The Antibacterial Efficacy of High-Fluence PACK Cross-Linking Can Be Accelerated

This month the article, “The Antibacterial Efficacy of High-Fluence PACK Cross-Linking Can Be Accelerated,” authored by ELZA’s Nan-Ji Lu et al., explores how photoactivated chromophore for keratitis-corneal cross-linking (PACK-CXL) as a treatment for infectious keratitis can be improved. Infectious keratitis is a common cause of ocular morbidity, can progress rapidly, and can extreme cases, cause the loss of the eye within days. Infectious keratitis is typically treated with antimicrobial agents. However, as antimicrobial resistance increases, it becomes more difficult to find effective treatment options. PACK-CXL involves saturating the cornea with a chromophore (usually riboflavin) and then photoactivating it with ultraviolet-A (UV-A) light. This generates reactive oxygen species, which have several effects, including increasing the stiffness of the cornea, making the cornea more resistant to digestion, as well as directly damaging pathogen cell membranes and nucleic acids. PACK-CXL is effective in killing bacteria and fungi in experiments and has also been effective both alone and in combination with standard-of-care antimicrobial therapy in clinical practice.

The article by Lu et al. reports an in vitro study, conducted to determine whether high-fluence PACK-CXL can be accelerated while still maintaining its antibacterial efficacy. The study found that high-fluence PACK-CXL did indeed decrease the bacterial concentration of several clinically significant bacterial strains, including S. aureusP. aeruginosa, and S. epidermidis. These strains are commonly implicated in bacterial keratitis and contact lens-associated keratitis. Furthermore, the authors found that higher total fluence PACK-CXL protocols led to a corresponding increase in bacterial killing ratio (BKR).

The study further reinforces the concept that high-fluence PACK-CXL can be used as an effective treatment for infectious keratitis, especially as accelerated high-fluence protocols are more convenient and comfortable for patients. Further studies are underway to determine the safety and efficacy of high-fluence accelerated PACK-CXL in clinical practice.


Lu NJ, Koliwer-Brandl H, Gilardoni F, et al. The antibacterial efficacy of high-fluence pack cross-linking can be accelerated. Transl Vis Sci Technol. 2023;12(2):12.

Click here to read the article.

High-Fluence PACK Cross-Linking Can Be Accelerated




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