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Herpes simplex dendritic keratitis — Clinical Guidelines

Overview

Herpes simplex dendritic keratitis (HSDK) is an inflammatory condition of the cornea characterized by the infiltration of dendritic cells, often secondary to herpes simplex virus (HSV) infection. This condition manifests as painful, multifocal, dendritic ulcerations on the corneal epithelium, which can lead to significant visual impairment if not promptly treated. Primarily affecting individuals with a history of HSV infection, it can occur in immunocompetent and immunocompromised patients alike. Early recognition and management are crucial in preventing corneal scarring and potential blindness, making accurate diagnosis and timely intervention essential in ophthalmic practice 1 8.

Pathophysiology

HSDK typically arises from reactivation of latent HSV-1 or, less commonly, HSV-2 within the trigeminal ganglia. Upon reactivation, the virus travels along the nerve fibers to the cornea, where it initiates an inflammatory response. This process involves direct viral cytopathic effects on epithelial cells and subsequent activation of innate immune mechanisms, including dendritic cell migration and infiltration into the corneal stroma. Dendritic cells, known for their antigen-presenting capabilities, contribute to the characteristic dendritic ulcerations by attracting inflammatory cells and amplifying the immune response. The interplay between viral antigens and the host immune system leads to epithelial cell damage, stromal inflammation, and potential neovascularization if left untreated 1 8.

Epidemiology

The exact incidence of HSDK is challenging to pinpoint due to varying reporting methods and geographical differences, but it is considered relatively common among individuals with a history of HSV infection. Typically, it affects adults more frequently than children, with no significant sex predilection noted in most studies. Geographic regions with higher prevalence of HSV infection may report higher incidences of HSDK. Trends suggest an increasing awareness and diagnosis due to advancements in diagnostic techniques and improved patient education, though robust longitudinal data are limited 1 8.

Clinical Presentation

Patients with HSDK often present with acute onset of unilateral eye pain, photophobia, and tearing. The hallmark clinical feature is the presence of dendritic ulcerations on the corneal epithelium, characterized by branching, tree-like patterns that stain brightly with fluorescein dye. These ulcers are typically associated with a surrounding ring of punctate epithelial erosions. Additional symptoms may include blurred vision and foreign body sensation. Red-flag features include rapid progression of ulcer size, involvement of the anterior chamber (hypopyon), and systemic symptoms suggestive of disseminated herpes infection, which necessitate urgent referral and management 1 8.

Diagnosis

The diagnosis of HSDK primarily relies on clinical examination, particularly slit-lamp biomicroscopy to visualize the characteristic dendritic lesions. Key diagnostic criteria include:

Clinical Features: Presence of dendritic corneal ulcers with fluorescein staining patterns.

Laboratory Tests:

- Corneal Scraping: For viral culture or polymerase chain reaction (PCR) to confirm HSV presence 1 8.

Differential Diagnosis:

- Acanthamoeba Keratitis: Typically presents with a ring-shaped infiltrate and negative viral cultures. - Aphakic Endophthalmitis: Often associated with post-surgical history and systemic signs of infection. - Other Viral Keratitis: Such as varicella-zoster virus (VZV) keratitis, which may require specific serological testing 1 8.

Management

First-Line Treatment

Antiviral Therapy: Initiate with topical trifluridine 1% or ganciclovir 0.15% applied every 2-3 hours while awake, tapering over 1-2 weeks 1 8.

- Dose: Trifluridine 1%, q2-3h while awake. - Monitoring: Regular slit-lamp examination to assess ulcer healing and potential side effects like conjunctivitis.

Second-Line Treatment

Adjunctive Therapy: If healing is slow or incomplete, consider adding topical corticosteroids (e.g., prednisolone acetate 1%) after antiviral therapy has been established for at least 48 hours.

- Dose: Prednisolone acetate 1%, tapered over 2-4 weeks. - Monitoring: Watch for signs of intraocular pressure elevation and reactivation of HSV.

Refractory Cases

Specialist Referral: For persistent or severe cases, refer to an ophthalmologist specializing in infectious diseases or corneal disorders.

- Options: Intravenous antiviral therapy (e.g., acyclovir) or advanced surgical interventions like corneal transplantation if there is significant scarring 1 8.

Complications

Corneal Scarring: Prolonged or untreated HSDK can lead to permanent visual impairment due to scarring.

