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Riboflavin–UV-A Crosslinking for Fixation of Biosynthetic Corneal Collagen Implants

Wand, Kerstin MD; Neuhann, Raphael; Ullmann, Andrea; Plank, Katharina; Baumann, Michael; Ritter, Roland; Griffith, May Prof; Lohmann, Chris P. MD; Kobuch, Karin MD

doi: 10.1097/ICO.0000000000000399
Basic Investigation

Purpose: To evaluate riboflavin–UV-A crosslinking as an alternative suture-free fixation method for biosynthetic corneal collagen implants.

Methods: A range of cell-free corneal implants consisting of recombinant human collagen type III were examined. In vitro, the implants were crosslinked with different riboflavin solutions and irradiations. Ex vivo, the biosynthetic corneal implants were placed on the anterior cornea of porcine and rabbit eyes after performing deep anterior lamellar keratoplasty with a trephine, femtosecond laser, or excimer laser. UV-A crosslinking was performed with isotonic or hypotonic riboflavin at either standard or rapid procedure. The corneas were excised, fixed in PFA 4%, and embedded in paraffin. Crosslinking effects on the implants and the adhesion between implant and corneal bed were evaluated by slit-lamp biomicroscopy, optical coherence tomography (OCT) images, and histologically.

Results: After the crosslinking procedure, the implants showed different degrees of thinning. The accuracy of cutting the corneal bed was highest with the excimer laser. Good adhesion of the implant in the corneal bed could be demonstrated in OCT images. This was more accurate in porcine eyes than in rabbit eyes. Histologically, crosslinks between implant and corneal stroma were demonstrated. There was no difference between standard and rapid crosslinking procedures.

Conclusions: Riboflavin–UV-A crosslinking as a fixation method for biosynthetic corneal collagen implants was demonstrated to be promising. It can reduce suture-related complications such as haze formation and surface irregularity. Stability of the implants, especially shrinkage after riboflavin–UV-A crosslinking, needs to be further evaluated. Biostability, integration, and long-term outcome are further evaluated in in vivo animal experiments.

*Department of Ophthalmology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany;

MLase AG, Germering München, Munich, Germany;

Technolas PV Bausch & Lomb, Munich, Germany; and

§Department of Clinical and Experimental Medicine and Integrative Regenerative Medicine Centre, Linköping University, Linköping, Sweden.

Reprints: Kerstin Wand, MD, Department of Ophthalmology, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, D-81675 München, Germany (e-mail:

Supported by EU nanomedicine ERA-net project I-CARE, with funding from VDI (Verein Deutscher Ingenieure) and VDO to MLase AG, Swedish Research Council to MG.

M. Baumann works for MLase AG; R. Ritter works for Technolas PV Bausch & Lomb. The remaining authors have no conflicts of interest to disclose.

Received October 17, 2014

Received in revised form January 04, 2015

Accepted January 19, 2015

Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.