Introduction

Herpes Zoster Ophthalmicus (HZO) is the term for shingles that involves the ophthalmic branch of the trigeminal nerve (CNV1). It typically presents with unilateral involvement of the forehead, upper eyelid, eye or nose, corresponding to the CNV1 dermatome. Up to 50% of patients with HZO are at risk of ocular complications, including keratitis, uveitis, and even blindness. Early recognition and prompt treatment are essential to reduce the risk of sight-threatening complications.

Aetiology

• HZO results from reactivation of the Varicella Zoster Virus (VZV) within CNV1. This division of the trigeminal nerve innervates the forehead, upper eyelid, structures of the anterior eye, and parts of the nose.
• Primary infection with VZV typically presents as chickenpox, often occurring in childhood. Following resolution of the primary infection, VZV can remain latent in the dorsal root ganglia of the central nervous system for decades.
• Under certain conditions, such as immunosuppression, aging or stress, the virus may reactivate and travel to the sensory neurones of the skin, leading to shingles. When the CNV1 dermatome is involved, the condition is termed HZO.
• VZV is transmissible via direct contact with vesicular fluid or through inhalation of aerosol droplets. Individuals who have not previously been exposed to VZV are at risk of developing chickenpox.

Risk factors

• age over 50 years old
• Female
• Immunocompromised status
• Autoimmune conditions

Clinical Features

Prodromal Phase

• Neuropathic pain: Patients may experience burning or shooting pain along CNV1 dermatome up to 5 days prior to onset of rash
• Pruritus: Localized itching in the same area
• Unilateral headache

Rash

• Unilateral rash that strictly follows the V1 dermatome, typically affecting the forehead, upper eyelid and sometimes nose.
• Progression of the rash:
  • Begins as an erythematous maculopapular rash
  • Evolves into characteristic vesicles
  • Vesicles become pustular
  • Vesicles eventually ulcerate and crust over, typically within 10 days
  • Rash may take up to 4 weeks to completely resolve
  • Pain may last beyond resolution of rash (post-herpetic neuralgia).
• Hutchinson’s Sign
  • The presence of vesicular lesions on the tip of the nose is known as Hutchinson’s sign.
  • It reflects involvement of the nasociliary branch of CNV1.
  • Hutchinson’s sign is a strong predictor of ocular involvement as the nasociliary nerve also innervates structures within the eye. The presence of Hutchinson’s sign warrants urgent ophthalmic evaluation.

Ocular Features (may not always be present)

Differential diagnoses

A vesicular rash in the V1 dermatome is clinically indicative of HZO. However, Herpes Simplex Virus infection or impetigo should also be considered. Decreased corneal sensation is very suspicious of herpes simplex virus as opposed to HZO.

If swelling and erythema is present around the eye, preseptal cellulitis should be considered.

History taking

Key questions to ask during history taking for HZO:

• Previous Chickenpox infection or Varicella vaccination
• Prodromal symptoms
• Duration of symptoms
• Location of the rash, as well as progression or changes to the rash
• Systemic symptoms, including fever, chills, or malaise
• Risk factors for complications
  • Immunosuppression, e.g., chemotherapy, steroids, HIV, autoimmune conditions
• Pregnancy Status
  • Note: This is important due to potential risks of VZV to the fetus
  • Important to check if they are in close contact with anyone pregnant

Diagnosis and investigation

Clinical diagnosis: Diagnosis is primarily clinical, based on the characteristic unilateral vesicular rash in the CNV1 dermatomal distribution

Ophthalmic assessment: A thorough eye examination is essential, especially in the presence of hutchinson’s sign or when there are signs of ocular involvement:

• Visual acuity: assessed using a Snellen chart
• Intraocular pressure (IOP): measured using a tonometer
• Corneal assessment:
  • Slit lamp examination to assess for inflammation in any layers of the eye
  • Fluorescein stain to detect corneal epithelial defects

Laboratory confirmation: In atypical cases when there is diagnostic uncertainty, viral swabs of skin lesions can be taken for PCR. Cultures may also be sent for immunofluorescence assays to look for IgM specific to VZV

Infection control and prevention: Ensure you are wearing gloves during the physical examination to avoid direct contact with vesicles. Disinfect all surfaces and instruments touched during the examination

Management

• Analgesia: Use paracetamol or NSAIDs for pain. For neuropathic pain unresponsive to simple analgesics, agents such as amitriptyline and capsaicin cream can be considered.
• Antiviral therapy: Oral antivirals should be started within 72 hours of rash onset to reduce disease severity and complications.
  • Aciclovir 800mg orally five times a day for 7-10 days Famciclovir 500mg orally three times a dayValaciclovir 1000mg orally three times a day
  • If patient is unable to tolerate oral antivirals then intravenous acyclovir can be considered
• Ophthalmology referral: Urgent referral is required if Hutchinson’s sign, painful red eye, photophobia, or reduced visual acuity is present.
• Topical steroids: May be initiated by an ophthalmologist in combination with antivirals to manage ocular inflammation. To be used only under specialist supervision.
• Follow up: If skin rash is the only sign at presentation, then patient should be followed up to ensure they do not develop ocular manifestations.
• Patient education:
  • Avoid contact with pregnant, elderly, or immunocompromised individuals until all vesicles have crusted over.
  • Maintain good hygiene: wash hands frequently, avoid sharing towels, and keep the rash clean and dry.
• Prevention: Varicella-zoster vaccination is the emainstay of primary prevention, especially in older adults and high-risk populations, reducing the incidence and severity of HZ and its complications.

References

Lewis, K. et al. (2020) Herpes zoster ophthalmicus, American Academy of Ophthalmology. Available at: https://www.aao.org/eyenet/article/herpes-zoster-ophthalmicus-pearls.

National Institute for Health and Care Excellence (NICE) (2024) Shingles, NICE CKS. Available at: https://cks.nice.org.uk/topics/shingles/.

Oakley, A. (2015a) Herpes zoster, DermNet®. Available at: https://dermnetnz.org/topics/herpes-zoster.

Written by Dr Devika Nair & reviewed by Miss Sreekumari Pushpoth (consultant ophthalmologist)