Ocular surgery after herpes simplex and herpes zoster keratitis

Control of HSV-1 Infection: Directions for the Development of CRISPR/Cas-Based Therapeutics and Diagnostics

It is estimated that nearly all individuals have been infected with herpesviruses, with herpes simplex virus type 1 (HSV-1) representing the most prevalent virus. In most cases, HSV-1 causes non-life-threatening skin damage in adults. However, in patients with compromised immune systems, it can cause serious diseases, including death. The situation is further complicated by the emergence of strains that are resistant to both traditional and novel antiviral drugs. It is, therefore, imperative that new methods of combating HSV-1 and other herpesviruses be developed without delay. CRISPR/Cas systems may prove an effective means of controlling herpesvirus infections. This review presents the current understanding of the underlying molecular mechanisms of HSV-1 infection and discusses four potential applications of CRISPR/Cas systems in the fight against HSV-1 infections. These include the search for viral and cellular genes that may serve as effective targets, the optimization of anti-HSV-1 activity of CRISPR/Cas systems in vivo, the development of CRISPR/Cas-based HSV-1 diagnostics, and the validation of HSV-1 drug resistance mutations.

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.

Analysis of clinical characteristics and factors influencing herpes simplex virus keratitis

Objective

To investigate the clinical characteristics and factors associated with herpes simplex virus keratitis.

Methods

Patients with herpes simplex virus keratitis who came to our hospital from January 2018 to June 2022 were selected and divided into a good prognosis group and a poor prognosis group according to their prognosis. The clinical data of the two groups were compared, and univariate/multivariate logistic regression was used to analyze the factors influencing the poor prognosis of herpes simplex virus keratitis.

Results

A one-way analysis of variance showed that, compared with the good prognosis group, the poor prognosis group had more elderly patients and a longer course of disease, and the difference was statistically significant (p < 0.05). There were significant differences in the types of patients between the two groups (p < 0.05). Univariate logistic regression analysis also showed that age (≥65 years) (OR: 1.557, 95%CI: 1.081-2.183, p < 0.05), course of disease (> 7 months) (OR: 1.303, 95%CI: 1.003-1.829, p < 0.05), epithelial type (OR: 2.321, 95%CI: 1.198-4.321, p < 0.05), and stromal type (OR: 2.536, 95%CI: 1.672-3.871, p < 0.05) were risk factors for poor prognosis. Multivariate logistic regression analysis showed that age (≥65 years) (OR: 1.656, 95%CI: 1.168-2.357, p < 0.05) and course of disease (> 7 months) (OR: 1.461, 95%CI: 1.031-2.001, p < 0.05) were independent risk factors for the prognosis of herpes simplex keratitis.

Conclusion

The clinical symptoms of herpes simplex virus keratitis include corneal opacity, corneal posterior elastic layer folds, corneal infiltration, posterior corneal mass, corneal edema, and ocular pain. Age and course of disease are important factors in the prognosis of herpes simplex virus keratitis.

In vivo CRISPR gene editing in patients with herpetic stromal keratitis

In vivo CRISPR gene therapy holds large clinical potential, but the safety and efficacy remain largely unknown. Here, we injected a single dose of herpes simplex virus 1 (HSV-1)-targeting CRISPR formulation in the cornea of three patients with severe refractory herpetic stromal keratitis (HSK) during corneal transplantation. Our study is an investigator-initiated, open-label, single-arm, non-randomized interventional trial at a single center (NCT04560790). We found neither detectable CRISPR-induced off-target cleavages by GUIDE-seq nor systemic adverse events for 18 months on average in all three patients. The HSV-1 remained undetectable during the study. Our preliminary clinical results suggest that in vivo gene editing targeting the HSV-1 genome holds acceptable safety as a potential therapy for HSK.

Combined versus sequential penetrating keratoplasty and cataract surgery for herpes simplex keratitis: a retrospective study

Purpose

To compare the surgical outcomes of combined penetrating keratoplasty (PK) and cataract surgery with those of sequential surgery (cataract surgery after PK) for herpes simplex keratitis (HSK).

Methods

The medical records of consecutive patients diagnosed with HSK who underwent combined or sequential PK and cataract surgery in active and stable stages between June 2015 and June 2022 were reviewed retrospectively. Complications, graft survival, endothelial cell density (ECD), and final BCVA were compared and analyzed between both surgical methods in each stage.

Results

A total of 171 eyes of 171 patients were enrolled, including active stage (69 combined, 46 sequential) and stable stage (34 combined, 22 sequential). The average follow up was 24.2 ± 15.8 months (range, 3 months - 48 months). The final BCVA had obvious improvement and the postoperative ECD was not different in combined and sequential groups of each stage. In sequential group of active stage, 66.7% of persistent epithelial defects and 50% of HSK recurrence occurred within 3 months after cataract surgery; nevertheless, compared to that in sequential group, capsular rupture (p = 0.021), persistent epithelial defects (p = 0.027), and HSK recurrence (p = 0.035) occurred more frequently in combined group, leading to a lower graft survival rate (p = 0.045); at the last visit, 46.4 and 67.4% of grafts remained clear in combined and sequential groups, respectively. By contrary, 82.4 and 50.0% of grafts remained clear in stable stages of combined and sequential groups at the last visit, respectively, and a higher graft survival rate was observed in combined group (p = 0.030).

