Visual and Refractive Outcomes of Laser In Situ Keratomileusis in Low to High Myopia: Two Years’ Follow-up

INTRODUCTION: The purpose of this study was to determine the refractive and visual acuity changes in myopic eyes after laser in situ keratomileusis (LASIK) surgery and to evaluate the stability, predictability, efficacy, and safety of the procedure.
METHODS: A total of 199 eyes of 113 patients were evaluated retrospectively at the Beyoğlu Eye Training and Research Hospital in terms of myopia and/or myopic astigmatism correction with LASIK surgery. The cases were classified as low to moderate myopia/myopic astigmatism (-0.50 to -6.00 diopters [D]) (Group 1) and high myopia (-6.25 to -16.00 D) (Group 2). Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), the rate of achieving the planned diopter value, and insufficient and excessive correction were investigated. In all cases, the laser procedure was performed with an LSX (LaserSight, Inc., FL, USA) device, and keratome incisions with a Carrazio-Barraquer or a Moria M2 microkeratome.
RESULTS: The patients were followed up for a median of 18.82±6.06 months. In the group, 52 were male (46.0%), 61 were female (53.9%), and the mean age was 30.5±8.76 years. At the last visit, the mean spherical and cylindrical refractive error in Group 1 regressed from the preoperative values of -3.31±1.54 D and -1.00±1.08 D to -0.17±0.56 D and -0.71±0.57 D, respectively. In Group 2, the mean spherical and cylindrical refractive error regressed from the preoperative values of -8.55±2.26 D and -1.64±3.36 D to -1.53±1.06 D and -0.66±0.71 D, respectively. Preoperative UCVA increased from 0.07±0.46 D to 0.83±0.75 D in Group 1 (p<0.001), and 0.03±0.58 D to 0.43±0.54 D in Group 2 (p<0.001). There was no statistically significant change in the BCVA in either group at the final visit (p>0.05 for each group). Five eyes (10%) in Group 1 and 6 eyes (18%) in Group 2 had a loss of ≥1 line on the Snellen chart with best correction. Four eyes (8%) in Group 1 and 7 eyes (21%) in Group 2 gained ≥1 line on the Snellen chart with best correction.
DISCUSSION AND CONCLUSION: LASIK surgery yielded better results in cases of low to moderate myopia, and had acceptable results in high myopia. Although refractive improvement may be achieved in high myopia, considering the low visual quality obtained and the possibility of regression, the results of high dioptric correction can be variable.