Accelerated Corneal Collagen Crosslinking for Keratoconus and Ectasia Using Pulse or Continuous UV-A Light

This is a prospective, single-site study to analyze the use of continuous vs pulsed UVA light after removal of the epithelium for the collagen crosslinking procedure for keratoconus and post-refractive corneal ectasia. In the standard crosslinking treatment, the cornea is treated with a continuous UVA light treatment with a power of 3mW/cm2 for 30 minutes. CXL treatment can potentially be performed in a shorter period of time by increasing the power of the UVA light and decreasing the exposure time, while maintaining the same total energy delivered to the cornea. This study will compare the efficacy and safety of accelerated crosslinking using either a continuous or pulsed UVA treatment. One group will be randomized to be treated with 12mW/cm2 of continuous UVA light treatment for 7.5 minutes and the other group will be treated with 12mW/cm2 of pulsed UVA light treatment for 15 minutes. The primary efficacy parameter that will be evaluated over time is maximum keratometry (Kmax) in the randomized eyes for each treatment group. The secondary efficacy parameter is to determine if the two treatment groups are equivalent in their mean Kmax change at 6 months after treatment compared with baseline.