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Lower Laser Energy Levels Lead to Better Visual Recovery After Small-Incision Lenticule Extraction: Prospective Randomized Clinical Trial

  • Yong Woo Ji
    Affiliations
    Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea

    Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea
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  • Minseo Kim
    Affiliations
    Hankuk Academy of Foreign Studies, Yongin, South Korea
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  • David Sung Yong Kang
    Affiliations
    Eyereum Eye Clinic, Seoul, South Korea
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  • Dan Z. Reinstein
    Affiliations
    London Vision Clinic, London, United Kingdom

    Department of Ophthalmology, Columbia University Medical Center, New York, New York

    Centre Hospitalier National d'Ophtalmologie, Paris, France

    Biomedical Science Research Institute, University of Ulster, Coleraine, United Kingdom
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  • Timothy J. Archer
    Affiliations
    London Vision Clinic, London, United Kingdom

    Biomedical Science Research Institute, University of Ulster, Coleraine, United Kingdom
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  • Jin Young Choi
    Affiliations
    Eyereum Eye Clinic, Seoul, South Korea
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  • Eung Kweon Kim
    Affiliations
    Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea

    Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea
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  • Hyung Keun Lee
    Affiliations
    Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea

    Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea
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  • Kyoung Yul Seo
    Affiliations
    Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea

    Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea
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  • Tae-im Kim
    Correspondence
    Inquiries to Tae-im Kim, Department of Ophthalmology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea
    Affiliations
    Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea

    Corneal Dystrophy Research Institute, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea
    Search for articles by this author

      Purpose

      To determine the effect of lowering laser energy on clinical outcomes in small-incision lenticule extraction (SMILE).

      Design

      Prospective randomized clinical trial.

      Methods

      A total of 151 patients (151 eyes) with moderate myopia scheduled for SMILE were included: 58 eyes received SMILE with low energy (100, 105, and 110 nJ; L-SMILE group) and 93 with conventional energy (115–150 nJ; C-SMILE group). Patients received complete ophthalmic examinations preoperatively and over 3 months postoperatively.

      Results

      Uncorrected distance visual acuity (logMAR UDVA) 1 day and 1 week postoperatively was significantly better in L-SMILE than in C-SMILE (P < .001 and P = .005, respectively). There was no significant difference between the groups at 1 and 3 months. L-SMILE induced significantly fewer corneal aberrations compared with C-SMILE at 1 week and 1 month postoperatively (both P < .01), but there were no significant differences at 3 months. Though there was no difference in logMAR UDVA over the postoperative period between the 100, 105, and 110 nJ subgroups, there was a significant difference in logMAR UDVA on postoperative day 1 between L-SMILE and each subgroup in which an energy level of 115 nJ or higher was used. Furthermore, logMAR UDVA on postoperative day 1 showed a significant correlation with laser energy (r = 0.451, P < .001) and multiple linear regression analysis revealed that energy level was the only independent factor associated with logMAR UDVA on postoperative day 1 (P < .001).

      Conclusions

      SMILE using femtosecond energy of less than 115 nJ facilitates better visual acuity with less induction of corneal aberrations in the early postoperative period.
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