Repeated corneal crosslinking for progressive keratoconus: efficiency and safety.

Corneal crosslinking (CXL) was first introduced in clinical practice in 2003. Since then, this procedure has been established as the first-line treatment in the management of progressive keratoconus. Over the last years, many different protocols have emerged, each one of them with variable clinical outcomes and safety profile. Progression of keratoconus after primary CXL is very rare, but it has been reported in the literature. This review summarises the existing data on repeated CXL after primary failure, emphasising on clinical efficacy and safety.