Abstract
Abstract: :
Purpose: To evaluate a procedure using the customized excimer laser ablation to perform a deep lamellar keratoplasty, and to assess the effects of the ablation on the donor graft and the recipient's cornea. Methods: Six patients, 5 affected from keratoconus and 1 from Groenouw dystrophy type 1, underwent an excimer laser deep lamellar keratoplasty (LaserSight Technologies Inc., Winter Park, FL). A customized ablation based on the preoperative optical pachimetry, pupil dislocation, and corneal topography (Corneal Lamellar Ablation for Transplantation®), was performed leaving a 130 microns stroma over Descemet’s membrane. The lamellar graft was prepared using the excimer laser placing the endothelium side–up. After three and nine months a confocal microscopy examination (Confoscan 3.0, Nidek Technologies) was performed in all patients. The mean follow up was 9 ± 3.8 months. Results: A slight but significant improvement in visual acuity was achieved in four patients (from 20/100–20/400 to 20/40–20/63), whereas in one subjects BCVA was unchanged. One patient underwent a penetrating keratoplasty consequently to a decrease in visual acuity due to the development of corneal aberrations after six months. In this patient the histological examination showed an epithelial ingrowth associated to a keratocyte activation. The endothelium remained unchanged, with regard to its cell count and the normal morphology, in five patients whereas an endothelial cell loss was observed in the Groenouw dystrophy. In both lamellar donor graft and recipient stroma the confocal microscopy showed activated cells in all patients. No rejection episodes were recorded. Conclusions: Our preliminary results seem encouraging. However relevant histological changes were demonstrated at the light and confocal microscope analysis. We suspect that a significant stromal dehydration and temperature increase, due to the prolonged laser exposure, leads to a keratocyte activation and consequently the tissue structural changes.
Keywords: keratoconus • microscopy: confocal/tunneling • transplantation