To evaluate two different techniques of cross linking: standard epithelium off (CXL epi off) versus trans-epithelial (CXL epi on) cross linking in patient with progressive keratoconus.

The aim of the study is to evaluate two different techniques of cross linking: standard epithelium off (CXL epi off) versus trans-epithelial (CXL epi on) cross linking in patient with progressive keratoconus.

Forty eyes from 32 patients with progressive keratoconus were prospectively enrolled from June 2014 to June 2015 in this non-blinded, randomized comparative study. Twenty eyes were treated by CXL epi off and 20 by CLX epi on, randomly assigned and followed for 2 years. All patients underwent a complete ophthalmologic testing that included uncorrected and best corrected visual acuity, central and peripheral corneal thickness, corneal astigmatism, simulated maximum, minimum, and average keratometry, corneal confocal microscopy, Schirmer I and break-up time (BUT) tests, and the Ocular Surface Disease Index. Intra-and postoperative complications were recorded. The solution used for CXL epi off comprised riboflavin 0.1% and dextran 20.0% (Ricrolin), whereas the solution for CXL epi on (Ricrolin, TE) comprised riboflavin 0.1%, dextran 15.0%, trometamol (Tris), and ethylene-diamine-tetra-acetic acid. Ultraviolet-A treatment was performed with UV-X System at 3 mW/cm2.

Inclusion Criteria:

• patients with evolving keratoconus
• aged between 18 and 40 years
• no evidence of corneal scarring

Exclusion Criteria:

• patients with central and paracentral corneal opacities
• Vogt's striae
• previous intraocular surgery
• history of herpetic keratitis
• history of severe dry eye
• concomitant autoimmune diseases.

Data will be made available once the studies results will be published