Study about Corneal Collagen Cross-Linking Mushroom Shape Demarcation Line Profile after Limited Bowman’s Membrane Removal by Phototherapeutic Keratectomy

We present a case of keratoconus treated with mechanical epithelial debridement (at an 8.5 mm zone) followed by limited PTK (at a 5.0 mm zone and at a 10 m depth) and CXL. AS-OCT revealed a mushroom-shaped demarcation line profile, implying that the removal of the Bowman's layer may play a role in increasing the depth of the corneal stromal demarcation line. A twenty-one-year-old male with progressive keratoconus underwent mechanical epithelial debridement (at an 8.5 mm zone) followed by PTK (at a 5.0 mm zone and in a 10 µm depth) and CXL. No intra- or early postoperative complications were found. Evaluation of the corneal stromal demarcation line depth using anterior segment optical coherence tomography revealed a mushroom shape profile. It seems that removal of the Bowman’s layer leads to greater depth of the corneal stromal demarcation line. It is possible that Bowman’s removal may induce corneal thinning through enhanced evaporation. Even though the role of Bowman’s layer in the CXL procedure is unknown this finding indicates indirectly that Bowman’s layer removal could increase the depth of CXL treatment.