Abstract
Abstract: :
Purpose: Corneal refractive surgery with LASEK is an established method to treat mild to moderate myopia. One of the postoperative complications ist he development of superficial corneal scarring. Intraoperative application of Mitomycin C (MMC) has been shown to reduce the amount of corneal scarring after LASEK. Methods: 50 patients with an average follow–time of 6 months were retrospectively evaluated for quality of vision including photopic and mesopic snellen visual acuity, contrast sensitivity and higher order aberration. The endothelial cell cound was also documented. Eyes with an ablation depth of 70 µm or more than 70 µm received 0.01% or 0.02% MMC for 60 seconds respectively. In–vitro experiments with hole human eyes not suitable for corneal transplantation including excimer laser sblation of 150 µm, MMC (0.01% or 0.02%) application was also performed (30 seconds, 60 seconds, 120 seconds application time) to evaluate MMC toxiticy. The corneas were afterward stored at 4° for 18 hours and then in corneal culture medium for another 3 days. Routine histology and immunohistochemical staining for caspase 3 was then performed. Results: None of the eyes developed corneal scarring postoperatively during the follow up period. No postoperative complications were observed. There was significant difference in the endothelial cell count before and after MMC application. In–vitro experiments showed loss of corneal keratocytes in the application area at a concentration of MMC 0.02%. At an application time of 2 minutes the cell loss was observed down to descemets membrane, and at an application time of 1 minute, only the superficial 20% of corneal thickness were involved with keratocyte loss. MMC 0.01% did not show any keratocyte cell loss at any application time. The endothelial cells did not show any changes after MMC application. Conclusions: MMC is a useful drug to inhibit post LASEK haze formation, but should be used carefully, even if clinical complications were not observed. MMC induces keratocyte cell death, especially at a concentration of 0.02% for 2 minutes.
Keywords: cornea: stroma and keratocytes • myopia • refractive surgery: PRK