Corneal cross-linking may have application in infective keratitis

Corneal cross-linking has been popularly used to prevent progression of keratoconus and corneal ectasia. The procedure is based on using riboflavin as a photosensitizer, which generates reactive oxygen species when activated by ultraviolet A at 365 nm. It induces a photochemical reaction that forms covalent bonds or cross-links in the corneal stroma. In the last decade, it has been introduced in keratitis and infective corneal ulcers that are resistant to drugs. With the rising incidence of multidrug resistance, corneal infections are increasing and devastating consequences are faced in aggressive microbial infections. Corneal cross-linking has provided a significant contribution in controlling the pathogenesis of the infections.In 1965, Tsugita and colleagues noted that riboflavin, when subjected to either visible or UV light, could inactivate the RNA of tobacco mosaic virus. Spoerl and colleagues proved by in vitro study that a cross-linked cornea is more resistant to collagenases enzymatic activity than the normal or diseased cornea. Although there have been studies showing the antibacterial activity of riboflavin with UV light in vitro, the pilot study on human eyes was performed by Makdoumi and colleagues. They performed a pilot study to investigate the photochemical interaction used in corneal cross-linking as the primary therapy for bacterial keratitis. For microbial keratitis, Hafezi and colleagues named the therapy photoactivated chromophore for keratitis corneal cross-linking, or PACK-CXL.