Management of Grade +4 Anterior Chamber Reaction 12 Years Post-LASIK with Negative Fluorescein Stain
This presentation strongly suggests infectious keratitis requiring immediate corneal scraping for cultures and empiric broad-spectrum topical antibiotics, even with a negative fluorescein stain. 1
Why This is Infectious Keratitis, Not DLK
A grade +4 anterior chamber reaction occurring 12 years after LASIK is highly suspicious for microbial keratitis rather than typical postoperative inflammation. 1 The key distinguishing features are:
- Diffuse lamellar keratitis (DLK) characteristically presents with little or no anterior chamber inflammation and typically occurs within the first few days after surgery, not years later. 2
- Microbial keratitis after LASIK presents with marked anterior chamber reaction, along with pain, redness, and photophobia. 2, 1
- The negative fluorescein stain does not exclude infection—focal corneal infiltrates in LASIK-associated infections often extend beyond the lamellar interface into deeper or more superficial stroma and may not always show epithelial defects. 2
Immediate Diagnostic Steps
Obtain corneal scrapings immediately from any visible infiltrate and send for bacterial, fungal, and viral cultures, including atypical mycobacteria and Nocardia species. 1 The microbiologic spectrum of LASIK-related infections differs from other corneal infections and includes atypical mycobacteria, methicillin-resistant Staphylococcus aureus, Nocardia, fungi, and herpes simplex virus. 2, 1
If the flap interface is involved but no surface ulceration is visible, elevate the LASIK flap to allow direct access for scrapings. 2, 1 This is critical because interface infections may not manifest with obvious epithelial defects.
Empiric Treatment Protocol
Initiate intensive broad-spectrum topical antibiotics immediately after obtaining cultures. 2, 1 Based on culture sensitivity data for the most common organisms (Pseudomonas aeruginosa and Staphylococcus aureus), fortified vancomycin and tobramycin are recommended as first-line therapy. 3
If flap elevation is performed for scrapings, apply antibiotics directly onto the interface. 2, 1 This ensures adequate drug penetration to the site of infection.
Adjust the antimicrobial regimen according to culture results and clinical response. 1 Clinical improvement should be evident within 48–72 hours; absence of response mandates review of culture data and modification of treatment. 1
Critical Pitfalls to Avoid
Do not use topical corticosteroids empirically. 1 Lack of response to corticosteroids should raise suspicion for microbial keratitis, and steroids can worsen infection and mask its progression. 1 Prior use of intensive topical steroids may modify the clinical presentation and increase infection severity. 2, 1 The FDA label for prednisolone acetate specifically warns that if inflammation or pain persists longer than 48 hours or becomes aggravated, the patient should discontinue use and consult a physician. 4
Measure intraocular pressure peripherally to the flap edge, not centrally, to assess for pressure-induced stromal keratitis, as interface fluid can give falsely low central readings. 1
Surgical Intervention Criteria
Severe infection involving the flap or deep stromal layers may necessitate flap amputation to achieve infection control. 2, 1 When medical therapy fails to halt disease progression within 48–72 hours, surgical debridement should be considered. 1
Epithelial ingrowth is a recognized risk factor for the development of microbial keratitis after LASIK and may be present in this case. 2, 1
Expected Clinical Course
Infectious keratitis after LASIK follows a progressive course with worsening pain, redness, and photophobia, requiring aggressive antimicrobial treatment. 1 The timing and severity vary greatly depending on the causative organism, especially if intensive topical corticosteroids have been used previously. 2