Corneal Stromal Demarcation Line Determined With Anterior Segment Optical Coherence Tomography Following a Very High Intensity Corneal Collagen Cross-Linking Protocol

PURPOSE:To evaluate corneal stromal demarcation line depth after very high intensity (18 mW/cm) ultraviolet-A irradiation for a 5-minute corneal collagen cross-linking (CXL) protocol with the use of anterior segment optical coherence tomography. METHODS:This prospective interventional study enrolled 14 patients (18 eyes) with progressive keratoconus who underwent CXL with an ultraviolet-A irradiation intensity of 18 mW/cm for 5 minutes. One month postoperatively, corneal stromal demarcation line depth was measured with the use of anterior segment optical coherence tomography by 2 independent observers. The rate of reepithelialization and endothelial cell density at a 3-month follow-up period were also evaluated. RESULTS:No intraoperative or postoperative complications were observed in any of the patients. No statistically significant difference between the 2 observersʼ measurements was observed (P = 0.989). Mean corneal stromal demarcation line depth was 223 ± 32 μm (range, 159–265 μm). The mean endothelial cell density decreased from 2714 ± 174 preoperatively to 2671 ± 192 at 3 months postoperatively; however, this decrease was not statistically significant (P = 0.221). CONCLUSIONS:Corneal stromal demarcation line depth after a very high intensity 5-minute CXL protocol seems to be shallower than the standard Dresden protocol.