Kobayashi A, et al. – This study is performed to report the in vivo laser confocal microscopy findings of corneas with keratoconus, with special attention to abnormality of Bowman's layer and sub–Bowman's fibrous structures (Kobayashi–structures [K–structures]). The existence of anterior corneal mosaic (ACM) and K–structures in both the central cone and the peripheral cornea showed perfect accord in patients with keratoconus, showing a strong relationship of ACM and K–structures in patients with keratoconus. With the progress of the keratoconus, it appeared that ACM and K–structure progressively disappeared, recommending Bowman's layer abnormalities because of keratoconus. Further study in larger groups of patients with keratoconus is required to fully understand the importance of ACM/K–structures in keratoconic eyes and their relationship with Bowman's layer.