Endothelial cell morphology after phototherapeutic keratectomy

The purpose of the present study was to investigate endothelial vital reactions after the performance of large central excimer laser keratectomies at various depths. Central 5 mm keratectomies were performed in porcine eyes. The ablations were carried out at depths of 0 (controls), 200, and 400 micron or until perforation occurred. One-third of the corneas were immediately stained with trypan blue and alizarin red, and two-thirds of the eyes were perfused for 1 or 6 h prior to vital staining. The numbers of endothelial cells and damaged cells were assessed. No significant difference was found between 200- and 400 microns deep keratectomies as compared with control corneas at any given time. Perforated corneas showed endothelial and stromal cell damage surrounding the perforation. We conclude that deep excimer laser keratectomies do not affect endothelial cell density and viability for up to 6 h postoperatively. Therefore, excimer laser lamellar keratoplasties appear to be a safe procedure for the underlying endothelium.