Outcomes of Epi-On Collagen Cross-Linkage Procedure Assessed in Progressive Keratoconus Patients

Introduction: Keratoconus is a corneal ectasia that causes astigmatism and reduced vision. Conventional treatment to stop the progression of ectasia involves debridement of corneal epithelium, followed by ultraviolet light and riboflavin drops to reinforce the collagen covalent bonds, called collagen cross-linkage (CXL). Epi-on (epithelium-on) is a modified technique without epithelial debridement and associated complications of pain, infection, and damage to the cornea. However, despite a good safety index and efficacy, Epi-on has not completely replaced the conventional Epi-off (epithelium-off) CXL. We aim to report our five-year experience and outcomes with Epi-on CXLMethods: In this five-year retrospective clinical audit, we included all patients who underwent Epi-on CXL from December 2014 to June 2020 at the Aga Khan University Hospital. Outcomes were based on best-corrected visual acuity (BCVA) and topographic indicators such as keratometry-max (K-max), keratometry mean (K-mean), pachymetry apex (Pachapex), and pachymetry thinnest (Pachthin) performed during pre-CXL clinical visit within one month of the procedure and were compared with the most remote follow up within three years post-CXL. A p-value of