LASIK for treatment of myopia and myopic astigmatism. Results of a prospective study on 100 eyes after a 1 year follow-up period

Purpose. Recently laser-in-situ-keratomileusis (LASIK) has been increasingl y used to correct refractive errors. The purpose of this investigation was to evaluate the safety, efficacy, predictability, stability and complicatio ns using the scanning spot excimer LASIK technology. Patients and methods. The results of 100 consecutive LASIK operations carri ed out between 2/1998 and 2/1999 on 60 patients (mean age 37 years, range 2 0-55 years) have been evaluated. The Hansatome (TM) microkeratome with a su perior hinge (flap diameter: 9.5 mm) and a scanning spot excimer laser (Tec hnolas C-Lasik 217) were used in all cases. The mean spherical equivalent o f the subjective manifest refraction was -6.96 +/-2.87 diopters (D), the me an sphere was -6.47 +/-2.71 D and the mean astigmatism was -0.98 +/-0.94 D. In 6% of the eyes preoperative visual acuity was not better than 20/40. Ex aminations were performed preoperatively, after 1 and 7 days, after 1,4 and 12 months. Safety, efficacy, predictability, stability and complications w ere calculated using the datagraph software (version 1.11). Results. All 100 eyes were examined after 1 day and 1 week, 96 after 1 mont h, 95 after 4 months and 92 after 1 year. Following 1 year none of the eyes lost 2 or more lines of best corrected visual acuity, 99% were within 1 li ne and 1% gained 2 lines (safety index 1.03). In 92% of all eyes an uncorre cted visual acuity of greater than or equal to0.5 was reached, in 77% great er than or equal to0.8 and in 51% greater than or equal to1.0 (efficacy ind ex 0.89). For 60 eyes (65.21%) a refractive correction of +/-0.5 D was nece ssary, for 82 eyes (89.13%) +/-1.0 D and for 91 eyes (98.91%) +/-2.0 D. The mean spherical equivalent after 1 year was -0.15 +/-1.31 D. Between 1 and 12 months a mean regression of -0.14 D occurred. On the request of the pati ents, 5 eyes were retreated during the study period for under- or over-corr ection. Complications due to the microkeratome did not occur. Corneal infec tions were not observed, a diffuse lamellar keratitis (DLK) was seen in 12 cases, but all cases healed with no loss of visual acuity. In 7 eyes a slig ht decentration of the ablation was observed using corneal topography, whic h in one case caused an increase in glare sensitivity. Conclusions. LASIK with superior hinge and scanning spot excimer photoablat ion is suitable for the correction of myopia (up to a maximum of -12 D) and for myopic astigmatism (up to a maximum of -5 D). The refractive results s howed a high stability during the 12-month study period but there is still room for improvement of the predictability.