Patients who underwent SMILE at the Refractive Surgery Center of the Department of Ophthalmology, Eye and ENT Hospital of Fudan University between January, 2011 and May, 2012 were enrolled in the prospective study. Inclusion criteria included age over 18 years, sphere of -3.00 − -9.00 diopters (D) with astigmatism up to -2.00 D, corrected distance visual acuity (CDVA) of 20/20 or better, stable refraction for 2 years, and no use of any kind of contact lenses within the previous 2 weeks. Patients with systemic diseases, a history of ocular surgery or trauma, or a history of ocular disease other than myopia or astigmatism were excluded. Among these myopia patients, those who received SMILE for both eyes were recruited in the quality-of-life study. Patients over 39 years of age were excluded as requisition of the Quality of Life Impact of Refractive Correction (QIRC) questionnaire .A group of individuals who wore spectacles full-time were enrolled as a control. Inclusion criteria included age 18–39 years, CDVA of 20/20 or better, sphere of -3.00 – -9.00 D with astigmatism up to -2.00 D, stable refraction for 2 years, use of spectacles for more than 4 years, and no other ophthalmic problems.
This study followed the tenets of the Declaration of Helsinki and was approved by the ethics committee of the Eye and ENT Hospital of Fudan University. Informed written consent was obtained from all participants.
The same surgeon (XTZ) performed all the SMILE procedures. The VisuMax femtosecond laser system (Carl Zeiss Meditec, Jena, Germany) was used with a repetition rate of 500 kHz and pulse energy of 130 nJ. The lenticule diameter was set at 6.5–6.7 mm and the stromal cap was completed at a 100-μm depth with a diameter of 7.5 mm. A 90-degree single side cut with a length of 2.0–4.0 mm was created during the procedure. After surgery, topical levofloxacin, 0.1 % fluorometholone solution, and non-preserved artificial tears (carboxymethylcellulose sodium eye drops; Allergan, Inc., Irvine, CA) were used.
The outcome measures included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, and wavefront aberrations. Routine examinations, like slit-lamp examination, rotating Scheimpflug camera imaging (Pentacam, Oculus GmbH), were also preformed.
Postoperative time points included 1, 3, 6 months and 1, 2, 4 years postoperatively.
Wavefront aberrations were measured with a Hartmann–Shack WASCA aberrometer (Carl Zeiss Meditec AG) with a 6.0 mm pupil using sixth order Zernike polynomials. The root mean square (RMS) of higher-order aberrations (HOAs), spherical aberration, coma, higher-order astigmatism, trefoil and tetrafoil was calculated. Only measurements in eyes with a pupil of 6.0 mm or larger were included. Thus, the aberration measurements of thirty-seven eyes for 1, 6 months and 4 years postoperatively were collected.
The Chinese version of the QIRC questionnaire was completed by Xu Congyi et al.  and showed favorable repeatability and validity. The QIRC questionnaire was used to assess the quality of life of the spectacles group and the surgery group at the last follow-up.
All statistical analysis was performed using the Statistical Package for Social Sciences (SPSS, Version 20) (IBM, Armonk, NY, USA). The Kolmogorov–Smirnov test was used to test for normality. Non-normally distributed data were described as the mean, medium, and interquartile range (IQR). One-way analysis of variance (ANOVA) was used for the analysis of changes during the time course, with Tukey test and Scheffe test for multiple comparisons. When variables could not meet the condition of ANOVA, the Wilcoxon signed-rank test was used for paired data and the Mann-Whitney U test was used for unpaired data. For proportions, Fisher’s exact test was used. For all tests, a P < 0.05 was defined as statistically significant.