Outcome of PRK in Management of Post LISIK Residual Myopia and Myopic Astigmatism

Abstract

Background: Different retreatment options are available for management of post LASIK residual myopia and myopic astigmatism, however PRK reduces the risk of ectasia by preserving the corneal stroma as much as possible and avoids the flap-related complications. Purpose: To evaluate the outcome as regards the safety, efficacy, and predictability of photorefractive keratectomy (PRK) for correction of residual myopia and myopic astigmatism after laser in situ keratomileusis (LASIK). Patients and Methods: The study included 30 eyes of 15 patients retreated by PRK for residual myopia and myopic astigmatism after laser in situ keratomileusis (LASIK).Data included uncorrected and best corrected visual acuity (UCVA and BCVA), spherical equivalent (SE), central pachymetry, corneal higher order aberrations (HOAs), corneal hysteresis (CH), corneal resistance factor (CRF), and corneal haze. Results: This study was performed on 30 eyes of 15patients. The mean age was 25.27±3.70 SD years old (9 women and 6 men). The average interval between procedures was 13.35 ± 5.51 months. The mean follow-up was 16.58 ± 3.06 months. Before PRK, the mean UCVA and BCVA were 0.35 ± 0.18 and 0.91 ± 0.07, respectively. The mean central pachymetry was 400.21 ± 7.8 μm, the mean SE was −1.74 ± 0.51 D. 12 months postoperatively. The mean UCVA and BCVA were 0.78 ± 0.14 (P = 0.01) and 0.92 ± 0.13 (P > 0.5), respectively. The mean central corneal thickness was 382.41 ± 2.61 μm, the mean SE was −0.18 ± 0.32 D (P < 0.01). Two eyes gained 1 line of best spectacle-corrected visual acuity; one eye lost 1 line because of corneal ectasia. No other sight-threatening complications was occurred postoperatively. Conclusions: Photorefractive keratectomy and mitomycin C was an effective, predictable, and safe procedure for correcting residual myopia and myopic astigmatism less than 3 D after LASIK. This decrease postoperative ectasia and avoids the flap related complications but has no significant effect on HOAs.