Crosslinking for progressive keratoconus: is there room for improvement?

Introduction: the review reports the results of photodynamic accelerated crosslinking (ACXL) protocols focusing on the novelties of high fluence pulsed light transepithelial (Epi-On) ACXL treatments. Areas covered: Review covers the outcomes of accelerated crosslinking (ACXL) for all thickness ectatic corneas, including the new epithelium-on (Epi-On) strategies with progressively enhanced fluence, higher riboflavin concentrations and pulsed light irradiation that are considered a promising way forward of photodynamic CXL therapy of Keratoconus (KC), addressing the role of CXL in combination with excimer laser corneal remodeling and lamellar keratoplasty. Literature research is focused on advancements in transepithelial procedures and high fluence accelerated crosslinking treatments looking at CXL plus combined procedures. Expert opinion: Today CXL can be considered to all intents a customized corneal photodynamic therapy (CPDT) of ectasia with different application modalities. ACXL protocols optimized the clinical workflow and patient compliance reducing the time of treatment to 20–25 minutes, adapting fluence, improving oxygen kinetic and riboflavin loading. Standardized protocols for thin corneas improved the issue of thin corneas. High irradiance pulsed light Epi-ON ACXL performed with and without iontophoresis, at air-room oxygenation or adding intraoperative supplemental oxygen, reduced the gap of efficacy with Epi-Off techniques, creating the conditions for transition to the Epi-On.