Etiology, pathophysiology, diagnostic delay, characteristics and treatment of post-LASIK infection of keratitis due to nontuberculous mycobacteria (NTM)

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.Nontuberculous Mycobacterium (NTM) is a rare but critical pathogen in post-surgical infectious keratitis, especially after refractive surgeries like LASIK. Due to its slow growth and deep stromal localization, early detection is difficult and misdiagnosis as non-infectious DLK or viral keratitis is common.

🔹 Microbial Profile & Pathogenesis

• NTM refers to all mycobacteria excluding M. tuberculosis and M. leprae.
• Mycobacterium chelonae (Runyon Group IV) is the most common species in ocular infections.
• These bacteria reside in air and water and can enter via surgical instruments, trauma, or topical steroids.

🔹 LASIK-Associated Challenges

• Infection occurs under the LASIK flap, invisible on superficial exam.
• Specimen collection requires lifting the flap, which patients may resist.
• Diagnosis is delayed due to negative routine cultures, requiring acid-fast staining and special media.
• Delay + steroid use → infection worsens → potential flap necrosis or scarring → corneal transplant

🔹 Treatment

• Early debridement and antimicrobial irrigation is crucial.
• Topical Amikacin or Clarithromycin in high concentrations recommended.
• Flap removal enhances drug penetration and clinical improvement.

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📋 NTM Keratitis Summary Table (English)

CategoryKey Details

Causative Organism	Mycobacterium chelonae (Runyon IV group)
Risk Factors	LASIK, trauma, CL use, steroid drops
Clinical Features	Slow progression, crystalline stromal deposits, sub-flap involvement
Diagnostic Barriers	Mimics DLK, negative routine cultures, needs special media/stains
Treatment Plan	Flap lifting, targeted antimicrobials (Amikacin/Clarithromycin), debridement
Prognosis	Late diagnosis → flap necrosis, scarring, possible full-thickness graft