[Anti-infectious cross-linking: when and how? : PACK-CXL as treatment option for infectious keratitis]

Infectious keratitis remains a major cause of blindness worldwide. Conventional antimicrobial treatment is not always sufficient, particularly against drug-resistant pathogens. Photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) offers a promising adjunctive or alternative treatment.

Narrative review based on the current literature and clinical experience, covering mechanisms of action, clinical evidence, protocol selection and practical decision-making criteria for PACK-CXL.

The PACK-CXL acts via three mechanisms: direct killing of pathogens through reactive oxygen species (ROS), increased resistance to protease digestion through steric hindrance and anti-inflammatory effects. Clinical studies demonstrated that adjuvant PACK-CXL shortens the healing time and as monotherapy achieves approximately 89% success in small bacterial ulcers. Higher total radiation doses (high fluence, ≥ 7.2 J/cm²) are more effective than the standard protocol (5.4 J/cm²). For Acanthamoeba keratitis, a sequential dual chromophore strategy (riboflavin/UV followed by Rose bengal/green light) shows promising results.

The use of PACK-CXL enables rapid, largely pathogen-independent treatment of infectious keratitis. Protocol selection should be guided by ulcer size, depth and pathogen type. Accelerated high-fluence protocols are particularly suitable for antimicrobial use.