A 48-year-old man with a history of recurrent herpes labialis presents with right eye pain, photophobia, and blurred vision for 3 days. On slit-lamp examination, the cornea shows a geographic ulcer with rolled edges and granular base after fluorescein staining. Corneal sensation is markedly reduced. He reports having used topical dexamethasone 0.1% drops for the past 10 days for presumed bacterial keratitis. What is the most likely diagnosis and the immediate management?

Explanation

## Diagnosis: Geographic HSV Keratitis (Steroid-Induced) **Key Point:** Geographic ulceration of the cornea in a patient with prior HSV and recent steroid use is pathognomonic for steroid-induced geographic ulcer — a serious complication of topical corticosteroid use in HSV keratitis. **High-Yield:** Geographic ulcers represent coalescence and expansion of dendritic ulcers, typically triggered by: - Inappropriate topical corticosteroid use in active HSV keratitis - Immunosuppression - Delayed diagnosis or inadequate antiviral therapy ### Pathophysiology of Steroid-Induced Geographic Ulcer ```mermaid flowchart TD A[HSV epithelial keratitis<br/>Dendritic ulcer]:::outcome --> B[Topical corticosteroid applied]:::urgent B --> C[Viral replication suppressed<br/>Immune response dampened]:::action C --> D[Ulcer edges expand<br/>Dendritic borders coalesce]:::action D --> E[Geographic ulcer<br/>Rolled edges, granular base]:::outcome E --> F{Continued steroids?}:::decision F -->|Yes| G[Corneal perforation<br/>Scarring, vision loss]:::urgent F -->|No| H[Intensive antivirals<br/>Ulcer healing]:::action ``` ### Clinical Features of Geographic Ulcer | Feature | Dendritic Ulcer | Geographic Ulcer | |---------|-----------------|------------------| | **Morphology** | Branching, tree-like | Irregular, map-like | | **Edges** | Sharp, terminal bulbs | Rolled, scalloped | | **Base** | Clear | Granular, necrotic | | **Size** | Small (2–3 mm) | Large (>5 mm) | | **Cause** | Primary HSV infection | Steroid use, immunosuppression | | **Prognosis** | Good with antivirals | Guarded; risk of perforation | **Clinical Pearl:** The rolled edges and granular base of a geographic ulcer reflect active viral replication at the ulcer margin with necrotic debris in the center — steroids paradoxically worsen this by suppressing local immunity. ### Immediate Management of Geographic HSV Keratitis 1. **Discontinue all topical corticosteroids immediately** — this is the single most critical step. 2. **Intensive topical antiviral therapy**: - Acyclovir 5% ointment: every 1–2 hours while awake (not less frequent than dendritic keratitis) - Alternative: Ganciclovir 0.15% gel every 2–3 hours 3. **Systemic antivirals** (adjunctive): - Acyclovir 800 mg orally 4–5 times daily × 10–14 days - Valacyclovir 500–1000 mg three times daily 4. **Cycloplegic agents** (tropicamide) for pain and anterior uveitis management. 5. **Avoid all topical steroids** until complete epithelialization and then only under antiviral cover for immune stromal keratitis. 6. **Monitor closely** (daily or every 2 days initially) for signs of perforation (Seidel test, anterior chamber reaction). **Warning:** Topical steroids in HSV keratitis are a classic NEET PG trap. Even low-potency steroids can trigger geographic ulceration. Steroids are contraindicated in epithelial keratitis but may be cautiously used in immune stromal keratitis only after epithelialization and with concurrent antiviral therapy. **Mnemonic: GEOGRAPHIC** — **G**ranular base, **E**xpanded dendritic, **O**phthalmic HSV, **G**raphic map-like, **R**olled edges, **A**void steroids, **P**erforation risk, **H**igh-dose antivirals, **I**ntensive therapy, **C**ontinue antivirals, **U**rge discontinuation of steroids. [cite:Khurana 6e Ch 5; Parson 5e Ch 7]