Low-energy SMILE

Reducing the laser energy settings for small-incision lenticule extraction (SMILE®) procedures results in dramatically improved visual acuity outcomes in the immediate postoperative period, according to a study presented at the 37th ESCRS Congress 
in Paris. “Reduced energy settings, with lower energy per spot and wider spot spacing, only recently became available in the United States. After applying these changes, we noticed a dramatic improvement in uncorrected visual acuity on postoperative day one, with patients reliably achieving 20/20 or better,” said Jillian Chong MD. Although SMILE treatments for myopia and myopic astigmatism have been FDA-approved since February 2017 and October 2018 respectively, American surgeons have been slow to embrace lenticule extraction as their first-choice refractive procedure, noted Dr Chong. “Despite knowledge that there is a decreased incidence of dry eye and an improvement in biomechanical stability in patients treated with SMILE compared to LASIK, surgeons have been reluctant to switch – partly due to the excellent postoperative day-one visual acuities and overall efficacy of LASIK. There is also a perception that patients treated with SMILE take longer to recover postoperatively,” she said. Dr Chong noted that the initial FDA approval for myopia was for a laser spot spacing of 3.0μm, which was subsequently extended to a range of 3.0-to-4.5μm for myopic astigmatism. The spot spacing is relevant in SMILE procedures, as there is an increased risk of opaque bubble layer (OBL) formation with higher energy settings. The presence of OBL can interfere with laser penetration and result in more complex and traumatic dissections, which in turn prolong recovery time, she said. “Our hypothesis was that the wider spot spacing and lower energy settings would improve the speed of postoperative recovery for patients treated with SMILE,” she said. Dr Chong’s retrospective study included 262 eyes treated by a single surgeon (D. Rex Hamilton, Santa Monica Eye Medical Group, Los Angeles, CA, USA) over a 12-month period. Patients were divided into three categories: low-energy SMILE (24), high-energy SMILE (129) and LASIK (175), with endpoints being uncorrected visual acuity one day and one month after surgery. For SMILE outcomes, the difference in uncorrected visual acuity (UCVA) at day one postoperatively was highly statistically significant in favour of the low-energy group. The low-energy group also closely matched the performance of LASIK, with 89% attaining UCVA of 20/20 or better compared to 91% for LASIK and just 24% for high-energy SMILE. At one month after surgery, 100% of low-energy SMILE eyes had UCVA of 20/20 or better compared to 95% for LASIK and 74% for high-energy SMILE. “This improvement may render SMILE more attractive to patients and to refractive surgeons in the United States and increase the adoption rate of this procedure,” said Dr Chong. Jillian Chong: 
Jillian.Chong@nyulangone.org

Tags: SMILE