Customizing the Amadeus II microkeratome: evaluation of cut quality with various settings using electron microscopy.

PURPOSE: To evaluate the cut quality of keratectomy specimens created with the new Amadeus II microkeratome (SIS, Ziemer Ophthalmic, Port, Switzerland) using scanning electron microscopy (SEM). Methods. Corneal cuts were performed in 24 freshly enucleated porcine eyes using the Amadeus II microkeratome with combinations of cutting-head depth, oscillation rate, head-advance speed, and reuse of the blade. For the cutting trials, a 140-microm and 160-microm cutting head with three oscillation rates of 8,000, 10,000, and 13,000 rpm and two head-advance speed rates of 1.5 and 3.5 mm/s were chosen. In each setting, the blade was reused for a second time. All eyes were included, resulting in 4 groups with 6 eyes for each configuration. The surface and edge of the corneal cut was examined using SEM. RESULTS: At fixed oscillation rates, an increase in head-advance speed led to lower quality cuts, higher surface roughness, and irregular cut edges for both cutting heads (140 microm/160 microm), especially when using the blade for a second time. At fixed head-advance speeds an increase in oscillation rates improved the cut quality for both cutting heads (140 microm/160 microm). This results in smoother surface characteristics and more regular cut edges, especially when using the blade for the first time. CONCLUSIONS: Using the Amadeus II microkeratome for laser in situ keratomileusis procedures, the optimum oscillation rate, the optimum head-advance speed, and a single use of the blade will produce a very smooth and regular surface and cut edge for safe, comfortable, and improved customized refractive surgery.

Correlation between estimated and measured corneal ablation and refractive outcomes in laser in situ keratomileusis for myopia.

PURPOSE: To evaluate the difference between the measured and the intended postoperative central corneal thickness (CCT) by optical low-coherence reflectometry (OLCR) for 3 months after myopic laser in situ keratomileusis (LASIK) and correlate it with refractive outcomes. SETTING: Center for Refractive Therapy, Department of Ophthalmology, Ludwig-Maximilians-University Munich, Germany. METHODS: The CCT was measured by OLCR before and 6 weeks and 3 months after myopic LASIK. The correlation between the difference in pachymetry and the difference in the measured and planned postoperative refraction was proven by linear regression and Pearson product moment correlation analysis (P<.05). In a subset of eyes with a 7.0 mm optical zone, the effect of the calculated ablation depth on the difference in pachymetry was evaluated. Based on the laser algorithm data, the intended ablation was 100 microm or less in Subgroup 1 and 100 microm or more in Subgroup 2. RESULTS: Forty-three eyes of 25 patients were evaluated, with 25 eyes in the subset. The difference between the measured and intended postoperative CCT was 11.1 microm +/- 8.1 (SD) at 6 weeks and 13.8 +/- 7.5 microm at 3 months. The correlation between this difference and the difference in refraction was poor (r(2) = 0.005 microm and r(2) = 0.009, respectively). With greater ablation depth (Subgroup 2), the difference in pachymetry decreased by 3 months postoperatively. CONCLUSION: The lack of correlation between differences in the measured and intended CCT and the final refraction shows the complexity of intraoperative variables in LASIK and the effect of individual wound healing.