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Epi-LASIK versus LASEK and PRK

de Benito-Llopis, Laura MD, PhD; Teus, Miguel A. MD, PhD

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Journal of Cataract & Refractive Surgery: April 2012 - Volume 38 - Issue 4 - p 732
doi: 10.1016/j.jcrs.2012.01.021
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We would like to make a point about the appropriate nomenclature of techniques in the article by Taneri et al.1 Epi-LASIK is the abbreviation of “epipolis laser in situ keratomileusis” not “epithelial laser in situ keratomileusis.”2 It means superficial LASIK, since the Greek word “epipolis” means “superficial.” We believe careful nomenclature usage is essential to avoid confusion between techniques. For example, reference 4 in the paper,3 which uses the misnomer epi-LASEK in the title, is in fact a study about the usual laser-assisted subepithelial keratectomy (LASEK) technique, not about epi-LASIK as the authors suggest.

We would also like to highlight some points of the study's statistical approach that may have affected the results. The number of eyes included in each group was 20, and therefore a nonparametric test should have been used for statistical analysis.

More important, eyes in which deep ablations were performed received mitomycin-C (MMC), which is a potent antihaze drug. Therefore, the effect of any other intervention, such as repositioning the epithelial flap, might have been too small compared with the effect of the MMC. Since the incidence of haze is low with low ablations and since the authors use MMC for high-risk cases only, the risk for haze (and the risk for worse visual and refractive visual results) in this specific study was probably too low to allow detection of differences between such small groups. The authors should have analyzed the statistical power of their study; the fact that they did not find any differences does not rule out the possibility that they might have found them had they increased the number of cases included. Previous studies suggest some differences between epi-LASIK and LASEK4/PRK5 favoring the latter techniques.


1. Taneri S, Oehler S, Koch J, Azar D. Effect of repositioning or discarding the epithelial flap in laser-assisted subepithelial keratectomy and epithelial laser in situ keratomileusis. J Cataract Refract Surg. 2011;37:1832-1846.
2. Katsanevaki VJ, Kalyvianaki MI, Kavroulaki DS, Pallikaris IG. Epipolis laser in-situ keratomileusis: an evolving surface ablation procedure for refractive corrections. Curr Opin Ophthalmol. 2006;17:389-393.
3. Anderson NJ, Beran RF, Schneider TL. Epi-LASEK for the correction of myopia and myopic astigmatism. J Cataract Refract Surg. 2002;28:1343-1347.
4. Teus MA, de Benito-Llopis L, García-González M. Comparison of visual results between laser-assisted subepithelial keratectomy and epipolis laser in situ keratomileusis to correct myopia and myopic astigmatism. Am J Ophthalmol. 2008;146:357-362.
5. O'Doherty M, Kirwan C, O'Keeffe M, O'Doherty J. Postoperative pain following epi-LASIK, LASEK and PRK for myopia. J Refract Surg. 2007;23:133-138.
© 2012 by Lippincott Williams & Wilkins, Inc.