Density, light scatter, and spectral transmission of a scarred human cornea

Purpose To determine whether high-fluence photoactivated chromophore for keratitis cross-linking (PACK-CXL) can be accelerated. Methods Solutions of Staphylococcus aureus and Pseudomonas aeruginosa with 0.1% riboflavin were prepared and exposed to 365 nm ultraviolet (UV)-A irradiation of intensities and fluences from 9 to 30 mW/cm 2 and from 5.4 to 15.0 J/cm 2 , respectively, representing nine different accelerated PACK-CXL protocols. Irradiated solutions and unirradiated controls were diluted, plated, and inoculated on agar plates so that the bacterial killing ratios (BKR) could be calculated. Additionally, strains of Achromobacter xylosoxidans, Staphylococcus epidermidis , and Stenotrophomonas maltophilia were exposed to a single accelerated PACK-CXL protocol (intensity: 30 mW/cm 2 , total fluence: 15.0 J/cm 2 ). Results With total fluences of 5.4, 10.0, and 15.0 J/cm 2 , the range of mean BKR for S. aureus was 45.78% to 50.91%, 84.13% to 88.16%, and 97.50% to 99.90%, respectively; the mean BKR for P. aeruginosa was 69.09% to 70.86%, 75.37% to 77.93%, and 82.27% to 91.44%, respectively. The mean BKR was 41.97% for A. xylosoxidans , 65.38% for S. epidermidis , and 78.04% for S. maltophilia for the accelerated PACK-CXL protocol (30 mW/cm 2 , 15 J/cm 2 ). Conclusions The BKR of high-fluence PACK-CXL protocols can be accelerated while maintaining a high, but species-dependent, BKR. The Bunsen to Roscoe law is respected in fluences up to 10 J/cm 2 in S. aureus and P. aeruginosa , whereas fluences above 10 J/cm 2 show strain dependence. Translational Relevance The high-fluence PACK-CXL protocols can be accelerated in clinical practice while maintaining high levels of BKR.

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“…This factor should further lower the potential risk of endothelial cell damage caused by PACK-CXL with a total fluence of 15 J/cm 2 . 24 …”

Section: Discussionmentioning

confidence: 99%