Polymyxin B Dosing for Metal-Related Corneal Abrasion
For an adult with a metal-related corneal abrasion, administer polymyxin B 0.1% ophthalmic solution one drop to the affected eye every 3 hours (maximum 6 doses per day) for 7-10 days. 1
Standard Dosing Regimen
- The FDA-approved dosing for polymyxin B ophthalmic solution in mild to moderate infections is one drop every three hours, with a maximum of 6 doses per day, continued for 7 to 10 days 1
- Treatment should be initiated within 24 hours of the abrasion to maximize effectiveness in preventing bacterial ulceration and infection 2, 3
Critical Context for Metal-Related Abrasions
- Metal-related corneal abrasions require broad-spectrum topical antibiotic coverage to prevent both bacterial and fungal infection following trauma 2, 3
- Prophylactic topical antibiotics have been shown to prevent ulceration specifically when started within 24 hours of the abrasion 2, 3
Important Clinical Caveats
- Never patch the eye in any patient with corneal abrasion, as patching does not improve pain, may delay healing, and increases infection risk 3
- If the patient wears contact lenses, antipseudomonal coverage with fluoroquinolones (such as moxifloxacin or levofloxacin) is strongly preferred over polymyxin B due to the dramatically increased risk of Pseudomonas keratitis 3
- Polymyxin B ointment formulations lack adequate corneal penetration for optimal therapeutic benefit and should be reserved for bedtime use in less severe cases only 2
When to Escalate Treatment
- Immediately escalate to hourly fluoroquinolone drops if any of the following develop: central infiltrate >2mm, deep stromal involvement, presence of hypopyon, or signs of bacterial keratitis (increasing pain, purulent discharge, corneal infiltrate) 2, 3
- Obtain cultures before initiating treatment if a central infiltrate >2mm is present 3