Corneal Collagen Crosslinking for Keratoconus and Ectasia Using Riboflavin/Dextran or Riboflavin/Methylcellulose

Inclusion Criteria: * 12 years of age or older * Having a diagnosis of keratoconus or corneal ectasia after corneal refractive surgery * Presence of central or inferior steepening on the Pentacam map * Axial topography consistent with keratoconus or post-surgical corneal ectasia * Contact lens wearers only: removal of contact lens for the required period of 1 week prior to the screening refraction * Signed written informed consent * Willingness and ability to comply with schedule for follow-up visits Exclusion Criteria: * Eyes classified as either normal, atypical normal, or keratoconus suspect on the severity grading scheme * Corneal pachymetry less than or equal to 300 microns at the thinnest point measured by Pentacam in the eye(s) to be treated * Previous ocular condition (other than refractive error) in the eye(s) to be treated that may predispose the eye for future complications, for example: History of corneal disease (e.g., herpes simplex, herpes zoster keratitis, recurrent erosion syndrome, corneal melt, corneal dystrophy, etc.) Clinically significant corneal scarring in the CXL treatment zone * A history of chemical injury or delayed epithelial healing in the eye(s) to be treated * Pregnancy (including plan to become pregnant) or lactation during the course of the study * A known sensitivity to study medications * Patients with nystagmus or any other condition that would prevent a steady gaze during the CXL treatment or other diagnostic tests * Patients with a current condition that, in the investigator's opinion, would interfere with or prolong epithelial healing