In‐vivo corneal collagen crosslinking using ruthenium and visible light

Aims/Purpose: Corneal collagen cross‐linking (CXL) treatment is widely applied to halt the progression of ectatic diseases such as keratoconus. Unfortunately, the standard CXL procedure based on riboflavin and UV‐A light can only be applied to cornea thicker than 400 μm and results in frequent complications, such as corneal haze and endothelial damage [1]. This study investigates a new CXL procedure based on ruthenium, which is a water‐soluble photoinitiator and visible light (430 nm) in vivo. Methods: For the CXL procedure, tris(bipyridine)ruthenium(II) ([Ru(bpy)3]2+), an SPS solution was applied to the rat's cornea and exposed to blue light. After the crosslinking procedure, observations were made for corneal opacity, corneal neovascularization, limbal neovascularization and corneal epithelial damage. Furthermore, the corneas were isolated for histopathological examination, cell viability and SEM analysis, and the results were compared with the conventional riboflavin/UV‐A crosslinking approach. Results: Crosslinked corneas with ruthenium‐based CXL approach showed significantly improved scoring in corneal opacity, corneal neovascularization, limbal neovascularization and corneal wound healing as compared to the standard riboflavin and UVA‐based CXL procedure. Histopathological analysis and cell viability revealed ruthenium to be nontoxic and create more bonds between collagen fibrils when observed under scanning electron microscopy. Conclusions: In this in vivo study, the ruthenium and visible light‐based crosslinking approach proved to be non‐toxic and a faster alternative to the conventional riboflavin and UVA‐based CXL method. We foresee that ruthenium visible light‐based crosslinking treatment could potentially change the treatment modality in keratoconus patients in a clinical setting. Funding Information: This work is supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK) under GrantARDEB‐219S349. References: 1. Gulzar, A., et al., Ruthenium‐induced corneal collagen crosslinking under visible light. Acta Biomater, 2022. 147: p. 198–208.