A 38-year-old woman from Mumbai presents with a 3-week history of left-sided facial swelling, pain, and vesicular rash in the distribution of the ophthalmic (V1) and maxillary (V2) divisions of the trigeminal nerve. She also reports ipsilateral eye pain and blurred vision. Examination reveals conjunctivitis and corneal involvement. What is the most appropriate immediate next step?

Explanation

## Clinical Diagnosis: Herpes Zoster Ophthalmicus (HZO) **Key Point:** This is herpes zoster involving the ophthalmic and maxillary divisions of CN V (V1 and V2), with corneal involvement — a medical emergency. **High-Yield:** Herpes zoster ophthalmicus (HZO) is characterized by: - Vesicular rash in V1 ± V2 distribution - Ocular involvement: conjunctivitis, keratitis, anterior uveitis - Risk of post-herpetic neuralgia (PHN), vision loss, and chronic pain - **Hutchinson's sign** (vesicles on nose tip) = high risk of corneal involvement ## Management Algorithm for Herpes Zoster Ophthalmicus ```mermaid flowchart TD A[HZO suspected: rash in V1/V2 + ocular symptoms]:::outcome --> B[Urgent ophthalmology referral]:::action B --> C[Systemic antiviral: Acyclovir 800 mg 5x daily]:::action C --> D{Corneal involvement?}:::decision D -->|Yes: keratitis, epithelial defect| E[Topical antiviral + lubricants + cycloplegic]:::action D -->|No: conjunctivitis only| F[Topical lubricants + cycloplegic]:::action E --> G[Ophthalmology follow-up in 24-48 hrs]:::action F --> G G --> H{Complications: uveitis, scleritis?}:::decision H -->|Yes| I[Add topical corticosteroids + NSAIDs]:::action H -->|No| J[Continue antivirals + supportive care]:::action ``` **Clinical Pearl:** The presence of **corneal involvement** (keratitis, epithelial defect) requires BOTH systemic AND topical antivirals. Topical acyclovir ointment is essential to prevent corneal scarring and vision loss. ## Why Urgent Ophthalmology Referral + Systemic Acyclovir? | Step | Rationale | |------|----------| | **Urgent referral** | Ophthalmologist must assess corneal status, anterior chamber, intraocular pressure; risk of vision-threatening complications | | **Systemic acyclovir** | Reduces viral load, duration of rash, and risk of PHN; must start within 72 hours of rash onset | | **Dosing: 800 mg 5x daily** | Standard for HZO; higher doses (IV) reserved for immunocompromised or severe disseminated disease | | **Topical antiviral** | Acyclovir ointment applied to eye reduces corneal viral replication and prevents scarring | | **Cycloplegic agent** | Relieves pain from ciliary spasm and anterior uveitis | **Mnemonic:** **HZO-URGENT** = **H**erpes **Z**oster **O**phthalmicus requires **U**rgent referral + **R**efer to ophthalmology + **G**ive systemic antiviral + **E**ye topical antiviral + **N**ot just topical alone + **T**reat within 72 hours **Warning:** Do NOT rely on topical acyclovir alone — systemic therapy is mandatory to reduce PHN risk and systemic viral dissemination.