Makindo Medical Notes

Related Subjects: |Herpes Varicella-Zoster (Shingles) Infection |Chickenpox Varicella Infection |Varicella Cerebral Vasculopathy |Herpes Viruses |Herpes Zoster Ophthalmicus (HZO) Shingles

The virus can affect the uveal tract and, in immunosuppressed patients, the retina, potentially leading to acute retinal necrosis. A vaccine is now available to prevent severe infection in older patients. Refer to ophthalmology for any patient with red eye, visual symptoms, or Hutchinson's sign, as they require immediate ophthalmology review.

About

• Herpes Zoster Ophthalmicus (HZO): A reactivation of the varicella-zoster virus (VZV) in the ophthalmic branch of the trigeminal nerve (cranial nerve V).
• Shingles: Reactivation of the dormant VZV, typically presenting as a painful vesicular rash following a dermatomal distribution.

Aetiology

• Primary infection: Varicella (chickenpox) usually occurs in childhood.
• Dormancy: After primary infection, VZV remains latent in the dorsal root ganglia or cranial nerve sensory ganglia.
• Reactivation: Triggered by factors such as stress, immunosuppression, sunlight, or trauma, leading to shingles.
• Ocular involvement: Occurs when the virus reactivates in the ophthalmic branch of the trigeminal nerve, resulting in HZO.

Predisposing Factors

• Age: Most common in individuals aged 60+ but can occur at any age.
• Immunocompromised states: Including HIV/AIDS, organ transplants, cancer, or those on immunosuppressive medications (e.g., chemotherapy, steroids).
• Physical or emotional stress: Can also contribute to reactivation.

Images

Clinical Features

• Prodromal symptoms: Malaise, headache, fever, and tenderness of the skin before rash appearance.
• Dermatomal rash: Unilateral, painful vesicular rash following the ophthalmic branch of the trigeminal nerve, usually affecting the forehead, scalp, and upper eyelid. Crusting occurs within 1-2 weeks.
• Hutchinson's sign: Rash at the tip, side, or root of the nose indicates a higher risk of ocular involvement (due to nasociliary nerve involvement).
• Pain: May precede the rash by days and can be severe. Post-herpetic neuralgia may persist after the rash resolves.
• Eye involvement: May include conjunctivitis, keratitis, uveitis, and possible permanent vision loss if untreated.
• Neurological complications: Cranial nerve palsies, optic neuritis, encephalitis, and myelitis.

Ocular Complications

• Conjunctivitis: Mucopurulent discharge; typically resolves in a week.
• Keratitis: Inflammation of the cornea, leading to reduced corneal sensation (neurotrophic keratitis).
• Scleritis/Episcleritis: Inflammation of the sclera; episcleritis is more common but less severe.
• Uveitis: Anterior uveitis, associated with photophobia and visual disturbances.
• Secondary glaucoma: Increased intraocular pressure from inflammation or corticosteroid use.
• Retinitis/Choroiditis: In immunocompromised individuals, the virus can cause inflammation of the retina and choroid, leading to vision loss.
• Optic neuritis: Inflammation of the optic nerve, causing pain with eye movement and vision loss.

Post-Herpetic Neuralgia (PHN)

• Occurs in about 10-15% of patients, especially in older individuals.
• Characterized by persistent pain at the site of the rash even after it heals, lasting weeks to months.
• Can be debilitating and resistant to standard pain relief.

Differential Diagnosis

• Herpes Simplex Virus (HSV) keratitis: Similar eye involvement but without the typical dermatomal rash of zoster.
• Cellulitis: Particularly preseptal or orbital cellulitis, which can cause a painful, swollen eye.
• Contact dermatitis, atopic eczema, or impetigo: May cause similar rashes but lack the viral prodrome and neuralgia.

Management

• Antiviral therapy: Early treatment with oral aciclovir (within 72 hours of rash onset) can reduce the risk of eye complications and post-herpetic neuralgia. Dosage: Aciclovir 800 mg orally five times per day for 7-10 days. Alternatives include valaciclovir or famciclovir.
• Topical steroids: For severe eye inflammation (e.g., uveitis or scleritis), topical corticosteroids (e.g., prednisolone acetate 1% drops) are used in conjunction with antiviral therapy under ophthalmologist supervision.
• Pain management: Nonsteroidal anti-inflammatory drugs (NSAIDs), opioids for severe pain, or anticonvulsants (e.g., gabapentin, pregabalin) for post-herpetic neuralgia.
• Antibiotics: If secondary bacterial infection occurs, consider topical or systemic antibiotics.
• Ophthalmology referral: Any patient with ocular involvement or suspected HZO should be referred to an ophthalmologist urgently.
• Immunosuppressed patients: Consider intravenous aciclovir if severe infection or if oral treatment is insufficient.
• Prevention: Vaccination (e.g., Shingrix) is recommended for older adults to prevent shingles and its complications. It is particularly indicated for those aged 70-79 years. See BNF reference.

Prevention

• Shingles vaccine: Reduces the risk of shingles and post-herpetic neuralgia. Two vaccines are available in the UK: Zostavax (live vaccine) and Shingrix (non-live, adjuvanted vaccine). Shingrix is now the preferred vaccine, especially in immunocompromised patients.
• Isolation: Avoid contact with pregnant women, immunocompromised individuals, and those without immunity to varicella (e.g., non-vaccinated children) until the rash has completely crusted over.

References

• Ophthalmic herpes zoster
• Shingles NICE guidance November 2019