Effectiveness of Epithelium-on Corneal Collagen CXL in Treating Corneal Ectasia
Purpose
The purpose of the study is to evaluate the effectiveness of corneal collagen cross-linking (CXL) in increasing corneal collagen stability using an epithelium-on (epi-on) technique compared to the more established epithelium-off (epi-off) method in patients with keratoconus and post-keratorefractive ectasia.
Methods
Retrospective cohort. Patients with keratoconus or post keratorefractive surgery ectasia who had undergone either epi-off or epi-on corneal collagen crosslinking at a private practice from May 2008 to May 2014 were eligible for inclusion. The Dresden protocol was followed for epi-off crosslinking patients. Epi-on patients received 20-minute corneal applications of a riboflavin saturated merocel sponge, followed by Ultraviolet A light exposure (3mW/cm2 to 4mW/cm2) for 30 minutes. All patients were examined after the procedures on day 1, month 3, and month 6-9. Outcome measures collected include pre- and postoperative uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), and change in corneal topography, manifest refraction (MR), keratometry, and Scheimpflug tomography Kmax values.
Results
A total of 240 eyes have been crosslinked using the epi-on technique. A preliminary analysis at 1, 3, 6, 12, and 24-months follow-up has been performed to date. The mean change in Kmax values for the epi-on sub-cohort vs preoperative measures was not statistically significant. Data for 1, 3, 6, 12, 18 and 24 months will be presented for epi-off vs epi on cohorts including pre- and postoperative BSCVA and changes in MR, keratometry and Kmax values. Complication rates by crosslinking technique will also be reported.
Conclusion
Preliminary data suggests epithelium on corneal collage crosslinking is effective in stabilizing corneal changes in patients with keratoconus and post-LASIK ectasia. Epithelium-on crosslinking may offer advantages over epithelium-off crosslinking in terms of quicker visual recovery and lower postoperative complication rates.