Corneal collagen crosslinking (CXL) has emerged as a frontline therapy in keratoconus and post-LASIK ectasia. This video lecture series explores the history and current uses of crosslinking, including epithelium-off, transepithelial, and concurrent crosslinking with corneal ring segments (Intacs). In this segment, Dr. Yaron Rabinowitz first compares phototherapeutic keratectomy (PTK) with mechanical epithelial removal prior to CXL. He then offers evidence from his own practice to help clinicians decide when to use Intacs, CXL, or some combination of the two. The primary factors to consider are patient age, progression of disease, and desired outcomes. In general, says Dr. Rabinowitz, Intacs or combined CXL treatment yields better uncorrected visual acuity, Intacs are better at flattening the cornea and improving contact lens tolerance, and CXL is better at halting disease progression.