Demarcation line evaluation of iontophoresis-assisted transepithelial corneal collagen cross-linking for keratoconus.

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). 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. 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 µm (range: 183 to 339 µm) for the first examiner and 241.89 ± 62.52 µm (range: 163 to 358 µm) 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. 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.