Corneal Collagen Cross-Linking for Corneal Ectasias

Abstract

The aim of this chapter is to review the published literature on corneal collagen cross-linking (CXL). Emphasis has been placed on seminal publications, systemic reviews, meta-analyses and randomized controlled trials. Where such evidence does not exist, large series cohort studies, case-controlled studies and case series with follow-up greater than 12 months were included. Riboflavin/Ultraviolet A (UVA) corneal collagen cross-linking (CXL) is the first therapeutic intervention capable of arresting the progression of ectatic disorders of the cornea. In addition, the majority of investigators report significant improvements in visual, keratometric and topographic measurements 12 months after surgery. Its precise mode of action at a molecular level has not been fully determined. Follow-up is limited to 5–10 years but suggests sustained stability and enhancement in corneal shape with time. Virtually all published long-term data and comparative studies are with epithelium-off techniques. Epithelium-on CXL investigations suggest some efficacy but less than with the epithelium-off treatments and long-term data are not available. Accelerated techniques with higher UVA fluencies and shorter treatments times are the subject of current investigation, with some studies suggesting reduced efficacy compared to the standard 3 milli-watt per square centimetre (mW/cm2) for 30 min irradiation procedure. Research into other CXL methodologies is being undertaken.