Laser in situ keratomileusis (LASIK) for myopia from -7 to -18 diopters.

Abstract

Laser in situ keratomileusis (LASIK) combines a lamellar corneal flap with an excimer laser ablation in the stromal bed to correct a wide range of myopia. We reviewed 43 eyes treated with LASIK to correct -7.00 to -18.50 diopters (D). The data from 43 consecutive eyes of 30 patients aged 24 to 46 years were analyzed. Surgery was performed under topical anesthesia using the Chiron Automated Corneal Shaper and Keracor 116 Excimer laser with the multizone mode and our modified nomogram. Manifest and cycloplegic refraction, uncorrected visual acuity, spectacle corrected visual acuity, videokeratography, endothelial cell count, slit-lamp microscopy, fundus examination, and applanation tonometry were recorded preoperatively and at 1 week and 1, 3, and 6 months, postoperatively. We divided the eyes into two groups. The lower myopia group had a mean preoperative spherical equivalent refraction of -9.30 +/- 1.31 D (range: -7.00 D to -12.00 D) and mean postoperative refraction of -0.80 +/- 0.79 (range: -0.25 D to -3.50 D). The mean spectacle corrected visual acuity preoperatively was 0.74 +/- 0.20 and postoperatively was 0.74 +/- 0.18. The higher myopia group had a mean preoperative spherical equivalent refraction of -14.86 +/- 1.87 D (range: -12.25 D to -18.50 D) and a mean postoperative refraction of -1.80 +/- 1.29 D (range -1.00 D to -5.25 D). The mean spectacle corrected visual acuity preoperatively was 0.50 +/- 0.19 and postoperatively was 0.51 +/- 0.18. No overcorrections occurred in either group. One eye of the higher group lost one line of spectacle corrected visual acuity. No eye had visually significant corneal haze. The mean change in spherical equivalent refraction between preoperatively and 6 months postoperatively was 8.50 D for the lower myopia group and 13.06 D for the higher myopia group, in the myopic direction. Visual rehabilitation was rapid after surgery. In this study, LASIK resulted in insignificant corneal scarring, stable refractive correction over six months, no irregular astigmatism, and excellent visual acuity. Predictability was more accurate up to -12.00 D of intended correction.