Corneal Stromal Demarcation Line Depth Following Standard and a Modified High Intensity Corneal Cross-linking Protocol

PURPOSE: To compare the corneal stromal demarcation line depth using anterior segment optical coherence tomography (AS-OCT) after corneal cross-linking (CXL) using two different treatment protocols: the standard Dresden protocol (30 minutes with 3 mW/cm(2)) and a modified high intensity protocol (7 minutes with 18 mW/cm(2)), corresponding to a total surface dose of 5.4 and 7.5 J/cm(2), respectively. METHODS: This prospective, comparative, interventional case series included 29 keratoconic patients (32 eyes). All patients underwent CXL using the same high intensity ultraviolet-A (UV-A) irradiation device (CCL-365; Peschke Meditrade GmbH, Huenenberg, Switzerland). Sixteen eyes were treated for 30 minutes with 3 mW/cm(2) according to the standard Dresden protocol, whereas 16 eyes were treated with a novel modified high intensity CXL protocol for 7 minutes with 18 mW/cm(2) of UV-A irradiation intensity. One month postoperatively, corneal stromal demarcation line depth was measured by two independent observers using AS-OCT. RESULTS: There was no significant difference in corneal stromal demarcation line depth between observer measurements for both groups (P = .645, Dresden protocol group; P = .715, high intensity group). Mean corneal stromal demarcation line depth was 341.81 +/- 47.02 mu m for the Dresden protocol group and 313.37 +/- 48.85 mu m for the high intensity protocol group. There was no statistically significant difference (P = .104) in the corneal stromal demarcation line depth between the two groups. Mean endothelial cell density did not change significantly in either group (P = .090, Dresden protocol group; P = .103, high intensity group). No intraoperative or postoperative complications were noted. CONCLUSIONS: Corneal stromal demarcation line depth using UV-A irradiance with 3 mW/cm(2) for 30 minutes and 18 mW/cm(2) for 7 minutes was similar. It seems that the current modified accelerated CXL protocol provided the same treatment depth as the standard Dresden protocol.