Evaluating the Safety and Efficacy of the KXL System for Corneal Collagen Cross-Linking in Eyes Having Keratoconus

The objectives of this study are to evaluate the safety of and efficacy of the KXL system with vibeX Rapid (Riboflavin Ophthalmic Solution) for Corneal Collagen Cross-Linking in eyes having:

1. Keratoconus (KC) ,
2. Post LASIK ectasia (PLEc)

KC and Plec eyes Group 1 (non-randomised controlled)

Eyes will be assigned into 2 groups:

* Treatment eyes group with KXL
* Control eyes group (fellow eye) The Treatment eyes will be cross linked with the KXL system and the vibeX Rapid Riboflavin, while the control eyes will not receive any treatment.

The safety and efficacy endpoints will be evaluated and compared between the Treatment eye group and the Control eye group.

After 6 months of follow up the KC and PLEc subjects will be offered to treat the control eyes if indicated.

Group 2 (non-randomised controlled combined treatment)

Eyes will be assigned into 2 groups:

* Treatment group with simultaneous KXL and topography-guided transepithelial photorefractive keratectomy(PRK)
* Control eyes group (fellow eye) The Treatment eyes will undergo simultaneous topography-guided PRK and be cross linked with the KXL system and the vibeX Rapid Riboflavin, while the control eyes will not receive any treatment.

The safety and efficacy endpoints will be evaluated and compared between the Treatment eye group and the Control eye group.

After 6 months of follow up the KC and PLEc subjects will be offered to treat the control eyes if indicated.

The concentrations of Riboflavin Ophthalmic Solution will be tested - 0.1% Riboflavin ophthalmic solution

KC Eyes will be irradiated at 30mW/cm2 for 4 minutes continuous treatment or 8 minutes pulse treatment: 1 second on 1 second off.

PLEc Eyes will be irradiated at 30mW/cm2 for 4 minutes continuous treatment or 8 minutes pulse treatment: 1 second on 1 second off..

Eligibility Criteria:
Inclusion Criteria:

1. Age Limit for for keratoconus and Plec:18 years
2. Sign the informed consent.
3. Willingness and ability to follow all instructions and comply with schedule for follow-up visits;
4. Contact Lens Wearers Only:

   Minimum of 3 days
5. For KC subjects:

   1. Axial topography consistent with keratoconus(Pentacam )
   2. Presence of central or inferior steepening on the Pentacam map;
   3. Steepest keratometry (Kmax) value ≥ 47.00 D;
   4. May have corneal scarring up to and including CLEK grade 4.0 (any scarring up to a dense/opaque stromal scar consistent with KC)
   5. Keratoconus progressing over time ( evidenced by topography changes, visual acuity or refractive changes)
6. For PLEc subjects:

   1. Having a diagnosis of corneal ectasia after corneal refractive surgery (e.g., LASIK, PRK, epi-LASIK,LASEK,)
   2. Presence of central or inferior steepening on the Pentacam map.
   3. Axial topography consistent with corneal ectasia

Exclusion Criteria:

1. Contraindications, sensitivity or known allergy to the use of the test article(s) or their components;
2. If female, be pregnant, nursing or planning a pregnancy or have a positive urine pregnancy test at Visit 2 prior to randomization or during the course of the study;
3. For KC and PLEc subjects, corneal pachymetry that is \< 400microns prior to epithelial debridement at the thinnest point measured by Pentacam in the eye to be treated;
4. A history of chemical injury or delayed epithelial healing in the eye(s) to be treated;
5. Patients with nystagmus or any other condition that would prevent a steady gaze during the treatment or other diagnostic tests;
6. Patients with a current condition that, in the investigator's opinion, would interfere with or prolong epithelial healing;
7. Taking Vitamin C (ascorbic acid) supplements within 1 week of the cross-linking treatment,retinoic acid within 6 months of treatment
8. Previous ocular condition (other than refractive error) in the eye to be treated that may predispose the eye for future complications. For example:

   8.1. History of corneal disease (e.g., herpes simplex, herpes zoster keratitis, recurrent erosion syndrome, corneal melt, corneal dystrophy, etc.); 8.2. Clinically significant corneal scarring in the cross-linking treatment zone or in the investigator's opinion, will interfere with the cross-linking procedure;
9. For KC subjects 9.1. Eyes which are aphakic; 9.2. Eyes that have the maximum corneal curvature (Kmax), as identified and measured by Pentacam, outside of the central 5mm zone; Note: In addition, the Investigator may exclude or discontinue any subject for any sound medical reason.