PACK-CXL: defining CXL for infectious keratitis.

THE CONCEPT OF CXL In 1998, the proof-of-principle for corneal collagen cross-linking (CXL) was born from such a “simple” concept. Combining ultraviolet-A light and a chromophore (vitamin B2, riboflavin), the cornea could be stiffened within a mere half hour and progressive thinning diseases such as keratoconus could be halted.1,2 Although still considered a relatively new concept, CXL is now in clinical use worldwide. Cross-links in the cornea are not a technique, but rather a physiological principle of all connective tissue. This might explain the enormous versatility of the method of CXL: soon after the proof-of-concept in progressive keratoconus, additional indications were established. These include CXL for postoperative ectasia, CXL for bullous keratopathy, CXL in combination with refractive laser procedures (CXL-Plus), and, most interestingly, CXL for infectious keratitis.3-12