Abstract
Abstract: :
Purpose: Automated lamellar keratoplasty my means of a microkeratome has been introduced as an alternative to manual or semi–automated techniques. In this study we present the first case of automated 140 µm lamellar keratoplasty with the Carriazzo–Pendular (Schwind) microkeratome as well as in vitro results with cutting depths between 250 and 420 µm. Methods: The cornea of 1 eye of 1 patient who underwent multiple refractive surgery for myopia (10 D PRK, 2 PTK, refractive lens exchange, 1 LASIK, 1 PRK on the flap) showed persistent irregular astigmatism with insufficient residual stroma for further corrections with the excimer laser. The thinned flap was excised and a lamellar graft sutured instead. Cutting of the lamellar graft was performed by means of a modified 140 µm blade holder and succion ring for the Cariazzo–Pendular microkeratome. Additional blade holders cutting at 250, 300, 350 and 420 µm were tested at porcine eyes. Results: The lamellar transplant showed excellent healing, comparable to post LASIK surgery. All sutures could be removed within one week postoperatively. The preoperative irregular astigmatism was reduced significantly. Visual acquity remained unchanged at 10/20. No lamellar keratitis or signs of graft rejection were noted within 9 months after surgery. Analysis of the porcine lamella showed progressive variation of flap thickness with increasing cutting depths. The flap thickness varied between 25 and 75 µm. Conclusions: Automated lamellar keratoplasty at 140 µm with the Cariazzo–Pendular microkeratome seems to be an efficient way to handle complex situations after multiple refractive surgery with insufficient residual stroma. In vitro trials with porcine eye show the necessity to improve flap thickness variability at greater depths. Especially at depths beyond 350 µm safety needs further improvement before human cases can be performed.
Keywords: refractive surgery: other technologies • transplantation