What is the recommended ophthalmic treatment for keratitis?

Treatment of Keratitis

For bacterial keratitis, initiate topical fluoroquinolone monotherapy (moxifloxacin, gatifloxacin, or levofloxacin) for small, non-central ulcers, or fortified combination therapy (vancomycin + ceftazidime or cefazolin + tobramycin) for large, central, or severe ulcers with intensive dosing every hour after a loading dose. 1

Initial Treatment Strategy

The treatment approach depends on ulcer severity and location:

Mild to Moderate Cases (Small, Non-Central Ulcers)

• Topical fluoroquinolone monotherapy is the preferred first-line treatment 1
• Most community-acquired cases resolve with empiric topical therapy alone 1
• FDA-approved options include:
  • Ciprofloxacin 0.3%
  • Ofloxacin 0.3%
  • Levofloxacin 1.5% 1
• Fourth-generation fluoroquinolones (moxifloxacin, gatifloxacin) show superior efficacy, particularly for gram-positive coverage, though not FDA-approved for keratitis 1

Recent network meta-analysis evidence (2025) demonstrates that moxifloxacin heals ulcers approximately 7 days faster than ciprofloxacin (MD -6.81 days), while ofloxacin shows similar healing times to ciprofloxacin 2. This makes moxifloxacin a superior choice when available.

Severe Cases (Central, Large >2mm, or Deep Stromal Involvement)

• Fortified combination therapy is recommended 1
• Vancomycin + ceftazidime ranks highest for efficacy (heals 6 days faster than ciprofloxacin) and has the lowest risk of adverse effects 2
• Alternative: Cefazolin + tobramycin (heals 5.6 days faster than ciprofloxacin) 2
• These combinations are particularly important when hypopyon is present 1

Dosing Regimen

Severe/Central Keratitis

• Loading dose: Every 5-15 minutes initially
• Maintenance: Every hour around the clock 1
• Critical dosing consideration: For ciprofloxacin specifically, minimum 47 drops on Day 1 are required to prevent treatment failure 3
• For ofloxacin, minimum 24 drops on Day 1 3

Mild Cases

• Less frequent dosing acceptable
• Ointments may be used at bedtime as adjunctive therapy (though they penetrate poorly) 1

Adjunctive Measures

Cycloplegic agents should be added to:

• Decrease synechiae formation
• Reduce pain from anterior chamber inflammation 1

Corticosteroid Use

Corticosteroids may be considered ONLY after 48 hours of antibiotic therapy when:

• The causative organism is identified, AND/OR
• The infection has responded to therapy 1

Absolute contraindications for steroids:

• Suspected Acanthamoeba
• Nocardia
• Fungal keratitis 1

Important Caveats

Antibiotic Resistance Concerns

• MRSA and Pseudomonas show increasing fluoroquinolone resistance (2005-2015 period) 1
• Methicillin resistance found in 42% of Staphylococcal isolates 1
• Higher minimum inhibitory concentration correlates with worse outcomes (slower healing, more vision loss) 1

Expected Clinical Course

• Pseudomonas and gram-negative keratitis may show increased inflammation in first 24-48 hours despite appropriate therapy - this is expected and does not indicate treatment failure 1

Alternative Delivery Methods (Use Sparingly)

• Subconjunctival injections: Consider when adherence is questionable or fortified antibiotics are delayed 1
• Systemic therapy: Reserved for scleral/intraocular extension or systemic infection (e.g., N. gonorrhoeae) 1
• Collagen shields/contact lenses soaked in antibiotics: Potential for drug toxicity and hypoxia; can be displaced 1

When to Obtain Cultures

While most small non-central ulcers resolve empirically, smears and cultures are specifically indicated in:

• Large or central ulcers
• Severe cases with deep stromal involvement
• Cases not responding to initial therapy
• Contact lens-related cases (highest risk factor in the US) 1

Prevention in High-Risk Situations

Topical antibiotics should be prescribed prophylactically for:

• Contact lens wearers with corneal abrasion
• Any corneal abrasion following trauma 1

Critical: Do NOT patch the eye in contact lens-associated abrasions - this increases bacterial keratitis risk 1