Comparison of clinical outcomes after femtosecond laser in situ keratomileusis in eyes with low or high myopia

Abstract

AIM: To compare the clinical results of femtosecond (FS) laser in situ keratomileusis (LASIK) in high myopic patients and low myopic patients. METHODS: This study included 212 myopic eyes undergoing LASIK using a VisuMax 500kHz FS laser. All treated eyes were assigned to one of two groups according to preoperative manifest spherical refraction: low myopia group (A, >-4.0 D) and high myopia group (B, <=-4.0 D). Uncorrected and corrected distance visual acuity (UDVA, CDVA), refractive errors, and higher-order aberrations (HOAs) were measured preoperatively and 1wk, 1, 3 and 6mo postoperatively. RESULTS: At 6mo of follow-up, 92% and 76% had a UDVA of 20/20 or better in group A and B, respectively (P=0.037) and UDVA was significantly different between two groups (P=0.042). Six and seven percentage lost one line of CDVA in group A and B, respectively (P=0.572) and no eyes in both groups lost more than two lines. Each group had 87% and 76% of treated eyes within +/- 0.5 D of the intended correction (P=0.186), and 13% and 43% with a change of >0.50 D in spherical equivalent from 1wk to 6mo postoperatively (P=0.005). In terms of postoperative astigmatism, each group had 89.1% and 76.6% within +/- 0.50 D, respectively and there was significant difference (P=0.006). Group A tends to induce smaller HOAs than group B. CONCLUSION: FS LASIK is effective and safe for correcting high myopia as well as low myopia. However, high myopic eyes showed more postoperative astigmatism and HOAs which affect visual acuity.