uneventful results of photo refractive keratectomy (prk) in myopic eyes with thin cornea

to evaluate long term safety and efficacy of the photo refractive keratectomy (prk) in myopic eyes with thin cornea, this study has been designed. in this retrospective case series study, we included 74 eyes of 38 myopic patients with preoperative central corneal thickness (cct) less than 550 micrometer who underwent for prk surgery prior to 2010 and had 4 years of mean follow up postoperatively. factors that were evaluated include pre and post operative refraction, uncorrected visual acuity (ucva), best corrected visual acuity (bcva), postoperative orbscan results, cct, safety and efficacy indices. thirty eight patients aged 20 to 46 years (mean age, 28.18± 6.82 years) with mean (sd) preoperative and postoperative cct of 485.92 ± 9.27 µm and 434.84 ± 2.48 µm respectively who had mean preoperative myopia and astigmatism of -2.77 d and -0.82 were evaluated. the mean postoperative myopia, astigmatism, ablation depth, preoperative bcva, postoperative bcva, postoperative ubcva safety and efficacy indices were -0.24 ± 0.39 d, -0.37 ± 0.37d, 54.34 ± 16.28 µm, 0.011 ± 0.03 logmar,  0.003 ± 0.01 logmar and 0.054 ± 0.09 logmar, 0.02 ± 0.12 and 0.11 ± 0.50 respectively. on examination for corneal clarity, 72 eyes (97.3%) had clear cornea (grade 0) and 2 eyes of one patient (2.70%) had trace haze (grade 1). on orbscan images no evidence of corneal ectasia noted in all subjects. in four years postoperative follow up of myopic patients with thin cornea (<500 µm), prk seems to have acceptable safety and efficacy which proved by stability of postoperative visual acuity, refraction and topographic outcomes as well as acceptable safety and efficacy indexes.