The effect of preoperative keratometry on visual outcomes after moderate myopic LASIK

PURPOSE To evaluate visual outcomes in moderately myopic eyes with flat and steep corneas (preoperatively) that have been treated with laser-assisted in situ keratomileusis (LASIK). PATIENTS AND METHODS Records of ninety-six eyes with average preoperative keratometry (K) values between 39.9 and 42.0 diopters (D) (flat) were matched with 103 eyes with preoperative K values between 46.0 and 47.2 D (steep) that underwent LASIK between March 2007 and March 2010 for moderate myopia, and were retrospectively reviewed. The primary outcome measures used to determine the effect of preoperative keratometry on visual prognosis were refraction, visual acuity, change in keratometry (ΔK), and change in spherical equivalent (ΔSE), measured at 1, 3, 6, and 12 months postoperatively. RESULTS Significant differences were found at 6 months postoperatively between the flat group and steep group in SE (P = 0.029), sphere (P = 0.018), ΔK (P = 0.002), percentage of eyes achieving SE of -0.25 to + 0.25 D (P = 0.0125), -0.26 to -0.50 D (P = 0.003), -0.51 to -1.00 D (P = 0.044), and the percentage of eyes achieving uncorrected distance visual acuity of 20/15 or better (P = 0.0006). CONCLUSION Moderately myopic eyes with flatter corneas preoperatively have better visual prognosis following LASIK compared with moderately myopic eyes with steeper corneas.