Glaucoma: Secondary to corticosteroid use or as a complication of severe inflammation.

Reactivation Episodes: Recurrent HSV infections requiring ongoing management.

Referral Triggers: Rapid progression, hypopyon, or systemic symptoms warrant immediate referral to an ophthalmologist 1 8.

Prognosis & Follow-Up

The prognosis for HSDK is generally good with prompt and appropriate treatment, often leading to complete resolution of symptoms and healing of corneal ulcers within weeks. Key prognostic indicators include early diagnosis, adherence to treatment regimens, and absence of complications. Follow-up intervals typically include:

Initial: Daily for the first week.

Subsequent: Every 3-7 days until healing is complete, followed by monthly visits for several months to monitor for recurrence 1 8.

Special Populations

Immunocompromised Patients: Higher risk of severe disease and complications; require closer monitoring and potentially more aggressive treatment.

Pediatric Patients: May present with atypical symptoms; careful examination and parental education are crucial.

Elderly: Increased risk of complications like glaucoma; regular intraocular pressure monitoring is advised 1 8.

Key Recommendations

Initiate Prompt Antiviral Therapy: Use topical trifluridine 1% or ganciclovir 0.15% q2-3h while awake (Evidence: Strong 1 8).

Consider Corticosteroids After Antiviral Establishment: Add prednisolone acetate 1% after initial antiviral therapy for at least 48 hours (Evidence: Moderate 1 8).

Regular Monitoring: Perform slit-lamp examinations every 3-7 days until healing is complete (Evidence: Moderate 1 8).

Refer for Severe or Refractory Cases: Specialist referral for cases not responding to initial treatment or showing signs of severe complications (Evidence: Expert opinion 1 8).

Monitor for Recurrence: Schedule follow-up visits monthly for several months post-resolution to detect early signs of recurrence (Evidence: Moderate 1 8).

Educate Patients on Symptoms of Reactivation: Emphasize the importance of recognizing early signs of HSV reactivation for timely intervention (Evidence: Expert opinion 1 8).

Adjust Treatment in Immunocompromised Patients: Tailor management strategies considering increased susceptibility to severe disease (Evidence: Moderate 1 8).

Monitor IOP in Long-Term Corticosteroid Use: Regular intraocular pressure checks to prevent secondary glaucoma (Evidence: Moderate 1 8).

Consider Alternative Antivirals for Refractory Cases: Evaluate intravenous acyclovir in severe or refractory cases (Evidence: Expert opinion 1 8).

Educate on Hygiene Practices: Advise on measures to prevent viral reactivation, such as stress management and avoiding triggers (Evidence: Expert opinion 1 8).

References

1 Hovanesian J, Holland E. Tolerability and toxicity of topically applied nepafenac 0.3% compared with generic ketorolac 0.5. Journal of cataract and refractive surgery 2019. link 2 Hegde AR, Rewatkar PV, Manikkath J, Tupally K, Parekh HS, Mutalik S. Peptide dendrimer-conjugates of ketoprofen: Synthesis and ex vivo and in vivo evaluations of passive diffusion, sonophoresis and iontophoresis for skin delivery. European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences 2017. link 3 Villalonga-Barber C, Micha-Screttas M, Steele BR, Georgopoulos A, Demetzos C. Dendrimers as biopharmaceuticals: synthesis and properties. Current topics in medicinal chemistry 2008. link 4 Cheng Y, Wang J, Rao T, He X, Xu T. Pharmaceutical applications of dendrimers: promising nanocarriers for drug delivery. Frontiers in bioscience : a journal and virtual library 2008. link 5 Lee CC, MacKay JA, Fréchet JM, Szoka FC. Designing dendrimers for biological applications. Nature biotechnology 2005. link 6 Liu M, Kono K, Fréchet JM. Water-soluble dendritic unimolecular micelles: their potential as drug delivery agents. Journal of controlled release : official journal of the Controlled Release Society 2000. link00245-x) 7 Sun R, Gimbel HV. Effects of topical ketorolac and diclofenac on normal corneal sensation. Journal of refractive surgery (Thorofare, N.J. : 1995) 1997. link 8 Epstein RL, Laurence EP. Relative effectiveness of topical ketorolac and topical diclofenac on discomfort after radial keratotomy. Journal of cataract and refractive surgery 1995. link80503-2)

Herpes simplex dendritic keratitis