Retreatment after laser in situ keratomileusis

Objective: To evaluate the effectiveness, predictability and safety of lase r in situ keratomileusis (LASIK) retreatment for correcting residual myopia . Design: Retrospective noncomparative case series. Participants and intervention: Fifty-nine consecutive eyes (43 patients) un derwent LASIK retreatment at 3 or 6 months after the primary LASIK procedur e. Lifting the corneal flap and reablating the stromal bed with a VISX 20/2 0 excimer laser was the procedure used for LASIK enhancement. Main Outcome Measures: The following parameters were studied before and aft er retreatment: visual acuity, refraction, videokeratography, applanation t onometry, and corneal thickness. Complications after LASIK enhancement also were evaluated. Follow-up was 12 months. Results: Before retreatment, only 3.38% of eyes (2 of 59) had an uncorrecte d visual acuity of 0.5 (20/40) or better, and after retreatment, this perce ntage increased to 60% (30 of 50) at 6 months and 61.8% (34 of 55) at 12 mo nths. After reoperation, mean best-corrected visual acuity improved by half a line over the values before retreatment. The preretreatment refraction o f -2.92 +/- 1.22 diopters (D) (mean +/- standard deviation) decreased signi ficantly to -0.44 +/- 0.80 D at 6 months and to -0.61 +/- 0.82 D at 12 mont hs (P < 0.001). In 82% of eyes (41 of 50) at 6 months and 81.8% (45 of 55) at 12 months, the spherical equivalent was within 1.00 D of emmetropia. The re was a significant regression of effect (0.38 D) between 3 and 12 months (P < 0.01). Postretreatment refraction was related to the original refracti on before the primary LASIK, the preretreatment refraction, and the ablatio n diameter used. Although no vision-threatening complications were found, e pithelial ingrowth and flap melting were more common after than before LASI K retreatment, with 31% of eyes at 12 months with epithelial ingrowth and 1 0.9% with flap melting. However, LASIK enhancement improved decentration an d night-vision problems. Conclusions: LASIK retreatment was an effective and predictable procedure f or correcting residual myopia. Epithelial ingrowth and flap melting were mo re frequent after than before LASIK retreatment, whereas decentration and n ight-vision symptoms improved.