Antibacterial efficacy of accelerated photoactivated chromophore for keratitis-corneal collagen cross-linking (PACK-CXL).

Abstract

PURPOSE:

To investigate whether optimized photoactivated chromophore for keratitis-corneal collagen cross-linking (PACK-CXL) treatment settings allow accelerating treatment while maintaining antibacterial efficacy.

METHODS:

Staphylococcus aureus and Pseudomonas aeruginosa strains were irradiated with ultraviolet-A light of equal fluence but different intensity settings (18 mW/cm² for 5 minutes and 36 mW/cm² for 2.5 minutes). The killing rate was determined by comparing the number of colony-forming units between cross-linked specimens and non-irradiated controls. The potential additional effect of 0.001% benzalkonium chloride was also investigated.

RESULTS:

The killing rates for Staphylococcus aureus were 92.5% ± 5.5% (5 minutes at 18 mW/cm²) and 94.4% ± 2.9% (2.5 minutes at 36 mW/cm²). For Pseudomonas aeruginosa, the killing rates were 93.2% ± 8.3% (5 minutes at 18 mW/cm²) and 92.9% ± 5.0% (2.5 minutes at 36 mW/cm²). The presence of benzalkonium chloride in the riboflavin solution did not increase the killing rate significantly.

CONCLUSIONS:

The antibacterial efficacy of PACK-CXL follows the Bunsen-Roscoe law of reciprocity and can be maintained even when the irradiation intensity is considerably increased. These optimized settings may allow a shortened treatment time in the future for PACK-CXL and thus help facilitate the transition from the operating room to the slit lamp for treatment.

• Authors: Olivier Richoz, Sabine Kling, Florence Hoogewoud, Arthur Hammer, David Tabibian, Patrice Francois, Jacques Schrenzel, Farhad Hafezi
• Journal: Journal of refractive surgery (Thorofare, N.J. : 1995) (J Refract Surg) Vol. 30 Issue 12 Pg. 850-4 (Dec 2014) ISSN: 1081-597X [Print] United States
• PMID: 25437485 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright 2014, SLACK Incorporated.

Chemical References

• Anti-Bacterial Agents
• Benzalkonium Compounds
• Photosensitizing Agents
• Riboflavin

Topics

• Animals
• Anti-Bacterial Agents (pharmacology, therapeutic use)
• Benzalkonium Compounds (pharmacology)
• Colony Count, Microbial
• Corneal Ulcer (drug therapy, microbiology)
• Eye Infections, Bacterial (drug therapy, microbiology)
• Photosensitizing Agents (therapeutic use)
• Pseudomonas Infections (drug therapy, microbiology)
• Pseudomonas aeruginosa (drug effects, isolation & purification, radiation effects)
• Riboflavin (pharmacology, therapeutic use)
• Staphylococcal Infections (drug therapy, microbiology)
• Staphylococcus aureus (drug effects, isolation & purification, radiation effects)
• Swine
• Ultraviolet Rays