visual outcomes of lasik in myopic eyes

purpose: to evaluate the visual outcomes of lasik in myopic eyes. methods: this interventional case series was performed on records of 345 eyes of 179 patients for correcting myopia with astigmatism < 3.00 diopter (d). all patients were operated by one surgeon (h.n.) with the nidek ec 5000 excimer laser. all patients had at least one year follow up. based on preoperative refraction, patients were divided into four groups: low (-1.00 to -4.00 d), moderate (-4.00 to -7.00 d), high (-7.00 to -13.00 d), and extremely high myopia (> -13.00 d). data including pre- and postoperative refraction, ucva one year after surgery, pre- and postoperative bcva, and range of emmetropia were analyzed in each group. results: mean preoperative spherical equivalent (se) was -2.84±0.73 d in low myopia group,         -5.12±0.84 d in moderate myopia group, -9.53±1.81 d in high myopia group, and -16.26± 2.23 d in extremely high myopia group. the value decreased to -0.0845±0.16 d, -0.143±0.216 d, -0.467±0.34 d, and -2.385±1.49d, respectively at one year. the percentage of eyes according to range of ametropia were as follow: 94%, 83%, 40%, and 0% of eyes were within ± 0.25 d of emmetropia; 100%, 100%, 73%, and 15% of eyes were within ±0.5 d of emmetropoia; and 100%, 100%, 95.5%, and 23% of eyes were within ±1.0 d of emmerropia in each group, respectively. postoperative ucva of 20/40 or better was achieved in 100%, 100%, 98.4%, and 30.8% of eyes and ucva of 20/20 or better was obtained in 78.9%, 73.1%, 31%, and 0% of eyes in the four groups, respectively. one year after lasik, 2.1%, 0%, 6.7%, and 0% of the eyes lost two or more lines of bcva in each group but 2.1%, 1.4%, 4.4%, and 7.7% of eyes gained more than one line of bcva. conclusion: lasik is an effective and predictable procedure for correcting myopia. the predictability of lasik decreases with increase in preoperative refractive error.