Microwave thermal keratoplasty for myopia: Keratoscopic evaluation in porcine eyes

PURPOSE: Microwave thermal keratoplasty applies microwave energy to elevate the temperature of the paracentral stroma of the cornea to its thermal shr inkage temperature of about 60 degreesC. A suitable pattern of shrinkage in the paracentral cornea can flatten the central cornea. A surface cooling s ystem preserves the epithelium during the procedure. METHODS: Fourteen enucleated porcine eyes were treated with a prototype mic rowave thermal keratoplasty applicator that heated in a ring pattern with i nner diameter of 3.2 mm and width of 0.7 mm. The change in corneal power wa s quantified by a videokeratoscope. Slit-lamp microscope examinations and h istological assessments were made. RESULTS: The 3-mm simulated keratometry reading showed an average of 6.60 /- 6.00 D (standard deviation) of flattening. The region of opacity associa ted with shrinkage extended to 62% (+/- 26%) of the corneal thickness. The epithelium was intact in all eyes. CONCLUSIONS: Microwave thermal keratoplasty applied in the paracentral corn ea may flatten the central cornea.