Abstract
Purpose:
To assess laser assisted implantation , sutureless fixation by UV crosslinking and clinical performance of biosynthetic collagen III implants in vivo in rabbit eyes after deep anterior lamellar keratoplasty (DALK).
Methods:
Corneal implants from recombinant human collagen III (RHC III or RHC/MPC, 300µm thickness, diameter 6mm) were placed on the anterior cornea of rabbit eyes (n=12) after performing DALK with either femtosecond (Victus, Technolas PV Munich, Germany) or excimer laser (MLase Germering, Germany). Implants were prepared in a corresponding design. After application of Riboflavin 0.1% for 5 minutes UV-crosslinking was performed according to a rapid procedure (18mW/cm2 for 5 minutes). Thereafter a soft bandage contact lens was placed and a tarsoraphy was performed. Postoperatively the rabbits were observed over two or six weeks by OCT and slitlamp biomicroscopy. Finally the eyes were examined histologically (HE-stained/ picrosirius stained sections, electronmicroscopy).
Results:
Femtosecond laser assisted surgery enabled a 3D cut design for fixation of the implant. Both laser cuts showed excellent surface properties within the corneal bed and implant. Certain types of implants showed minor shrinkage after crosslinking, resulting in peripheral missmatch and reduced adhesion. Good corneal adhesion and fixation of the implant could be achieved in areas, where implant and corneal bed were in close contact intraoperatively and after crosslinking, demonstrated by OCT and histology. Loss of implant during follow up occured in 4 cases due to intra- and postoperative complications (laser n=2, opening of tarsoraphy n=2). Corneal neovascularisation was observed around the implant in 3 cases, but never within the implant. Histology showed good integration of the implant, reepithelisation and repopularisation with keratocytes.
Conclusions:
Laser assisted surgery and sutureless fixation by UV crosslinking show an excellent potential to optimize the surgical procedure and minimize complications for implantation of collagen III biosynthetic corneal implants. The procedure may be more complicated in rabbit eyes due to anatomical differences like reduced corneal thickness and different corneal curvature. The parameters for laser application will have to be further adapted to guarantee exact fitting and contact of implant and recipient cornea.
Keywords: 479 cornea: clinical science •
575 keratoprostheses