Optimizing Fluence Settings and Riboflavin Composition for CXL in Antimicrobial Efficiency Against Pseudomonas Aeruginosa
Narrative Responses:
Purpose
When treating keratitis, determination of the correct pathogen is often clinically challenging. The benefits of using CXL to treat corneal infections is that the treatment is not pathogen-specific. To optimize the treatment parameters, we analyzed the effect of high fluence CXL on the killing rate in an in vitro model.
Methods
The killing rate of a known concentration of bacterias (Pseudomonas aeruginosa) was analyzed for the following conditions: 1) preservative-free riboflavin, with UV-A irradiation @ 18 mW/cm2 for 5 minutes 2) preservative-free riboflavin, with UV-A irradiation @ 36 mW/cm2 for 2.5 minutes 3) riboflavin with preservatives, with UV-A irradiation @ 18 mW/cm2 for 5 minutes 4) riboflavin with preservatives, with UV-A irradiation @ 36 mW/cm2 for 2.5 minutes 5) riboflavin only, no UVA 6) riboflavin with preservatives, no UVA. We used 0.1% riboflavin in all experiments.
Results
The groups with preservative-free riboflavin showed a killing rate of 92 % with 18 mW/cm2 and 22 % with 36 mW/cm2. The groups with riboflavine and preservatives showed a killing rate of 2 logs (98 %) with both fluences.
Conclusion
The P. aeruginosa killing rate is fluence-dependent when using conventional riboflavin and fluence-independent when preservatives are added to the riboflavin solution. These findings will allow the generation of optimized riboflavin solutions for the treatment of bacterial keratitis.