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Optimizing fluence settings and riboflavin composition for PACK-CXL in antimicrobial efficiency against P aeruginosa and S aureus

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Session Details

Session Title: Cornea Medical

Session Date/Time: Tuesday 16/09/2014 | 14:00-16:00

Paper Time: 15:06

Venue: Capital Hall A

First Author: : O.Richoz SWITZERLAND

Co Author(s): :    F. Hafezi              

Abstract Details


When treating bacterial keratitis, determination of the correct pathogen is often clinically challenging. The benefits of using PACK (Photoactivated chromophore for infectious keratitis)-CXL to treat corneal infections is that the treatment is not pathogen-specific. In an attempt to optimize the treatment parameters, we analyzed the effect of high intensity PACK-CXL on the bacterial killing rate in an in vitro model using Pseudomonas aeruginosa.


Geneva university hospital, ophthalmology department.


The killing rate of a known concentration of bacterias (Pseudomonas aeruginosa and Staphylococcus aureus) 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.


The groups with preservative-free riboflavin showed a pathogen reduction (killing rate) of 2 log units with 18 mW/cm2 and of one log unit with 36 mW/cm2. The groups with riboflavine with preservatives showed a killing rate of 2 log units (98 %) at both irradiation levels.


The P. aeruginosa and S. aureus killing rate is intensity-dependent when using conventional riboflavin and intensity-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.

Financial Interest:

One or more of the authors... has significant investment interest in a company producing, developing or supplying product or procedure presented

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