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.

Improving polymerase chain reaction diagnostic rates for herpes simplex keratitis: results of a pilot study

Background

Laboratory confirmation is crucial for diagnosis and management of herpes simplex virus (HSV) keratitis. However, the sensitivity of polymerase chain reaction (PCR) in keratitis is low (25%) compared with that of mucocutaneous disease (75%). We developed an educational intervention aimed at improving the diagnostic yield of PCR.

Methods

The medical records of keratitis cases seen at the emergency department of a London tertiary ophthalmic referral hospital over two distinct periods, before and after an educational program on swab technique, were reviewed retrospectively.

Results

A total of 252 HSV cases were included. Increases in the laboratory-confirmed diagnosis of HSV-1 were observed, in both first presentations (11.1%-57.7%) and recurrent cases (20%-57.6%). The rate of positive HSV-1 PCR in eyes with an epithelial defect increased from 19% pre-intervention to 62% post intervention. Notably, 3% were positive for varicella zoster virus DNA, and there was a single case of Acanthamoeba keratitis.

Conclusion

Our results suggest that, with proper swabbing technique, PCR may be more sensitive than previously reported.

Diagnostic performance of real-time quantitative PCR in tear samples in various subtypes of herpes simplex keratitis

Diagnosis of herpes simplex keratitis (HSK) is mostly based on clinical findings, yet biological confirmation supports management of challenging cases. This study evaluated the place of real-time quantitative PCR (RT-qPCR) on tear samplings in the management of HSK. Clinical records of patients who underwent tear sampling tested by RT-qPCR for herpes simplex virus type 1 for an acute episode of corneal inflammation or defect between January 2013 and December 2021 were retrospectively reviewed, and results were compared to clinical diagnosis (i.e., HSK or not) based on biomicroscopic findings and medical history. Of 465 tested tear samples from 364 patients, a clinical diagnosis of active (ongoing) HSK was recorded in 240 cases, among which 76 were RT-qPCR positive (global sensitivity of 31.6%, specificity of 99.5%). Sensitivity of RT-qPCR was higher in epithelial (97.4%) and stromal keratitis with ulceration (48.7%), compared to other types of HSK (23.5% in keratouveitis, 13.6% in endotheliitis, 11.1% in postherpetic neurotrophic keratopathy, and 8.1% in stromal keratitis without ulceration). The highest viral loads were detected from epithelial and stromal keratitis with ulceration, while in HSK with no epithelial involvement, the viral load detected was 196-fold lower, on average. The proportion of clinically characterized HSK patients with negative tear samples was higher in patients receiving antiviral treatment (P < 0.0001). RT-qPCR, performed on tear samples, can help in confirming diagnosis in case of presumed HSK, including clinical forms with no obvious epithelial involvement. The sensitivity of tear sampling is much higher whenever epithelial keratitis is present.

Keep Eyes on COVID-19: Ophthalmic Symptoms and Potential Transmission of SARS-CoV-2 through the Oculus

In December 2019, a new coronavirus disease 2019 (COVID-19) emerged and rapidly spread globally, posing a worldwide health emergency. The pathogen causing this pandemic was identified as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). It is well known that SARS-CoV-2 transmits via respiratory droplets and close contact with infected individuals or contaminated items. In addition to these two major transmission routes, other modes of transmission have not been confirmed. Considering that some COVID-19 patients have presented with ocular discomforts and positive SARS-CoV-2 RNA in ocular surfaces, as well as the discovery of the SARS-CoV-2 receptors, angiotensin-converting enzyme 2, and transmembrane protease, serine 2, in the oculus, the ocular surface is now thought to be a possible alternative route of SARS-CoV-2 transmission and a replication site. This review summarizes the evidence connecting COVID-19 with ocular tissues, ocular symptoms during SARS-CoV-2 infection, the potential role of the conjunctiva in SARS-CoV-2 transmission, and the physiopathological mechanisms. Appropriate precautions in ophthalmology departments, including innovative complete and effective patient management plans, protective personal equipment, hand hygiene, and strict personal distance intervals, are essential to effectively minimize the spread of SARS-CoV-2 and control the pandemic.

