A Small Incision Lenticule Extraction Procedure for the Correction of Myopia after One Year

Abstract

Objective: To evaluate the clinical effect after a femtosecond laser corneal small incision lenticule extraction (SMILE) procedure for the correction of low, moderate, and high myopia. Methods: This was a retrospective case series study. 86 patients (141 eyes) with myopia were chosen to undergo the SMILE procedure between December 2014 and September 2015 at the Department of Ophthalmology, Wuhan General Hospital of the Chinese PLA, all patients completed 1 year of follow-up. The average age of the patients was 23.9±5.2 years (range 18 to 35 years). According to the preoperative spherical equivalent (SE), treated eyes were divided into three groups: a low myopia group (-0.50 D<SE≤-3.00 D) with 35 eyes, a moderate myopia group (-3.00 D<SE≤-6.00 D) with 54 eyes, and a high myopia group (-6.00 D<SE≤-10.00 D) with 52 eyes. Preoperative SE was -2.12±0.63 D, -4.71±0.88 D, and -7.24±0.76 D in the three groups, respectively. Follow-up visits were at 1 day, 1 week and 1, 3, 6, 12 months after surgery. The outcome measures included uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) and postoperative SE. The results were analyzed with repeated measures analysis of variance and single factor analysis. Results: UCVA gradually increased with time after surgery in all three groups (P<0.001). At one year postoperatively, 35 eyes (100%), 54 eyes (100%) and 50 eyes (96%) had a UCVA of 5.0 or greater in the three respective groups. The efficacy indexes were 1.00±0.01, 1.00±0.01, 0.99±0.02 for the three groups. BCVA gradually increased after SMILE in the low and moderate myopia groups (F=4.73, P<0.001; F=19.53, P<0.001), but there was no significant difference in the high myopia group (F=1.87, P=0.12). No eyes lost two or more lines. Thirty-four eyes achieved a stable or improved BCVA postoperatively included 34(97%), 51(94%), 47(90%) in the low, moderate and high myopia groups, respectively. The safety indexes were 1.01±0.01, 1.01±0.01, 1.00±0.01 for the three groups. The postoperative SE in the low myopia group remained stable, while in the moderate myopia group, it was overcorrected in the early stages after surgery and gradually reached emmetropia at one year. In the high myopia group, there was a little regression at one year. Conclusions: All patients achieved good vision after SMILE, and SMILE is a safe and effective procedure for the correction of low, moderate, and high myopia, and has excellent predictability and stability, especially for low and moderate myopia. Key words: small incision lenticule extraction; myopia; clinical effect