especially in cases of surgery that fail to yield a positive result on Gram's stain, culture or PCR for bacteria and fungi.

Stromal Keratitis among Herpes Simplex Keratitis Patients in a Tertiary Eye Hospital: A Descriptive Cross-sectional Study

Introduction

The manifestations of herpes simplex virus keratitis range from epithelial keratitis to vision-threatening stromal keratitis. There are limited studies done on our part regarding stromal keratitis. The aim of the study was to find out the prevalence of stromal keratitis among herpes simples keratitis patients in a tertiary eye hospital.

Methods

This descriptive cross-sectional study was conducted among patients who presented with herpes simplex virus keratitis in a tertiary eye hospital between 1 January 2020 to 28 February 2022. Ethical clearance was taken from Ethical Review Board (Reference number: 1/2079/80). Data was collected from hospital records which was reviewed and visual acuity at presentation and at one-month follow-up, clinical details on examination were recorded and, diagnosis of the stage of disease given in the case record was noted. Convenience sampling was used. Point estimate and 95% Confidence Interval were calculated.

Results

Among 112 Herpes simplex keratitis patients, the prevalence of stromal keratitis was 38 (33.93%) (25.16-42.70, 95% Confidence Interval).

Conclusions

The prevalence of stromal keratitis among patients of herpes simplex keratitis was similar to studies conducted in similar settings.

Keywords

herpes simplex keratitis; keratitis; prevalence.