Study is testing the efficacy of treating corneal thinning conditions with Vitamin B2 (Riboflavin) and the application on UV Light.

Corneal thinning conditions, i.e. keratoconus or ectasia, weaken the cornea which then causes the front of the eye to bulge out. This results in distorted vision and could eventually result in the need for a cornea transplant. This study proposes to conclude that saturating the cornea with vitamin B2 (Riboflavin) and then applying 365nm wavelength of Ultra Violet Light will result in the various layers of corneal tissue linking together. This cross linking results in a stronger cornea which is designed to halt the progression of keratoconus or ectasia. This treatment is already being successfully used in Europe.

Inclusion Criteria:

• Presence of central or inferior corneal steepening
• Axial topography consistent with keratoconus, post-surgical ectasia, or pellucid marginal degeneration
• Presence of one or more findings associated with keratoconus or pellucid marginal degeneration, such as:
• Fleischer ring
• Vogt's striae
• Decentered corneal apex
• Munson's sign
• Rizutti's sign
• Apical corneal scarring consistent with Bowman's breaks
• Scissoring of the retinoscopic reflex
• Crab-claw appearance on topography
• Steepest keratometry (Kmax) value > or = 47.20 D
• I-S keratometry difference > 1.5 D on the Orbscan map
• Posterior corneal elevation > 16 microns
• Thinnest corneal point < 485 microns
• Post LASIK/PRK stromal ablation depth < 300 microns or expected keratometry > 47.2 D, or post-PRK/SMILE in keratoconus suspect eyes
• Bacterial or fungal corneal keratitis persistent and not responding despite > 2 weeks of standard antimicrobial therapy or with rapid progression of corneal thinning, with loss of > 25% corneal thickness
• Contact Lens Wearers Only:
• Removal of contact lenses for the required period of time prior to the screening refraction:

Contact Lens Type Minimum Discontinuation Time Soft 1 Week Soft Extended Wear 2 Weeks Soft Toric 3 Weeks Rigid Gas Permeable 2 Weeks per decade of wear

• Signed written informed consent
• Willingness and ability to comply with schedule for follow-up visits

Exclusion Criteria:

• Eyes classified as either normal or atypical normal on the severity grading scheme

• Corneal pachymetry at the screening exam that is < 400 microns at the thinnest point in the eye(s) to be treated when the transepithelial (isotonic) riboflavin solution alone will be used or < 300 microns when the hypotonic riboflavin will be used.

• Previous ocular condition (other than refractive error) in the eye(s) to be treated that may predispose the eye for future complications, for example:

  1. History of or active corneal disease (e.g., herpes simplex, herpes zoster keratitis, recurrent erosion syndrome, acanthamoeba, etc.)
  2. Clinically significant corneal scarring in the CXL treatment zone that is not related to keratoconus or, in the investigator's opinion, will interfere with the cross linking procedure

• 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 physician's opinion, would interfere with or prolong epithelial healing

Unidentifiable patient data and pre- and post-op results will be shared.