Demarcation Line Evaluation of Iontophoresis-Assisted Transepithelial Corneal Collagen Cross-linking for Keratoconus

PURPOSE: To evaluate the visualization and depth of the demarcation line with anterior segment optical coherence tomography (AS-OCT) after iontophoresis-assisted transepithelial corneal collagen cross-linking (CXL). METHODS: This prospective, consecutive, single center, non-randomized clinical study involved 15 eyes of 12 patients with keratoconus who underwent an AS-OCT scan (Spectralis; Heidelberg Engineering, Inc., Carlsbad, CA) to search for a demarcation line and its depth at 1 month after iontophoresis-assisted transepithelial CXL. AS-OCT scan measurements were performed by two independent examiners. RESULTS: No intraoperative or postoperative complications were observed. Kappa coefficient estimation for operator agreement in demarcation line visualization (whether it was visualized) was 70.6%. The corneal stromal demarcation line was identified in 9 eyes (60%) by both examiners. Mean depth of the corneal stromal demarcation line was 246.67 ± 50.72 µ m (range: 183 to 339 µ m) for the first examiner and 241.89 ± 62.52 µ m (range: 163 to 358 µ m) for the second examiner. There were no statistically significant differences for the measurements of the paired comparisons between the two examiners ( P = .61). The Pearson correlation coefficient between the measurements was 0.910. CONCLUSIONS: Iontophoresis-assisted transepithelial CXL creates a demarcation line that can be visualized with AS-OCT, which seems less easily distinguishable and shallower than in conventional CXL. However, its depth and visualization seems to be more similar to conventional CXL than transepithelial CXL. [ J Refract Surg . 2015;31(1):36–40.]