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Kerstin Wand, Karin Kobuch, Michael Baumann, May Griffith, Mohammad Islam, Johannes Junger, Raphael Neuhann, Chris Lohmann; UV-Crosslinking for Fixation of Biosynthetic Corneal Collagen Implants. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2106.
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© ARVO (1962-2015); The Authors (2016-present)
In times of donor organ shortage, also in corneal transplantation, biosynthetic corneal implants as an alternative to human donor tissue have been presented. Previously a Phase I clinical study demonstrated good results regarding stability and integration. However suture related delay in epithelial closure lead to thinning of the implant, irreversible formation of haze and irregularity of the surface in these areas. Therefore an alternative suture-free fixation method as UV-crosslinking is expected to improve the visual outcome.
We implanted different cell-free corneal implants consisting of recombinant human collagen type III: RHC III and RHC/MPC (methacrylphosphorylcholine). Ex vivo the biosynthetic corneal implants (350µm in depth, 6mm in diameter) were placed on the anterior cornea of porcine and rabbit eyes after performing deep anterior lamellar keratoplasty with either femtosecond or excimer laser. After application of Riboflavin 0.1% solution for 5 minutes UV-crosslinking was performed at either standard (3mW/cm2 for 30 minutes) or rapid procedure (18mW/cm2 for 5 minutes). Thereafter the corneas were excised, fixed in PFA4% and embedded in paraffin. Crosslinking effects (thickness and diameter of implant, adhesion between implant and cornea) were evaluated by slitlamp biomicroscopy, OCT images and finally histologically (HE-stained/ picrosirius stained sections, electronmicroscopy).
Before and after crosslinking the precise fitting of the implant could be demonstrated in OCT images. This was more accurate in porcine eyes than in rabbit eyes, maybe due to the difference in corneal thickness. Histologically we could prove crosslinks between implant and corneal stroma. After crosslinking the different types of implants showed different degrees of shrinkage. There was no difference in the outcome between standard and rapid crosslinking procedure.
UV-crosslinking as a fixation method for biosynthetic corneal implants was demonstrated to be promising. It can reduce suture-related complications as neovascularization, haze formation and surface irregularity. Biostability, integration and long term outcome is further evaluated in in vivo animal experiments.
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