ESCRS - PP11.17 - The Antibacterial Efficacy Of High-Fluence Pack Cross-Linking Can Be Accelerated

The Antibacterial Efficacy Of High-Fluence Pack Cross-Linking Can Be Accelerated

Published 2022 - 40th Congress of the ESCRS

Reference: PP11.17 | Type: ESCRS 2022 - Posters | DOI: 10.82333/desy-k604

Authors: Nanji Lu* 1 , Hendrik Koliwer-Brandl 2 , Emilio Torres-Netto 3 , Mark Hillen 3 , Boris Knyazer 4 , Nikki Hafezi 3 , Reinhard Zbinden 2 , Farhad Hafezi 3

1ELZA Institute,Zurich,Switzerland;University of Antwerp,Antwerpen,Belgium, 2Institute of Medical Microbiology, University of Zurich,Zurich,Switzerland, 3ELZA Institute,Zurich,Switzerland, 4Ophthalmology Department,Soroka University Medical Center and Faculty of Health Sciences, Ben-Gurion University of the Negev,Beer-Sheva,Israel

Purpose

To determine whether high-fluence photoactivated chromophore for keratitis cross-linking (PACK-CXL) can be accelerated.

Setting

The Ocular Cell Biology Group, Center for Applied Biotechnology and Molecular Medicine and the Institute of Medical Microbiology, University of Zurich, Switzerland.

Methods

Solutions of a clinical strain of Staphylococcus aureus obtained from an infected eye and 0.1% riboflavin were prepared and irradiated at 365 nm ultraviolet (UV)-A using intensities and fluences ranging from 9 to 30 mW/cm2 and 5.4 to 15 J/cm2, respectively, representing nine different accelerated PACK-CXL protocols. Irradiated and unirradiated bacterial solutions were plated and inoculated on agar plates. The number of colony forming units (CFU) was counted and bacterial killing ratios (BKRs) were calculated.

Results

The mean BKR for Staphylococcus aureus with 0.1% riboflavin solutions after an irradiation applying total fluences of 5.4 J/cm2, 10J/cm2, and 15 J/cm2 using accelerated protocols were 45.78%-50.20%, 80.01%-84.13%, and 97.21%-99.91%, respectively. As controls without riboflavin, the corresponding mean BKR were 15.59%-18.07%, 24.59%-43.19%, and 60.68%-69.09%, respectively.

Conclusions

Compared to standard PACK-CXL protocol, accelerated high-fluence protocols could achieve similarly high levels of BKR, indicating that the Bunsen-Roscoe law of reciprocity is respected to the antibacterial effects of PACK-CXL. Further optimization of technical settings and the use of different enhancers may help reducing bacterial corneal infections by accelerated PACK-CXL.