A 32-year-old woman presents with a 5-day history of right eye pain, photophobia, and blurred vision. She reports a vesicular rash on the forehead and upper eyelid 2 days prior to eye symptoms. On examination, visual acuity is 6/9, and slit-lamp biomicroscopy reveals branching dendritic ulcers with terminal bulbs on the cornea. Corneal sensation is reduced. What is the most appropriate initial pharmacological management?

Question

Accepted Answer

C. Topical acyclovir 5 times daily plus oral acyclovir 400 mg 5 times daily for 10 days. ## Clinical Diagnosis

**Key Point:** The constellation of vesicular rash on V1 distribution (forehead/eyelid), dendritic ulcers with terminal bulbs, and reduced corneal sensation is pathognomonic for **Herpes Simplex Virus (HSV) keratitis**, specifically primary HSV-1 infection.

## Mechanism of Dendritic Ulcers

Dendritic ulcers in HSV keratitis result from viral replication in corneal epithelial cells. The characteristic **branching pattern with terminal bulbs** represents:
- Central area of infected epithelial cells (staining with rose bengal or lissamine green)
- Lateral extensions of viral spread along nerve endings
- Terminal bulbs at the tips of dendrites (areas of active viral replication)

## Management Algorithm

```mermaid
flowchart TD
  A[HSV Keratitis - Dendritic Ulcer]:::outcome --> B{Epithelial Disease Only?}:::decision
  B -->|Yes| C[Topical Acyclovir 5x/day]:::action
  B -->|No - Stromal/Endothelial| D[Add Oral Acyclovir + Topical Steroid]:::action
  C --> E[Plus Oral Acyclovir 400mg 5x/day × 10 days]:::action
  E --> F[Healing in 7-10 days]:::outcome
  D --> G[Prevent recurrent scarring]:::outcome
```

## Pharmacological Rationale

| Agent | Indication | Mechanism | Notes |
|-------|-----------|-----------|-------|
| **Topical Acyclovir 5%** | Epithelial HSV keratitis (dendritic/geographic) | Viral DNA polymerase inhibitor; high corneal penetration | First-line for epithelial disease |
| **Oral Acyclovir 400 mg 5×/day** | Systemic viral suppression | Achieves therapeutic aqueous humor levels | Reduces recurrence risk; essential in primary infection |
| Topical Ganciclovir | CMV keratitis (rare in immunocompetent) | Broader spectrum; requires phosphorylation by viral kinase | Not first-line for HSV; reserved for acyclovir resistance |
| Topical Cidofovir | Acyclovir-resistant HSV (immunocompromised) | Nucleotide analog; direct viral DNA inhibition | Expensive; reserved for resistant cases |
| Interferon-alpha | Adjunctive in severe stromal disease | Antiviral + immunomodulatory | Rarely used as monotherapy; outdated |

**High-Yield:** Combination of **topical acyclovir 5 times daily + oral acyclovir 400 mg 5 times daily** is the gold standard for primary HSV epithelial keratitis. Oral therapy reduces systemic viral load and prevents contralateral eye involvement and recurrences.

## Clinical Pearls

**Clinical Pearl:** Reduced corneal sensation in HSV keratitis is due to viral invasion of trigeminal nerve terminals and is a hallmark finding that distinguishes HSV from bacterial keratitis.

**Warning:** Do NOT use topical steroids in epithelial HSV keratitis — they promote geographic ulceration (coalescence of dendrites). Steroids are only indicated in stromal or endothelial disease, always with concurrent antiviral cover.

**Key Point:** The dendritic ulcer typically heals within 7–10 days with appropriate antiviral therapy. Failure to heal suggests acyclovir resistance (rare in immunocompetent hosts) or incorrect diagnosis.

## Expected Course

1. Epithelial healing: 7–10 days with topical + oral acyclovir
2. Corneal sensation recovery: weeks to months
3. Recurrence rate: ~50% within 5 years (oral prophylaxis reduces to ~20%)

![Viral Keratitis diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/3940.webp)

Answer

A. Topical interferon-alpha 6 times daily plus oral ribavirin

Answer

B. Topical cidofovir 1% 4 times daily for 3 weeks

Answer

D. Topical ganciclovir 5 times daily for 2 weeks

Explanation

Practice similar questions

Join our NEET PG community

Clinical Diagnosis

Mechanism of Dendritic Ulcers

Management Algorithm

Pharmacological Rationale

Clinical Pearls

Expected Course

Agent	Indication	Mechanism	Notes
Topical Acyclovir 5%	Epithelial HSV keratitis (dendritic/geographic)	Viral DNA polymerase inhibitor; high corneal penetration	First-line for epithelial disease
Oral Acyclovir 400 mg 5×/day	Systemic viral suppression	Achieves therapeutic aqueous humor levels	Reduces recurrence risk; essential in primary infection
Topical Ganciclovir	CMV keratitis (rare in immunocompetent)	Broader spectrum; requires phosphorylation by viral kinase	Not first-line for HSV; reserved for acyclovir resistance
Topical Cidofovir	Acyclovir-resistant HSV (immunocompromised)	Nucleotide analog; direct viral DNA inhibition	Expensive; reserved for resistant cases
Interferon-alpha	Adjunctive in severe stromal disease	Antiviral + immunomodulatory	Rarely used as monotherapy; outdated