What are the recommended eye drops for treating bacterial and viral eye infections?

Eye Drops for Eye Infections

For bacterial conjunctivitis, use moxifloxacin 0.5% three times daily for 7 days or levofloxacin 1.5% as first-line therapy, as these FDA-approved fluoroquinolones provide broad-spectrum coverage with excellent efficacy. 1, 2, 3

Bacterial Conjunctivitis Treatment

First-Line Options (FDA-Approved)

Fluoroquinolone monotherapy is as effective as combination fortified antibiotics for most community-acquired bacterial conjunctivitis. 1

FDA-approved fluoroquinolones include:

• Moxifloxacin 0.5%: 1 drop three times daily for 7 days 3
• Levofloxacin 1.5%: Equivalent efficacy to older fluoroquinolones 1, 2
• Ciprofloxacin 0.3%: 1-2 drops every 2 hours while awake for 2 days, then every 4 hours for 5 days 4
• Ofloxacin 0.3%: 1-2 drops every 2-4 hours for 2 days, then 4 times daily for 5 days 5
• Besifloxacin 0.6%: Approved for bacterial conjunctivitis with good staphylococcal coverage 1, 2

Fourth-Generation Fluoroquinolones: Superior Gram-Positive Coverage

Moxifloxacin and gatifloxacin demonstrate better coverage of gram-positive pathogens than earlier-generation fluoroquinolones in head-to-head studies. 1, 2

• Moxifloxacin achieves 81% complete resolution by 48 hours versus 44% with polymyxin B/trimethoprim 6
• Microbiological eradication rates: 98.5% for H. influenzae, 86.4% for S. pneumoniae, 94.1% for S. aureus 7
• Fourth-generation agents are NOT FDA-approved for bacterial keratitis, though widely used off-label 1

Bacterial Keratitis (Corneal Ulcers)

Severity-Based Approach

For central or severe keratitis (infiltrate >2mm, deep stromal involvement, or hypopyon), initiate aggressive dosing with loading doses every 5-15 minutes, then hourly applications. 1

Mild-Moderate Keratitis

• Fluoroquinolone monotherapy: Ciprofloxacin 0.3%, ofloxacin 0.3%, or levofloxacin 1.5% 1
• Dosing for corneal ulcers: 2 drops every 15 minutes for 6 hours, then every 30 minutes for remainder of day 1, then hourly on day 2 4

Severe Keratitis or Treatment Failure

• Consider fortified antibiotic combination therapy (e.g., fortified cefazolin/tobramycin) 1
• Fortified antibiotics should be prepared by FDA-designated 503A/503B compounding pharmacies 1
• Add cycloplegic agents to decrease synechiae formation and pain 1

Resistance Considerations: Critical Pitfalls

Fluoroquinolone resistance is increasing, particularly with methicillin-resistant S. aureus (MRSA), which now comprises 42% of staphylococcal isolates. 1

• MRSA isolates are generally poorly responsive to fluoroquinolones but susceptible to vancomycin 1
• Risk factors for resistance: recent fluoroquinolone use, hospitalization, recent ocular surgery 1, 8
• Geographic variation exists: P. aeruginosa resistance to moxifloxacin increased from 19% to 52% in southern India (2007-2009) 1
• For MRSA keratitis, use fortified vancomycin 1

Special Pathogen Considerations

• Gonococcal conjunctivitis: Requires systemic ceftriaxone PLUS topical therapy 2, 8
• Chlamydial conjunctivitis: Requires systemic azithromycin or doxycycline 2, 8
• Multidrug-resistant Pseudomonas: Consider topical colistin 0.19% 1
• Vancomycin-resistant enterococcus: Topical linezolid may be used 1

Viral Conjunctivitis

No specific antiviral eye drops are recommended for routine viral conjunctivitis, which is typically self-limited. Supportive care with artificial tears and cool compresses is appropriate. For herpes simplex keratitis, topical antivirals (trifluridine, ganciclovir) are indicated, but this requires specialist evaluation.

Monitoring and Follow-Up

If no improvement occurs after 3-4 days of treatment, obtain conjunctival cultures and sensitivity testing. 8

• Re-evaluate for resistant organisms or non-bacterial causes 8
• Higher minimum inhibitory concentration correlates with slower re-epithelialization and worse visual outcomes 1
• Follow-up frequency should be based on severity: severe cases may require daily evaluation 2

Critical Caveats

• Never patch eyes or use therapeutic contact lenses in contact lens wearers with conjunctivitis due to increased risk of secondary bacterial keratitis 1, 8
• Do not taper antibiotics below 3-4 times daily as subtherapeutic dosing increases resistance risk 8
• Discontinue antibiotics once infection resolves to avoid corneal toxicity from prolonged use 8
• Ointments lack adequate corneal penetration for keratitis; reserve for adjunctive bedtime use in mild cases 1
• Subconjunctival injections may be helpful when adherence is questionable or fortified antibiotics are delayed 1