Seroprevalence and characterisation of herpes simplex virus from human immunodeficiency virus in samples collected from the North-West and KwaZulu-Natal Provinces: a retrospective study

Background: Herpes simplex viruses (HSVs) are highly pervasive and show a strong synergistic interaction with human immunodeficiency virus (HIV). High prevalence of HSV type 1 (HSV-1) has been reported in Africa with a prevalence rate of 20-80% in women and 10-50% in men. Studies on the prevalence of HSV in South Africa are few considering the rate of HIV infection in the country. Our focus was to determine the molecular prevalence of HSV-DNA in HIV-1 sera. Methods: In total, 44 convenience samples were screened for HSV and HIV-1 using the highly sensitive enzyme-linked immunosorbent assay (ELISA). The ELISA positive samples were characterized using polymerase chain reaction (PCR) to confirm the positivity of both viruses and to further differentiate HSV into HSV-1 and -2. Thereafter, the samples were analysed for relatedness using phylogenetic analysis. Results: Of 44 samples, 36 (81.8%) were positive for HIV-1, while 35 (79.5%) were positive for HSV when screened with ELISA kits. The results of PCR with type specific primers showed that 4/35 (11.4%) samples were specific for HSV-1 while 30/35 (85.7%) were specific for HSV-2. Statistical analysis performed using chi-squared goodness-of-fit test showed that there is a significant relationship between HSV-2 and HIV-1 transmission. Conclusions: High prevalence of HSV-2 recorded in HIV-1 sera corroborate with similar studies conducted within different cohorts in the continent. SPSS Pearson's chi-squared test established that there is a significant relationship between HSV-2 and HIV-1 transmission.

A systematic review on advances in diagnostics for herpes simplex keratitis

Herpes simplex keratitis (HSK) is a significant cause of vision impairment worldwide. Currently, there are no set diagnostic criteria, and popular diagnostic methods, including clinical examination of the eye via slit lamp examination, could lead to false-negatives and misdiagnoses. Molecular testing with polymerase chain reaction (PCR) may lack concordance with clinical findings, posing a great challenge to ophthalmologists. We evaluate recent studies on techniques for the diagnosis of HSK. We included a total of 23 studies published between 2010 and 2020 in English on diagnostic techniques, including in vivo confocal microscopy, polymerase PCR testing, protein detection in tear film with enzyme-linked immunosorbent assay, and various other protein assays. Although PCR has been widely used as one of the current diagnostic methods for HSK, most studies evaluated its efficacy after including alterations to its normal protocol. Tear sample analysis was performed using multiple tools, although corneal scrapings demonstrated a higher positive detection rate. Diagnostic tools identified were able to detect HSK with varying accuracy. Newer diagnostic techniques like multiplex dot hybridization assay and immunochromatographic assays may be considered as the point-of-care preliminary diagnostic tools. More reliable results may be generated by developing a standardized diagnostic protocol.

Ocular manifestations of dermatological diseases part I: infectious and inflammatory disorders

Skin and eyes share a common embryological origin from the embryonic surface ectoderm. Ocular manifestations are one of the most important and common associations of dermatological diseases. Currently, there are few comprehensive reviews of the ocular manifestations of dermatological diseases. We have reviewed more than 40 published articles related to the ocular manifestations of the most important dermatological diseases. The search included Pubmed, Google Scholar, and Cochrane databases from 2014 to 2019. This review was divided into three parts including infections, inflammatory, genetics, connective tissue, autoimmune, neoplasms, and drug-related disorders. We excluded metabolic, endocrine, and nutrition-related dermatological diseases. The relationship of ocular manifestations and dermatological diseases is important to recognize for appropriate management since many dermatological diseases can manifest initially with ocular findings. In this part, we summarized the most common and significant ocular findings in infectious and inflammatory dermatological disorders with appropriate referral recommendations to ophthalmology.

Atypical herpes simplex keratitis: frequency, clinical presentations and treatment results

AIMS

To determine herpes simplex virus (HSV) DNA positivity in corneal scraping samples obtained from patients with microbial keratitis whose findings were not specific for HSV keratitis and to evaluate these particular cases with respect to clinical features and antiviral treatment results.

METHODS

Records of patients with microbial keratitis treated in a tertiary eye care hospital within the 3-year period were evaluated retrospectively. Real-time polymerase chain reaction (PCR) was used to identify HSV DNA. Smear slides were evaluated by light microscopy. Patients with typical presentations and histories of HSV keratitis were excluded.

RESULTS

Two hundred and seventy-six eyes of 276 patients were included in the study. HSV-1 DNA was detected in 25 eyes (9%). In these 25 eyes, the initial diagnosis was fungal or bacterial keratitis. The mean symptom duration was 20 ± 14 days (2-60 days). The risk factors were ocular surgery (20%), blepharitis (16%), trauma (8%) and contact lens wear (4%); however, the majority of patients did not have any specific cause for keratitis (52%). Clinical features were variable and not typical for any particular etiology. Culture and microscopic examinations revealed bacteria and/or fungi in 6 patients in addition to herpes infection. Antiviral treatment was successful in 72% of patients.

CONCLUSION

Herpetic corneal infections can present without typical dendritic or geographic ulcers and may be masked by other infections. Real-time PCR is a useful method for rapid and definitive diagnosis. HSV infection should be considered for microbial keratitis without specific risk factors, with negative culture results and poor response to antimicrobial agents.