Clinical Trial: International Multicenter Study on SMILE Surgery

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: International Multicenter Study on Small Incision Lenticule Extraction(SMILE) Surgery

Brief Summary:

The purpose of this study is to carry out an international multicenter trial to get more convincing and valuable results of the SMILE surgery and compare the outcomes between the SMILE surgery and the FS-LASIK (femtosecond laser assisted-laser in situ keratomileusis) surgery.

The investigators hope to investigate the differences between the SMILE and the FS-LASIK surgery comprehensively, including the comparison of visual acuity, refraction, the correction of cylindrical diopter, the high order aberrations, the corneal biomechanics, the corneal ectasia, the characteristics of the changes of central corneal thickness and the complications. To meet the demands of a multi center trial, all the examination equipments should be same in each center, and this will limit the variations within a study


Detailed Summary:

Hypothesis: To compare the novel refractive surgery (SMILE, the intervention group) with traditional refractive surgery (FS-LASIK, the control group) in terms of visual acuity, the higher order aberrations, corneal biomechanical parameters and the complications. SMILE surgery might offer some advantages in some aspects compared with FS-LASIK surgery.

Study program

The procedures of the study are listed as follows:

All the participants accept the refractive surgery which were selected at first, and patients' routine postoperative examinations included UCVA, BCVA, slit lamp microscopy, non-contact IOP, corneal topography with the Scheimpflug tomography system, ocular higher order aberrations using the WASCA analyzer (Carl Zeiss Meditec AG), corneal biomechanical properties acquired by the Ocular Response Analyzer and/or the Corvis ST (Corvis ST, OCULUS, Wetzlar, Germany) at 1 week, 1 month, 3 months and 6 months follow-up periods after surgery.

Statistics:

Patients who have decided to choose the SMILE surgery or the FS-LASIK will be selected as participants. The propensity matching method will be used to choose proper cases for the two groups. The propensity matching method can be calculated by SPSS software. The independent variables include: the central corneal thickness (CCT), the Km (mean Pentacam keratometry), the spherical diopter (from manifest refraction), and the cylindrical diopter (from manifest refraction), the UCVA, the BCVA, the corneal resistance factor (CRF) and the corneal hysteresis (CH) (if the investigator have the Ocular Response Analyzer) of the cornea at preoperative. The closest score of eyes in the two groups will be matched.

Same as current

Current Secondary Outcome:

  • uncorrected visual acuity [ Time Frame: change from baseline with EDTRS chart at 6 months ]
  • spherical diopter [ Time Frame: change from baseline with manifest refraction at 6 months ]
  • cylindrical dioptor [ Time Frame: change from baseline with manifest refraction at 6 months ]
  • central corneal thickness [ Time Frame: change from baseline with the Pentacam system at 6 months ]
  • corneal curvature assessed by the Pentacam system [ Time Frame: change from baseline with mean Pentacam keratometry at 6 months ]
  • corneal resistance factor assessed by the Ocular Response Analyzer [ Time Frame: change from baseline at 6 months ]
  • corneal hysteresis assessed by the Ocular Response Analyzer [ Time Frame: change from baseline at 6 months ]
  • deformation amplitude assessed by the Corvis ST system [ Time Frame: change from baseline at 6 months ]
  • spherical aberration [ Time Frame: change from baseline with the WASCA system at 6 months ]
  • coma aberration [ Time Frame: change from baseline with the WASCA system at 6 months ]
  • complication [ Time Frame: intraoperative and postoperative at 6 months ]


Original Secondary Outcome: Same as current

Information By: Tianjin Eye Hospital

Dates:
Date Received: July 12, 2016
Date Started: September 2016
Date Completion: September 2017
Last Updated: December 25, 2016
Last Verified: July 2016