High-Fluence Accelerated Pack-Cxl Using Riboflavin/Uv-A Or Rose Bengal/Green Light To Treat Bacterial Keratitis: An Ex-Vivo Porcine Corneal Infectious Model

Published 2023 - 41st Congress of the ESCRS

Reference: PP06.02 | DOI: 10.82333/jcm3-9n45

Authors: Nanji Lu* ¹ , Hendrik Koliwer-Brandl ² , Mark Hillen ³ , Adrian Egli ² , Farhad Hafezi ⁴

¹Ophthalmology,ELZA Institute,Dietikon,Switzerland;Ophthalmology,University of Antwerp,Antwerp,Belgium; Institute for Medical Microbiology,Zurich,Switzerland, ²Institute for Medical Microbiology,Zurich,Switzerland, ³ELZA Institute,Dietikon,Switzerland, ⁴Ophthalmology,ELZA Institute,Dietikon,Switzerland;Ocular Cell Biology Laboratory,University of Zurich,Zurich,Switzerland

To investigate the effectiveness of high-fluence accelerated photoactivated chromophore for keratitis cross-linking (PACK-CXL) in treating Staphylococcus aureus and Pseudomonas aeruginosa infections in porcine corneas.

Institute for Medical Microbiology, University of Zurich

Ex vivo porcine corneas were assigned to 1 of 8 groups. 6 groups inoculated with 10⁴ CFU of S. aureus or P. aeruginosa and incubated for 24 h. One of two PACK-CXL protocols was applied these groups: riboflavin/UV-A light (30 mW/cm², 8m20s, 15 J/cm²) or rose bengal/green light (15 mW/cm², 16m40s, 15 J/cm²). 2 unirradiated groups and 2 unirradiated infected groups acted as controls. All corneas were incubated at 37ºC for another 24 hours. The corneas were excised and vortexed to release the bacterial cells, which were plated and incubated on agar plates. The amount of colony forming units was then quantified and the bacterial killing ratios (BKR) resulting from different PACK-CXL protocols relative to non-treated controls were calculated.

One hundred and seventeen porcine corneas were included. UV-A light/riboflavin PACK-CXL resulted in median BKRs of 52.8% and 45.8% in S. aureus and P. aeruginosa, respectively, whereas green light/rose bengal PACK-CXL resulted in significantly greater BKRs of 76.7% and 81.0%, respectively (both p-values < 0.01).

Both riboflavin/UV-A and rose bengal/green light high-fluence accelerated PACK-CXL protocols significantly decrease S. aureus and P. aeruginosa bacterial loads. Our data may help develop strain-specific PACK-CXL approaches that could be used alongside the current standard of care.