Purpose: This study aimed to analyze the results of laser in situ keratomileusis (LASIK) in different degrees of myopia.
Material and methods: Three hundred consecutive eyes were divided into 4 groups according to their degree of preoperative myopia. Group I was between -3 and -6 diopters (D) (28 eyes), low myopia. Group II was between -6.25 and -10 D (138 eyes), moderate myopia. Group III was between -10.25 and -15 D (91 eyes), high myopia. Group IV was between -15.25 and -25.50 D (43 eyes), extremely high myopia. Patients were observed for 6 to 25 months.
Results: For group I, the preoperative spherical equivalent was -5.12 D +/- 0.81 standard deviation (SD), corrected visual acuity was 0.88 +/- 0.14 (SD), and keratometry was 44.09 D +/- 1.65 (SD). At the last check-up, the spherical equivalent was -0.42 D +/- 0.98 (SD), corrected visual acuity was 0.89 +/- 0.15 (SD), keratometry was 39.11 D +/- 1.61 (SD). For group II, preoperative spherical equivalent was -8.33 D +/- 1.24 (SD), corrected visual acuity was 0.72 +/- 0.22 (SD), keratometry was 44.34 D +/- 1.64 (SD). At last check-up, the spherical equivalent was -0.19 D +/- 1.22 (SD), corrected visual acuity was 0.76 +/- 0.17 (SD), keratometry was 37.56 D +/- 1.90 (SD). For group III, the preoperative spherical equivalent was -12.37 D +/- 1.49 (SD), corrected visual acuity was 0.58 +/- 0.23 (SD), and keratometry was 44.06 D +/- 1.63 (SD). At last check-up, spherical equivalent was -0.55 D +/- 1.63 (SD), corrected visual acuity was 0.61 +/- 0.18 (SD), and keratometry was 35.88 D +/- 2.18 (SD). For group IV, the preoperative spherical equivalent was -19.04 +/- 2.82 (SD), corrected visual acuity was 0.37 +/- 0.17 (SD), and keratometry was 44.02 D +/- 1.30 (SD). At last check-up, spherical equivalent was -1.49 D +/- 1.54 (SD), corrected visual acuity was 0.44 +/- 0.18 (SD), and keratometry was 33.94 D +/- 2.54 (SD).
Conclusion: With some exceptions, LASIK results generally are acceptable and stable. Nevertheless, the scatter of some cases shows that there is room for improvement, even in the most sophisticated excimer software. The high regression of group I proves the need to sample multizone software to determine whether stability is improved. Although visual results are better in patients with lower myopia, the patients whose eyes had higher ametropia more often showed improvement in their visual acuity. This may be because of the greater postoperative size of the image on the macula.