Comparison of femtosecond laser small-incision lenticule extraction and laser-assisted subepithelial keratectomy to correct myopic astigmatism

J Cataract Refract Surg. 2015 Nov;41(11):2476-86. doi: 10.1016/j.jcrs.2015.05.043.

Abstract

Purpose: To compare the efficacy of correcting myopic astigmatism with femtosecond laser small-incision lenticule extraction (SMILE, Carl Zeiss Meditec AG) versus laser-assisted subepithelial keratectomy (LASEK).

Setting: The study was conducted at the Ophthalmology Department, Eye and ENT Hospital, Shanghai, China.

Design: A retrospective, cross-sectional study.

Methods: This study included patients who underwent small-incision lenticule extraction or LASEK for the correction of myopia and myopic astigmatism. Preoperative and 6-month postoperative astigmatism values were analyzed. The efficacies of the 2 surgeries to correct astigmatism were compared.

Results: A total of 180 right eyes of 180 patients (small-incision lenticule extraction: n = 113, LASEK: n = 67) were included. No significant difference was found between the 2 groups in the preoperative astigmatism (small-incision lenticule extraction: 1.16 ± 0.85D, LASEK: 1.16 ± 0.83D, P > .05) or the postoperative astigmatism (small-incision lenticule extraction: 0.35 ± 0.37D; LASEK: 0.31 ± 0.42D, P > .05), determined by manifest refraction. No significant difference was found between the 2 groups in surgically induced astigmatism vector (small-incision lenticule extraction: 1.13 ± 0.83D, LASEK: 1.01 ± 0.65D, P > .05). The correction index was higher for the small-incision lenticule extraction group (1.05 ± 0.53) than for the LASEK group (0.95 ± 0.21, P = .045). The postoperative astigmatism was significantly higher for the small-incision lenticule extraction group when the preoperative astigmatism was 1.0 D or less (small-incision lenticule extraction: 0.26 ± 0.30D, LASEK: 0.12 ± 0.20D, P = .007) and lower for the small-incision lenticule extraction group when the preoperative astigmatism was more than 2.0 D (small-incision lenticule extraction: 0.48 ± 0.37D, LASEK: 0.89 ± 0.46D, P = .002).

Conclusions: An adjustment of nomograms for correcting low astigmatism (≤1.0 D) by small-incision lenticule extraction is suggested due to the tendency toward overcorrection, whereas a nomogram adjustment for tissue-saving ablation profile is needed for the correction of high astigmatism (>2.0 D) by LASEK due to the tendency toward undercorrection.

Financial disclosure: The authors declare that they have no competing financial interests.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Astigmatism / physiopathology
  • Astigmatism / surgery*
  • Corneal Stroma / surgery*
  • Corneal Topography
  • Cross-Sectional Studies
  • Female
  • Humans
  • Keratectomy, Subepithelial, Laser-Assisted / methods*
  • Lasers, Excimer / therapeutic use*
  • Male
  • Microsurgery / methods
  • Middle Aged
  • Myopia / physiopathology
  • Myopia / surgery*
  • Nomograms
  • Postoperative Period
  • Preoperative Period
  • Refraction, Ocular / physiology
  • Retrospective Studies
  • Visual Acuity / physiology
  • Young Adult