Enhancement after Small-Incision Lenticule Extraction: Incidence, Risk Factors, and Outcomes.
To report the incidence, risk factors, and outcomes of enhancement after small-incision lenticule extraction (SMILE).



Retrospective cohort study.



Five hundred twenty-four eyes of 307 patients who underwent SMILE at Singapore National Eye Center between February 2012 and March 2016.



The data collected included patient age at primary SMILE, gender, race, preoperative and postoperative manifest refraction spherical equivalent (MRSE), preoperative and postoperative uncorrected distance visual acuity and corrected distance visual acuity, the occurrence of suction loss during the procedure, and the need for enhancement. All enhancements were carried out by performing an alcohol-assisted photorefractive keratectomy (PRK) procedure with application of mitomycin C (MMC).



Incidence, prevalence, preoperative and intraoperative risk factors for enhancement, and outcomes after enhancement.



The prevalence of enhancement was 2.7%, and 71.4% eyes had enhancement within 1 year of primary SMILE. The incidence of enhancement was 2.1% and 2.9% at 1 and 2 years, respectively. Age older than 35 years, preoperative MRSE more than -6.00 diopters (D), preoperative myopia more than 6.00 D, preoperative astigmatism more than 3.00 D, and intraoperative suction loss were significant risk factors for enhancement after SMILE after adjusting for all other covariates (odds ratios, 5.58, 4.80, 1.41, 3.06, and 2.14, respectively; P = 0.004, 0.021, 0.022, 0.002, and 0.020, respectively). In the patients who underwent bilateral SMILE, the first-operated eye had a marginal trend toward significance for enhancement (P = 0.054). There was no gender or racial difference. In the 14 eyes requiring enhancement, the uncorrected distance visual acuity before enhancement ranged from 20/80 to 20/25, and the mean attempted enhancement spherical equivalent was -0.50±0.86 D. The uncorrected distance visual acuity improved in most patients (92.9%) after enhancement.



The 2-year incidence of enhancement after SMILE was 2.9%. Risk factors associated with enhancement included older age at SMILE procedure, greater preoperative MRSE, greater preoperative myopia, greater preoperative astigmatism, and the occurrence of intraoperative suction loss. Clinical outcomes of using PRK with application of MMC for enhancement were good.
Singapore Eye Research Institute, Singapore, Republic of Singapore; Singapore National Eye Center, Singapore, Republic of Singapore.
Yu-Chi
YC
Liu
Singapore Eye Research Institute, Singapore, Republic of Singapore; Singapore National Eye Center, Singapore, Republic of Singapore.
Mohamad
M
Rosman
Singapore Eye Research Institute, Singapore, Republic of Singapore; Singapore National Eye Center, Singapore, Republic of Singapore; Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore, Republic of Singapore; School of Material Science & Engineering and School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, Republic of Singapore. Electronic address: jodmehta@gmail.com.
Jodhbir S
JS
Mehta
D000328:Adult; D000477:Alkylating Agents / Q000008:administration & dosage; D015331:Cohort Studies; D003319:Corneal Stroma / Q000601:surgery*; D048988:Corneal Surgery, Laser / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D016685:Mitomycin / Q000008:administration & dosage; D009216:Myopia / Q000453:epidemiology* / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000706:statistics & numerical data*; D012029:Refraction, Ocular / Q000502:physiology; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology
D000477:Alkylating Agents; D016685:Mitomycin