Association of fluorescein anterior corneal mosaic and corneal K-structures by in vivo laser confocal microscopy in patients with keratoconus
Authors Kobayashi A, Yokogawa H, Mori N, Masaki T, Sugiyama K
Received 16 April 2017
Accepted for publication 15 June 2017
Published 26 July 2017 Volume 2017:11 Pages 1359—1363
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Lucy Goodman
Peer reviewer comments 3
Editor who approved publication: Dr Scott Fraser
Akira Kobayashi, Hideaki Yokogawa, Natsuko Mori, Toshinori Masaki, Kazuhisa Sugiyama
Department of Ophthalmology, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan
Objective: 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]).
Methods: Sixteen keratoconic eyes in 8 consecutive patients with keratoconus (4 males, 4 females, mean age, 41.1 years) were included in this study. Slit-lamp biomicroscopic photos were taken with or without fluorescein staining. The existence of anterior corneal mosaic (ACM) after eyelid rubbing under fluorescein staining was documented. In vivo laser confocal microscopic examinations were performed for all patients in both the central cone and the peripheral cornea to examine the existence of K-structures.
Results: According to the Amsler–Krumeich scale, the eyes were graded as follows: stage 1 (n=3), stage 2 (n=1), stage 3 (n=1), and stage 4 (n=11). ACM was observed in 7 eyes (61.1%) in the cone area and 16 eyes (100%) in the peripheral cornea among all keratoconic eyes enrolled in this study. In addition, K-structures were observed in the 7 eyes (61.1%) and 16 eyes (100%) in the peripheral cornea among all keratoconic eyes. The presence of the K-structures was completely matched (100%) with the presence of ACM in both the central cone and the peripheral cornea. In 11 eyes with stage 4 keratoconus, ACM and K-structure was absent in 9 eyes (81.8%) in the cone area. On the contrary, in 5 eyes with mild-to-moderate keratoconus (grade 1 to 3), ACM and K-structure was present in all eyes (100%) in the cone area. The absent ratio of ACM and K-structures in the cone area was significantly higher in stage 4 severe keratoconus compared to mild-to-moderate keratoconus (grade 1 to 3) (Fisher, P=0.005).
Conclusion: The existence of ACM and K-structures in both the central cone and the peripheral cornea showed perfect accord in patients with keratoconus, indicating a strong association of ACM and K-structures in patients with keratoconus. With the progress of the keratoconus, it seemed that ACM and K-structure progressively disappeared, suggesting Bowman’s layer abnormalities due to keratoconus. Further study in larger groups of patients with keratoconus is required to fully understand the significance of ACM/K-structures in keratoconic eyes and their association with Bowman’s layer.
Keywords: keratoconus, anterior corneal mosaic, K-structure, confocal microscopy
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