Corneal stromal demarcation line depth after corneal collagen cross-linking following conventional versus customized corneal epithelial debridement

Abstract

Aim of the Study: Using anterior segment optical coherence tomography (AS-OCT) to compare the depth of corneal demarcation line (DL) after corneal collagen cross-linking (CXL) with subtotal versus customized corneal epithelium debridement. Design: Prospective multi centric case-control study. Materials and Methods: The study enrolled 18 patients with bilateral progressive keratoconus. Both eyes treated by CXL using 3 mW/cm2 / 30 minutes setting. One eye with subtotal epithelial debridement ( about 9 mm diameter) and the contralateral eye with customized debridement ( approximately 1 mm single horizontal scratch ). One month postoperatively, patients had AS-OCT imaging to detect and measure the depth of DL. Results: Patients’ age mean was 25.17 years +/- 4.81 SD . Epithelial healing completed with in 3-7 days in conventional treatment group and demarcation line was evident in 16 eyes ( 89% ) with a mean depth of 290.31 micro m while in customized epi-off treatment group, the epithelial healing lasted less than 24 hours and DL was detectable in 10 patients ( 55.5 % ) with a mean DL depth of 221 micro m with a statistically significant difference ( p < 0.05 ) Subjective postoperative pain graded as “moderate to severe” in about 77% of eyes underwent 9 mm epi-off CXL compared with 55% of those with customized treatment. Conclusions: Although the DL if found in majority cases, but the shallow location in customized corneal debridement cases questioned the efficacy of this technique despite the quick re-epithelialization and less postoperative pain that accompanied it.