SMILE Surgery in One Eye Compared to Ray Tracing-guided LASIK Surgery in the Fellow Eye

A Prospective Randomized Comparison of SMILE Surgery to Ray Tracing-Guided LASIK Surgery

Participants will undergo LASIK surgery in one eye using ray tracing guided technology in one eye and LASIK surgery in the other eye using wavefront guided technology. We are comparing outcomes between the two technologies as measured by self reported quality of vision and quality of life outcomes using validated questionnaires before and after surgery. We will also be comparing outcomes between the two technologies including measurement of low contrast visual acuity,and best spectacle corrected visual acuity.

Study Overview

• Status: Not yet recruiting
• Conditions: Astigmatism; Myopia
• Intervention / Treatment: Device: Ray tracing guided LASIK surgery

Detailed Description

Sixty-two near-sighted study participants at Stanford are planned to undergo treatment in this clinical research trial.

This comparison will be made between both eyes of the same study participant following LASIK and SMILE surgery. One eye will have ray tracing-guided LASIK and their fellow eye treated with SMILE surgery. Both ray tracing-guided LASIK surgery and SMILE surgery have been found to be safe, predictable and effective when used for laser vision correction procedures. Both ray tracing-guided LASIK surgery and SMILE surgery used in this study have been approved for laser vision correction by the United States Food and Drug Administration. Standard refractive outcomes such as uncorrected visual acuity (vision without glasses or contact lenses) and best corrected visual acuity (vision with glasses or contact lenses), and intended vs. achieved postoperative refractions (the accuracy of the LASIK and SMILE procedures) will be evaluated.

Randomization:

The choice of which eye receives ray tracing-guided LASIK surgery and which eye receives SMILE surgery will be randomized (assigned at random) prior to enrollment. Participants will have one eye treated with ray tracing-guided LASIK and your other eye treated with the SMILE surgery. Participants will know which eye is being treated with ray tracing-guided LASIK and which eye will be treated with SMILE surgery. Both ray tracing-guided LASIK and SMILE surgery are FDA-approved procedures. Both procedures are being performed according to the FDA-approved labeling. Participants have a fifty percent chance of having their left eye treated with ray tracing-guided LASIK as their right eye (like making a choice by flipping a coin). Participants will undergo bilateral (both eyes at once) surgery.

Screening and Preoperative Assessment Participants will be partially screened via telephone. We will also ask participants to complete screening by coming to the clinic in person. This screening will include measurements of corneal thickness, the shape of the cornea using corneal topography (measures the shape of the front clear surface of the eye), a slit lamp examination of the eye (a microscope to magnify the cornea) and ocular and medical history.

Participants scheduled to undergo LASIK and SMILE surgery for the correction of myopia (nearsightedness) will be screened for eligibility. