Corneal Collagen Cross-Linking (CXL) Performed With "Epi-ON" Versus "Epi-OFF" in Eyes With Keratoconus and Other Corneal Ectatic Disorders

Inclusion Criteria: 1. Be at least 12 years of age or older, male or female, of any race. 2. Having a diagnosis of keratoconus or other corneal ectatic disorder. 3. Presence of central or inferior steepening on the topography map. 4. Axial topography consistent with keratoconus or other corneal ectatic disorder. 5. For eyes diagnosed with keratoconus, presence of one or more slit lamp findings associated with keratoconus, such as: 1. Scissoring of the retinoscopic reflex 2. Fleischer ring 3. Vogt striae 4. Corneal thinning e .Corneal scarring 6. BSCVA 20/20 or worse. 7. Subject is willing to have CXL performed by the Epi-OFF or Epi-ON techniques. 8. Provide written informed consent and a signed HIPPA form. Pediatric subjects less than 14 years of age must sign an assent and a parent or legal guardian must sign an informed consent. 9. Willingness and ability to follow all instructions and comply with schedule for follow-up visits. 10. If female and capable of becoming pregnant, must not be lactating or pregnant and must agree to use a medically acceptable form of birth control for at least one week prior to the treatment visit and to continue o one month following treatment. Exclusion Criteria: 1. One of the randomized CXL techniques (Epi-OFF or Epi-ON) is contraindicated or, in the investigator's clinical judgment, is not able to be performed in the study eye. 2. Study eye keratoconus severity is classified as being normal or atypical normal based on the OPD-Scan III keratoconus classification indices. 3. A history of previous corneal transplant in the study eye. 4. A history of prior CXL in the study eye. 5. Corneal pachymetry \< 375 microns at the thinnest point as measured by ultrasound pachymetry in the study eye before epithelium removal. \[NOTE: Eyes with corneal pachymetry between \<375 microns and 325 microns may be enrolled in the compassionate use group.\] 6. Presence of Intacs or corneal rings or segments in the study eye. 7. Previous ocular condition (other than refractive error) in the eye(s) to be treated that may predispose the eye for future complications or prevent the possibility of improved vision, for example: 1. History of corneal disease (e.g., herpes simplex, herpes zoster keratitis, recurrent erosion syndrome, corneal melt, or corneal dystrophy, etc.) 2. Clinically significant corneal scarring in the treatment zone unrelated to keratoconus. 8. Eyes which are aphakic. 9. Eyes which are pseudophakic and do not have a UV blocking lens implanted. 10. A known contraindication, sensitivity, or allergy to the test article or its components or to study medications. 11. Nystagmus or any other condition that would prevent a steady gaze during the cross-linking treatment or other diagnostic tests. 12. If female, pregnant, nursing or planning a pregnancy, or having a positive urine pregnancy test prior to the randomization of, or treatment of, either eye during the course of the study. 13. A condition that, in the investigator's opinion, would interfere with or prolong epithelial healing, including a history of chemical injury or delayed epithelial healing in the study eye. 14. Presence or history or any other condition or finding that, in the investigator's opinion, makes the patient unsuitable as a candidate for cross-linking or study participation or may confound the outcome of the study.