A safe and effective method for thin cornea cross-linking

The mechanical properties of the collagen matrix determine the corneal regularity. Thus, corneal thinning, cone-like protrusion, and loss of corneal astigmatism characterize corneal ecstatic diseases, including keratoconus and post-LASIK ectasia. Currently, riboflavin (RF)/ultraviolet A (UVA) based corneal collagen cross-linking (CXL) is commonly used in clinics to stiffen cornea and halt disease progression in patients. However, due to tissue damage, especially irreversible endothelium loss, standard RF/UVA protocol is only allowed in eyes with corneal thickness over 400 m after epithelium debridement. Thus, lots of patients with thin cornea have limited therapeutic options. Here, we introduced a new strategy to cross-link cornea collagens using synthesized photo-initiators lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) and visible blue light (BL). The LAP/BL protocol could effectively increase corneal stiffness, similar to the RF/UVA protocol in both porcine and rabbit cornea. When the LAP/BL protocol was used, both epithelial wound healing, stromal cell repopulation, and corneal edema recovery rates were accelerated compared with the RF/UVA protocol. More importantly, as BL is used instead of UVA, corneal endothelium was mostly preserved in both rabbit and mouse models even when cornea thickness was as thin as 100 m. In summary, we propose that the LAP/BL protocol is a safe and effective choice for thin cornea CXL.