What is the management of corneal infiltrate?

Management of Corneal Infiltrate

The management of corneal infiltrate depends critically on distinguishing infectious from sterile etiologies: obtain corneal scrapings for culture before initiating intensive broad-spectrum topical antibiotics, then consider adding topical corticosteroids only after 2-3 days of documented clinical improvement with antibiotics and pathogen identification (excluding fungal or Nocardia infections). 1

Initial Assessment and Diagnosis

The first priority is determining whether the infiltrate is infectious or sterile, as this fundamentally changes management:

Clinical features suggesting infectious keratitis:

• Mucopurulent discharge, significant pain, and photophobia 2
• Epithelial defect overlying the infiltrate (infectious infiltrates typically breach the epithelium, while sterile infiltrates usually have intact epithelium) 2, 3
• Larger infiltrate size, central corneal location, anterior chamber reaction, or hypopyon 2
• Focal infiltrate extending beyond the lamellar interface into deeper or superficial stroma 4

Obtain corneal scrapings immediately using a topical anesthetic and sterile instrument, collecting material from the base or periphery of the suspected infection. 1 A nylon-tipped flocked swab shows similar culture positivity to traditional methods. 1 If the flap interface is involved post-LASIK without surface ulceration, elevate the flap to access scrapings. 4

Treatment of Infectious Corneal Infiltrates

Initiate intensive broad-spectrum topical antibiotics immediately after obtaining cultures:

• Loading dose every 5-15 minutes, followed by hourly applications for central or severe keratitis 1
• Single fluoroquinolone therapy (ciprofloxacin 0.3%, ofloxacin 0.3%, or levofloxacin 1.5%) is as effective as combination fortified antibiotics 1, 5
• Consider fortified topical antibiotics for large, visually significant infiltrates, especially with hypopyon 1
• If interface involvement occurs, antibiotics can be applied directly to the flap interface after elevation 4

Follow patients daily initially until clinical improvement is confirmed. 1 If cultures are negative and clinical response is poor, stop antibiotics for 12-24 hours and reculture. 1

Adjunctive Corticosteroid Therapy

The American Academy of Ophthalmology's Bacterial Keratitis Preferred Practice Pattern provides specific guidance on corticosteroid use:

Corticosteroids may be added after at least 2-3 days of progressive improvement with topical antibiotics, typically after pathogen identification and ruling out fungal infection. 4, 1 The Sterile Corneal Ulcer Trial (SCUT) found no overall benefit of concurrent prednisolone phosphate 1% with antibiotics, but subgroup analysis showed potential benefit in Pseudomonas keratitis and severe bacterial keratitis. 4 Importantly, adding corticosteroids within 2-3 days (rather than after 4+ days) resulted in one-line better visual acuity at 3 months. 4

Critical contraindications and warnings:

• Never use corticosteroids for Nocardia keratitis - this results in poor visual outcomes 4
• Avoid corticosteroids until fungal infection is ruled out 4, 1
• Use the minimum amount required to control inflammation 4
• Monitor IOP closely, as corticosteroids can cause glaucoma and cataracts 4, 6
• Examine patients within 1-2 days after initiating corticosteroids 4

For patients already on corticosteroids at presentation, reduce or eliminate the regimen until infection is controlled. 4 Inflammation may temporarily increase due to lack of immune suppression, not necessarily worsening infection. 4

Special Infectious Considerations

Severe infections may require flap amputation to control infection. 4 Unusual organisms including atypical mycobacteria, methicillin-resistant S. aureus, nocardia, fungi, and HSV have been reported post-LASIK. 4

Chronic topical immunotherapy increases risk of infectious crystalline keratopathy, requiring discontinuation of immunotherapy and long-term antimicrobial therapy, often with surgical intervention. 4

Treatment of Sterile Corneal Infiltrates

Topical corticosteroids are the mainstay of treatment for sterile infiltrates, but concurrent topical antibiotics are strongly recommended as prophylaxis. 2 This approach acknowledges the diagnostic difficulty even experienced cornea specialists face in distinguishing sterile from infectious infiltrates. 2

For contact lens-related sterile infiltrates:

• Discontinue contact lens wear 2
• Consider topical fluorometholone alone in highly selected cases with strict follow-up (3-4 day reassessment) 7
• However, the safer approach is concurrent antibiotics with corticosteroids 2

Close follow-up is crucial for patients on corticosteroids, as immunocompromised patients are prone to fungal infections. 2

Post-Viral Subepithelial Infiltrates

For adenoviral subepithelial infiltrates occurring 1+ weeks after conjunctivitis onset:

• Mild cases: observation is sufficient 4
• Cases with blurring, photophobia, and decreased vision: topical corticosteroids at minimum effective dose 4
• Slowly taper to minimum effective dose 4
• Consider fluorometholone or loteprednol (less likely to cause IOP elevation or cataracts) 4
• Cyclosporine drops (0.05% to 1%) are helpful alternatives for reducing infiltrates 4
• Monitor regularly with IOP measurement and slit-lamp examination 4

Note: Subepithelial infiltrates can recur in patients undergoing PRK or LASIK after adenoviral infection. 4

Critical Pitfalls to Avoid

• Never delay corneal scraping and culture - this leads to ineffective treatment 1
• Avoid tetracaine for corneal scraping - it has antimicrobial effects that interfere with cultures 1
• Do not use corticosteroids for Nocardia or fungal keratitis - outcomes are poor 4, 1
• Every corneal ring infiltrate with compromised epithelium should be scraped and treated as infectious until proven otherwise 3
• Do not patch contact lens-related corneal abrasions - this increases risk of secondary bacterial keratitis 1, 5
• Recognize that even microbiological ulcers may develop immunological rings requiring anti-inflammatory treatment after infection control 3