Corneal Stromal Demarcation Line Depth after Corneal Collagen Cross-Linking Using Customized vs. Conventional Corneal Epithelial Debridement

Abstract

Aim of the Study: Compare the corneal demarcation line (DL) depth after corneal collagen cross-linking (CXL) with subtotal versus customized corneal epithelium debridement using anterior segment optical coherence tomography (AS-OCT).
Design: Prospective case-control study.
Materials and Methods: The study enrolled 18 patients with bilateral progressive keratoconus. Both eyes treated by CXL using a 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 central 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 within 3-7 days in the conventional treatment group and demarcation line was evident in 16 eyes (89%) with a mean depth of 290.31 μm while in the customized debridement 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 μm 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 debridement group.
Conclusions: Although the DL if found in the 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.