Photoactivated Chromophore Corneal Collagen Cross-Linking for Infectious Keratitis (PACK-CXL)—A Comprehensive Review of Diagnostic and Prognostic Factors Involved in Therapeutic Indications and Contraindications

Abstract

Infectious keratitis is a severe infection of the eye, which requires urgent care in order to prevent permanent complications. Typical cases are usually diagnosed clinically, whereas severe cases also require additional tools, such as direct microscopy, corneal cultures, molecular techniques, or ophthalmic imaging. The initial treatment is empirical, based on the suspected etiology, and is later adjusted as needed. It ranges from topical administration of active substances to oral drugs, or to complex surgeries in advanced situations. A novel alternative is represented by Photoactivated Chromophore Corneal Collagen Cross-Linking (PACK-CXL), which is widely known as a minimally invasive therapy for corneal degenerations. The purpose of this review is to identify the main diagnostic and prognostic factors which further outline the indications and contraindications of PACK-CXL in infectious keratitis. Given the predominantly positive outcomes in the medical literature, we ponder whether this is a promising treatment modality, which should be further evaluated in a systematic, evidence-based manner in order to develop a clear treatment protocol for successful future results, especially in carefully selected cases.

Staphylococcus aureus and Pseudomonas aeruginosa infectious keratitis: key bacterial mechanisms that mediate pathogenesis and emerging therapeutics

“…However, it has also been appreciated that the free-radicals generated from the combination of ultraviolet-A light and the photosensitizing agent, riboflavin, may have antimicrobial activity as well. Over the past 10 years, PACK-CXL has been used to treat advanced corneal melts, including those with infectious origins, both as a standalone treatment but also in conjunction with traditional antimicrobial therapies with moderate success ( Papaioannou et al., 2016 ; Tabibian et al., 2016 ; Lee et al., 2021 ; Barac et al., 2022 ). While this technology is currently used in cases that have failed conventional treatment, with optimization of both the light source and photosensitizing agent, there may be broader applications in the future.…”

Accelerated high fluence photoactivated chromophore for infectious keratitis—corneal cross-linking (PACK-CXL) at the slit lamp: a pilot study

“…Prompt treatment with topical broad-spectrum antimicrobial eye drops is the standard of care ( Lin et al, 2018 ), and additional interventions such as corneal debridement may be used in some cases. Once the pathogen has been identified, more targeted therapy can be used according to the causative pathogen’s antimicrobial drug sensitivity profile ( Barac et al, 2022 ). However, even with prompt treatment, outcomes are not always favorable due to various factors such as antibiotic resistance, low bacterial isolation rates, limited corneal drug penetration, plus several other predisposing risk factors ( Knyazer et al, 2020 ).…”

The Challenges and Therapeutic Prospects in Eye Disease

“…PACK-CXL offers a potential, less expensive alternative, acting as a primary or adjunctive treatment for infectious keratitis. Barac et al carried out a comprehensive review to identify the main diagnostic and prognostic factors involved in therapeutic indications and contraindications of PACK-CXL in infectious keratitis [ 28 ].…”