To determine whether the Peschke PXL-330 system is safe and effective in the treatment of corneal thinning conditions.

Patients with progressive keratoconus, pellucid marginal degeneration, infectious keratitis, or at risk for post-refractive corneal ectasia will be recruited and undergo epithelial-on corneal crosslinking with the Peschke PXL-330 system using pulsed, accelerated energy delivery. Patients will undergo monitoring for 1 year, with serial measurements of corneal topography, visual acuity, intraocular pressure, and visual function questionnaire.

Inclusion Criteria:

Subjects who have one or both eyes that meet criteria 1 & 2 and 1 or more of the following criteria will be considered candidates for this study.

• 12 years of age or older
• Evidence of progressive keratoconus (based on the discretion of the physician as evidenced by an increase in astigmatism, asymmetry, or worsening vision in the last 3 or more months)
• Presence of central or inferior steepening.
• Axial topography consistent with keratoconus
• Presence of one or more findings associated with keratoconus such as:
• Fleischer ring
• Vogt's striae
• Decentered corneal apex
• Munson's sign
• Rizzutti's sign
• Apical Corneal scarring consistent with Bowman's breaks
• Scissoring of the retinoscopic reflex
• Crab-claw appearance on topography
• Steepest keratometry (Kmax) value ≥ 47.20 D
• I-S keratometry difference > 1.5 D on the Pentacam/Galilei/Orbscan/Cassini map or topography map
• Posterior corneal elevation >16 microns
• Thinnest corneal point <485 microns
• AvaGen (Avellino Labs) genetic testing keratoconus risk score of 67 or higher (high risk).
• Signed written informed consent
• Willingness and ability to comply with schedule for follow-up visits
• For 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
• Scleral Lenses
• Investigator Discretion [Discontinuation of scleral lenses not required unless there is clinical evidence of corneal hypoxia (e.g. corneal neovascularization) at time of screening]
• Signed written informed consent
• Willingness and ability to comply with schedule for follow-up visits

Exclusion Criteria (any of the following are reasons for exclusion):

• Eyes classified as either normal or atypical normal on the severity grading scheme.
• Corneal pachymetry at the screening exam that is <330 microns at the thinnest point 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 or active corneal disease (e.g., herpes simplex, herpes zoster keratitis, recurrent erosion syndrome, acanthomeoeba, etc.)
• 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 active medical implants (e.g. cardiac pacemakers)'
• Patients who are aphakic/ pseudophakic

Individual participant data will be stored in a secure location. While summary outcomes data will be provided on request to other researchers and periodically at scientific conferences, protected health information will not.

Randomized at outset