LASIK versus PRK for high astigmatism

Purpose: To compare the refractive outcomes of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopic astigmatism of 3 diopters (D) or more. Study design: Retrospective matched comparative study. Methods: This study include consecutive myopic patients (SE 0 to –10 D) undergoing LASIK or PRK between 2007 and 2016 with astigmatism of 3 to 6 D, and postoperative follow-up of at least 30 days for LASIK and 60 days for PRK, compared outcomes of LASIK and PRK eyes. Results: The LASIK and PRK groups comprised 175 eyes of 175 patients each, with median follow-up of 39 and 139 days, respectively (P < 0.001). Mean preoperative manifest astigmatism was –3.35 ± 0.46 and –3.42 ± 0.51 D (P = 0.92), postoperative SE was –0.43 ± 0.55 and –0.16 ± 0.64 D (P < 0.001), and arithmetic astigmatism was –0.59 ± 0.46 and –0.88 ± 0.60 D (P < 0.001), for the LASIK and PRK groups, respectively. Fifty-seven and 64.0% eyes had postoperative SE within ± 0.5 D of emmetropia (P = 0.19), and 57.7 and 38.8% eyes were within 0.5 D of attempted astigmatic correction (P < 0.001) for the LASIK and PRK groups, respectively. More PRK eyes were overtreated regarding both SE and astigmatism than LASIK eyes (P < 0.001). The efficacy and safety indices were close to 1.0 in both groups. The surgically induced astigmatism, magnitude of error, index of success, correction index and flattening index were all better in the LASIK group. Conclusion: Both LASIK and PRK achieve good outcomes in high astigmatism. LASIK achieved mild superiority over PRK.