Epi-on Versus Epi-off Accelerate Corneal CXL for Progressive Keratoconus: 1-Year Follow-up
Purpose
To evaluate and compare the safety and efficacy of accelerate corneal collagen crosslinking (CXL) epi-on versus epi-off in progressive keratoconus.
Methods
This prospective and comparative study included 60 eyes with progressive keratoconus. 30 eyes underwent transepithelial CXL (epi-on), and 30 eyes conventional CXL removing the epithelium (epi-off); between July 2013 and July 2014. The solution for epi-on was TE-riboflavin and for epi-off was isotonic M-riboflavin (Peschke Ltd, Germany); for both procedures the time of impregnation was 30 minutes and Ultraviolet-A treatment was performed with CCL-VARIO (Peschke Ltd, Germany) with 5 minutes of irradiation (18mW). Scheimpflug imaging parameters where evaluated at pre and postoperatively at 1, 6 and 12 months; as the demarcation line using AS- OCT (anterior segment optical coherence tomography).
Results
Mean crosslinking depth in epi-on group using AS-OCT at the center of the cornea was 243.05 um, compared to 270.19 um in the epi-off group, with statistically significant difference between groups (p < .001). Mean maximum posterior elevation decreased from 28.14 um to 27.00 um (p = 0.009) in the epi-on group and from 24.14 um to 22.55 um in the epi-off group (p = 0.034) at 1 year, with no statistically significant difference between groups (p = 0.310). Mean decrease in the maximum keratometry was 0.71 Diopters (D) in the epi-on compared with 1.42D in the epi-off group (p =0.05).
Conclusion
Both accelerate crosslinking epi-on and epi-off procedures are safe and efficacy to stop the progression of the keratoconus. AS-OCT images showed that epi-off CXL had deeper demarcation line compared with epi-on CXL.