Transepithelial (Epi-On) Corneal Collagen Crosslinking With Supplemental Oxygen As A Treatment For Patients With Progressive Keratoconus In Oman - One-Year Results

Conventional (Epi-off) corneal collagen cross-linking (CXL) has been the gold standard for the treatment of patients with progressive keratoconus or ectasia.

Epi-on CXL is an alternative to avoid the undesired side effects associated with Epi-off CXL such as delayed epithelial healing, infection & haze, but less efficacy is a major drawback.

Application of transepithelial Riboflavin combined with supplemental Oxygen for Epi-on CXL has shown to give promising results.

The purpose of this study is to assess the one-year outcome of  Epi-on CXL with supplemental Oxygen in patients with progressive keratoconus.

This prospective study is conducted from December 2021 to February 2023 at the MOD-Hospital, which is a tertiary care hospital located in Muscat, the capital of Oman.

50 eyes of 35 patients with progressive keratoconus were subjected to Epi-On CXL with supplemental Oxygen. The procedure was carried out under aseptic preparation and topical anesthesia. Cornea was soaked with transepithelial Riboflavin formulation over 10 minutes period prior to the application of Ultra-Violet (UV) irradiance. 30 mW/cm²   of UV power was applied to deliver a dose of 10 J/cm²  energy in pulse mode. During the UV irradiance, supplemental oxygen is delivered through a goggle to achieve > 90% saturation within the chamber. The follow-up was done over a one-year period and included assessment of uncorrected visual acuity (UCVA), Best corrected visual acuity (BCVA), corneal stromal demarcation line depth, and corneal tomography.

All 50 eyes of 35 patients have included in the assessment and all of them completed a one-year follow-up.

The mean age was 18.55 years and 72.5 % represented males.

Pre-CXL mean K-max was 57.19 diopters and the mean thinnest pachymetry was 451 microns. The mean depth of the corneal demarcation line was 339.4 microns and showed a mean percentage of 70% in corneal penetration.

After one year, the mean UCVA had improved from 0.316 to 0.324 decimals, and the mean BCVA had improved from 0.564 to 0.588 decimals.

The mean K-max had improved to 56.91 diopters.

The mean thinnest pachymetry was 446.34 microns and showed stability over the follow-up period.

No serious adverse effects were noted during the follow-up.

Transepithelial CXL can be done safely & effectively for patients with progressive keratoconus.

Supplemental oxygen, trans-epithelial Riboflavin, and high energy UV have enhanced deeper penetration of crosslinking effect to a desired level in most of the cases in this study.

Our study shows promising results after one year in stabilizing progressive keratoconus.

Long-term data will give us a better understanding of the efficacy and head-to-head trials are needed to compare the efficacy of Epi-on over Epi-off crosslinking.