Laser in situ Keratomileusis for Myopia of -2 to -25 Diopters

PURPOSE: To evaluate excimer laser in situ keratomileusis in the treatment of low, high, and excessively myopic eyes in Taiwan, 77 patients (104 eyes) were treated with Nidek EC-5000 excimer laser and divided into four groups. METHODS: In situ keratomileusis was performed with a Chiron or SCMD microkeratome. The Nidek EC-5000 excimer laser was used, with multiple passes and a multiple zone ablation technique was performed for myopia higher than -10.00 D. RESULTS: In eyes with a preoperative spherical power equal to or less than -7.00 D (29 eyes of 18 patients), the preoperative cycloplegic mean spherical equivalent refraction was -5.44 +/- 1.36 D. The mean postoperative subjective spherical equivalent refraction was 0.25 +/- 0.64 D at 1 month, 0.056 +/- 0.55 D at 3 months, -0.069 +/- 0.415 D at 6 months, and 0.022 +/- 0.496 D at 9 months. The predictability of postoperative 9 month results demonstrated that 86.21% of eyes were within +/-0.50 D, 96.55% were within +/-1.00 D, and 100% were within +/-2.00 D of emmetropia. In eyes with a preoperative spherical power equal to or less than -10.00 D and higher than -7.00 D, 26 eyes of 17 patients had a preoperative cycloplegic mean spherical equivalent refraction of -8.41 +/- 0.84 D. The mean postoperative subjective spherical equivalent refraction was -0.043 +/- 1.15 D at 1 month, -0.12 +/- 0.92 D at 3 months, -0.21 +/- 1.05 D at 6 months, and -0.37 +/- 1.04 D at 9 months. The predictability of postoperative 9 month results demonstrated that 76.92% of eyes were within +/-0.50 D, 80.77% were within +/-1.00 D, and 96.5% were within +/-2.00 D of emmetropia. In eyes with a preoperative spherical power equal to or less than -15.00 D and more than than -10.00 D, 40 eyes of 27 patients had a preoperative cycloplegic mean spherical equivalent refraction of -12.65 +/- 1.51 D. The mean postoperative subjective spherical equivalent refraction was 0.275 +/- 1.72 D at 1 month, -0.30 +/- 1.34 D at 3 months, -0.47 +/- 1.23 D at 6 months, and -0.62 +/- 1.23 D at 9 months. The predictability of postoperative 9 month results demonstrated that 62.5% of eyes were within +/-0.50 D, 75% were within +/-1.00 D, and 87.5% were within +/-2.00 D of emmetropia. For 19 eyes of 15 patients with a preoperative spherical power greater than -15.00 D, the preoperative cycloplegic mean spherical equivalent refraction was -19.53 +/- 2.61 D. The mean postoperative subjective spherical equivalent refraction was -0.40 +/- 1.22 D at 1 month, -0.69 +/- 1.34 D at 3 months, -0.83 +/- 1.40 D at 6 months, and -0.65 +/- 2.99 D at 9 months. The predictability of postoperative 9 month results demonstrated that 31.5% of eyes were within +/-0.50 D, 52.63% were within +/-1.00 D, and 63.16% were within +/-2.00 D. CONCLUSION: LASIK is a safe and effective technique for the treatment of low, high, and excessive myopia.