What is the best treatment approach for a patient with a corneal abrasion who does not wear contact lenses, given the availability of topical Polytrim (polymyxin B trimethoprim) and Erythromycin?

Treatment of Corneal Abrasion in Non-Contact Lens Wearer

For a non-contact lens wearing patient with corneal abrasion, use either Polytrim (polymyxin B-trimethoprim) or erythromycin ointment as prophylactic antibiotic therapy, with Polytrim drops preferred during the day and erythromycin ointment reserved for bedtime use. 1

Antibiotic Selection and Rationale

Primary Treatment Approach

• Topical antibiotic drops are the preferred method because they achieve higher corneal tissue levels compared to ointments 1, 2
• Polytrim (polymyxin B-trimethoprim) solution provides broad-spectrum coverage against both gram-positive and gram-negative organisms, making it appropriate for prophylaxis in traumatic corneal abrasions 3
• The combination contains polymyxin B sulfate 10,000 units/mL and trimethoprim 1 mg/mL, providing coverage against common bacterial pathogens 3

Dosing Regimen

• Apply Polytrim drops 4 times daily for prophylaxis 4
• Add erythromycin ointment at bedtime for additional protection and lubrication during sleep 1, 2
• Treatment should be initiated within 24 hours of the abrasion for maximum effectiveness in preventing ulceration 1

Why Ointment Alone Is Suboptimal

• Ocular ointments lack sufficient solubility and cannot penetrate the cornea adequately for optimal therapeutic benefit 1, 2
• Ointments may be useful at bedtime in less severe cases and as adjunctive therapy to drops, but should not be used as monotherapy 2
• Erythromycin ointment alone would provide inferior corneal penetration compared to solution formulations 1

Critical Management Points

What This Patient Does NOT Need

• No eye patching - patching does not improve pain and may delay healing 4, 5
• No antipseudomonal coverage required - this is specifically indicated only for contact lens-related abrasions 1
• Since this patient does not wear contacts, standard broad-spectrum prophylaxis is sufficient 1

Pain Management

• Prescribe oral acetaminophen or NSAIDs for pain control 2, 4
• Topical NSAIDs (if available) can significantly reduce pain, photophobia, and foreign body sensation within 24 hours 6
• Cycloplegics are not routinely needed for uncomplicated abrasions unless substantial anterior chamber inflammation is present 2

Follow-Up and Warning Signs

When Follow-Up Is Required

• Small abrasions (≤4mm) with resolving symptoms and normal vision may not require follow-up 5
• All other patients should be re-evaluated in 24 hours to assess healing and rule out infection 5

Red Flags Requiring Immediate Referral

• Increasing pain, purulent discharge, or corneal infiltrate suggesting infection 2, 4
• Vision loss or irregular pupil 2
• Symptoms that worsen or fail to improve within 24-48 hours 5

Important Caveats

Antibiotic Resistance Concerns

• While evidence for antibiotic prophylaxis preventing infection is limited, guidelines support its use to prevent bacterial keratitis when started within 24 hours 1, 7
• Avoid chronic or prolonged antibiotic use as this may promote resistant organisms 1
• A 5-7 day course is typically sufficient for prophylaxis 8

Evidence Limitations

• A Cochrane review found very low certainty evidence regarding antibiotic prophylaxis effectiveness, but clinical guidelines still recommend it based on the low risk of treatment and potential severity of untreated infection 7
• The recommendation prioritizes patient safety and prevention of sight-threatening complications over the limited evidence base 1