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

Yong Woo Ji, Minseo Kim, David Sung Yong Kang, Dan Z. Reinstein, Timothy J. Archer, Jin Young Choi, Eung Kweon Kim, Hyung Keun Lee, Kyoung Yul Seo, Tae im Kim

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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.

Original languageEnglish
Pages (from-to)159-170
Number of pages12
JournalAmerican Journal of Ophthalmology
Publication statusPublished - 2017 Jul


All Science Journal Classification (ASJC) codes

  • Ophthalmology

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