Conclusion

Although the postoperative ECD is not different between two surgical groups in each stage, sequential surgery in active stage of HSK seems to have advantages in less complications and higher graft survival rate, whereas combined surgery in stable stage has a better outcome than that in sequential surgery.

Cataract surgery in herpes simplex virus ocular disease

PURPOSE

To investigate the outcomes and complications associated with cataract surgery in eyes with herpes simplex virus (HSV)-related anterior segment ocular disease.

SETTING

Public tertiary center in Auckland, New Zealand.

DESIGN

Retrospective observational cohort study.

METHODS

Clinical records of patients diagnosed with HSV-related keratitis and/or anterior uveitis who underwent subsequent cataract surgery in the affected eye were reviewed. Main outcomes measured were visual outcome, complications, and recurrence.

RESULTS

37 eyes of 37 patients were included. Intraoperative complications occurred in 1 patient (2.7%) with iris prolapse. Keratitis or uveitis recurred postoperatively in 17 patients (45.9%) 8 patients (22.5%); 22.5% experienced recurrences in the first year postoperatively. 1 case (2.7%) of postoperative cystoid macular edema and 1 (2.7%) postoperative endophthalmitis occurred. Corrected distance visual acuity at 3 months was >20/50 in 21 patients (70.0%), 20/50 to 20/200 in 4 patients (12.9%), and ≤20/200 in 6 patients (19.4%). Vision improved in 26 eyes (83.9%) and worsened in only 1 eye (3.2%). Risk for recurrent inflammation was associated with a greater number of recurrences prior to surgery (hazard rate [HR] 1.31), time quiescent prior to surgery (HR 0.48), and iris transillumination defect at preoperative assessment (HR 57.66).

CONCLUSIONS

Cataract surgery in eyes with previous HSV disease may improve visual acuity for most of the eyes but, overall, carries a guarded prognosis, particularly in eyes with corneal scarring. There is a significant risk for recurrent inflammation in the first year postoperatively. If possible, surgeons should ensure a period of disease quiescence prior to surgery.

Evidence in the prevention of the recurrence of herpes simplex and herpes zoster keratitis after eye surgery

OBJECTIVE

Herpetic keratitis, either due to herpes simplex keratitis (HSK) or herpes zoster ophthalmicus (HZO), can recur after eye surgery.º Prophylaxis is postulated as necessary to avoid it. The objective of this study was to review the scientific evidence on the preventive methods used in the perioperative period in patients previously affected by HSK/HZO.

METHODS

An exhaustive search was carried out in the PubMed and Web of Science databases to identify relevant articles on prophylaxis and risk of recurrence of HSK/HZO in patients undergoing eye surgery up to 31 December 2019.

RESULTS

There is strong evidence that oral prophylaxis should be recommended after penetrating keratoplasty in patients who have previously had HSK/HZO. For other types of surgery, the evidence is less compelling. However, a latent period of inactivity should be considered between disease and oral prophylaxis.

CONCLUSIONS

Penetrating and lamellar keratoplasty, corneal crosslinking, cataract surgery, and photorefractive and phototherapeutic surgery cause an alteration of the subbasal nerve plexus of the cornea. Due to surgical trauma, as well as the modulation of the ocular immune response caused by steroids applied in the postoperative period, it is possible to induce the reactivation of HSK/HZO, which is common in some cases. Within this article, we discuss the available evidence for HSK/HZO prophylaxis in eye surgery. Further studies are necessary to define the real risk of HSK/HZO recurrence after ocular surgeries, particularly in cataract surgery, and to confirm the efficacy of perioperative prophylaxis with anti-HSK/HZO antivirals.

Implantation of an Artificial Endothelial Layer for Treatment of Chronic Corneal Edema

PURPOSE

The purpose of this study was to describe a novel device that may serve as an alternative to Descemet membrane endothelial keratoplasty (DMEK) for the treatment of chronic corneal edema.

METHODS

The EndoArt (EyeYon Medical, Israel) is a flexible, 50-μm thin artificial endothelial layer that matches the cornea's posterior curvature and functions as a fluid barrier at the posterior stroma, replacing the diseased endothelium. Similar to a DMEK approach, it is implanted into the anterior chamber, carefully positioned on the posterior stroma, and secured using an air-gas mixture. Two patients with chronic corneal edema resulting from endothelial decompensation underwent implantation of the new artificial lamella.

RESULTS

In patient 1, the central corneal thickness (CCT) decreased from 730 μm preoperatively to 593 μm at 1 day postoperatively. In patient 2, the CCT decreased from 761 μm preoperatively to 487 μm at 1 day postoperatively. Both patients reported high satisfaction and an overall brighter visual quality. Although dislocation of the lamella occurred in both cases, the CCT was promptly restored after a repositioning procedure and remained stable at the 17-month follow-up (CCT of 526 and 457 μm for patients 1 and 2, respectively). In contrast to DMEK donor tissue, the artificial lamella is sufficiently robust to allow easy intraocular manipulation without the risk of damaging the implant. It is easily removable and does not require any immunosuppressive treatment because of its nonbiological nature.

CONCLUSIONS

Implantation of the EndoArt led to rapid corneal deturgescence and CCT restoration, presenting a possible option for patients with chronic corneal edema.

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.