PACK-CXL: corneal collagen cross-linking for infectious keratitis

Infectious keratitis is one of the leading causes of irreversible vision loss.With the emergence of multidrug-resistant pathogen, despite appropriate diagnosis and antimicrobial treatment, infectious keratitis can still result in corneal opacity and even melting and perforation.Therefore, it is imperative to develop novel treatment for infectious keratitis.More recently, several articles have demonstrated the effectiveness of collagen cross-linking (CXL) in treating infectious keratitis via direct antimicrobial activity and inhibition of corneal enzymatic degradation.In order to highlight the use of CXL for infectious keratitis treatment, a new term was proposed at the 9th CXL congress to rename its use in infections as photoactivated chromophore for infectious keratitis-CXL (PACK-CXL). Based on the current literature, PACK-CXL appears to be effective for bacterial keratitis, especially on inhibiting corneal perforation.The effect was limited for fungal and amoebic keratitis, and maybe aggravative on viral keratitis.In this article, we will review the basic profile, technical operation, prevention of complication of CXL, the principle mechanism of PACK-CXL and its clinical application for bacterial, fungal keratitis, amoebic and viral keratitis.