What is the appropriate treatment for a patient presenting with a corneal ulcer?

Treatment of Corneal Ulcer

Initiate immediate intensive broad-spectrum topical antibiotic therapy after obtaining corneal scrapings for culture, using either fluoroquinolone monotherapy (moxifloxacin 0.5% or gatifloxacin 0.5%) or fortified antibiotic combinations, with loading doses every 5-15 minutes followed by hourly around-the-clock application for severe or central ulcers. 1, 2

Immediate Diagnostic Steps

• Obtain corneal scrapings from the ulcer base and periphery using a sterile blade under slit-lamp visualization after applying proparacaine 0.5% anesthetic 2
• Scraping is mandatory when hypopyon is present or when there are ≥1+ cells in the anterior chamber 2
• Use a nylon-tipped flocked swab as an alternative collection method with similar culture positivity rates 1
• Inoculate samples directly onto appropriate culture media or place in transport media and promptly deliver to the laboratory 1

Initial Antibiotic Regimen Selection

For severe or central keratitis (deep stromal involvement, infiltrate >2mm, or hypopyon present):

• Use fortified topical antibiotics for large and/or visually significant corneal infiltrates, especially with hypopyon 3, 1
• Fortified antibiotics are preferred for patients with recent fluoroquinolone use, hospitalization, advanced age, recent ocular surgery, or known resistant organisms due to increasing fluoroquinolone resistance (42% methicillin resistance in Staphylococcal isolates) 3, 2

For small noncentral ulcers:

• Fluoroquinolone monotherapy with moxifloxacin 0.5% or gatifloxacin 0.5% is as effective as fortified combinations for most bacterial keratitis 2
• FDA-approved options include ciprofloxacin 0.3%, ofloxacin 0.3%, and levofloxacin 1.5% 3, 1

Dosing Protocol

• Apply loading doses every 5-15 minutes initially 1, 2
• Continue hourly applications around-the-clock for severe cases 1, 2
• Apply antibiotic ointment at bedtime during the intensive phase 2
• Topical antibiotics achieve high tissue levels and are the preferred treatment method over systemic therapy in most cases 3, 1

Essential Adjunctive Measures

• Apply atropine 1% or homatropine 5% cycloplegic agents to reduce pain and prevent synechiae formation from anterior segment inflammation 3, 2
• Provide aggressive lubrication with preservative-free artificial tears 2
• Prophylactic broad-spectrum topical antibiotics (e.g., moxifloxacin drops four times daily) are indicated in the presence of corneal fluorescein staining or frank ulceration 3

Monitoring and Treatment Modification

• Examine daily until clear improvement is documented 1, 2
• Signs of positive response include: reduced pain and discharge, decreased eyelid edema and conjunctival injection, consolidation and sharper demarcation of infiltrate borders, reduced stromal infiltrate density without progressive thinning, and initial re-epithelialization 2
• If cultures are negative and clinical response is poor after 48-72 hours, consider stopping antibiotic treatment for 12-24 hours and then reculturing 1
• Modify therapy based on culture results and sensitivities if no improvement at 48-72 hours 2

Corticosteroid Therapy Timing

Add topical corticosteroids only after meeting ALL three criteria:

1. At least 2-3 days of progressive improvement with antibiotics 1, 2
2. After pathogen identification 1, 2
3. After ruling out fungal infection 1, 2

• The American Academy of Ophthalmology found no overall benefit of routine corticosteroid use, but potential benefit exists in Pseudomonas keratitis and severe cases 2
• Application of topical corticosteroid drops (e.g., nonpreserved dexamethasone 0.1% twice daily) may reduce ocular surface damage 3
• Use the minimum amount required to control inflammation 1
• Corticosteroids are contraindicated in Nocardia keratitis 1
• Patients with pre-existing corticosteroid therapy should have their regimen reduced or eliminated until the infection is controlled 1

Surgical Intervention Indications

Consider surgery when:

• Progressive stromal thinning occurs despite maximal medical therapy 2
• Impending or frank corneal perforation develops 2
• No response to medical treatment after 7-10 days 2

Surgical options include:

• Tissue adhesive (cyanoacrylate) with bandage contact lens for small perforations or marked thinning 3, 2
• The area must be dry and de-epithelialized for adhesive to adhere properly 3
• Use the least amount of glue that will seal or support the defect 3
• Amniotic membrane transplantation 2
• Therapeutic penetrating keratoplasty 2
• Conjunctival flaps 2

Critical Pitfalls to Avoid

• Never delay obtaining cultures before starting antibiotics - this leads to ineffective treatment 1
• Avoid using tetracaine as an anesthetic for corneal scraping - it has antimicrobial effects that interfere with culture results 1
• Do not patch the eye or use therapeutic contact lenses in contact lens wearers with corneal abrasions - this increases risk of secondary bacterial keratitis 3, 1
• Never use corticosteroids in Nocardia or fungal keratitis - this leads to poor outcomes 1
• Avoid chronic prophylactic antibiotic use - this may promote growth of resistant organisms 3, 1
• Do not use fibrin glue for corneal perforations or descemetoceles - it biodegrades rapidly before healing can occur 3
• Gatifloxacin ophthalmic solution may cause corneal endothelial cell injury if introduced directly into the anterior chamber 4

Prevention and Patient Education

• Educate patients with risk factors about increased risk and signs/symptoms warranting prompt ophthalmological consultation 1
• Treat underlying ocular surface diseases such as epithelial defects, tear deficiency, entropion, or lagophthalmos 1
• Prescribe prophylactic antibiotics for contact lens wearers with corneal abrasions and for patients with trauma-related abrasions, starting within 24 hours to prevent ulceration 3, 1
• Educate about risk of permanent visual loss and need for strict adherence to treatment 2
• For contact lens wearers, discuss risks of overnight wear and consider switching to daily disposable lenses 2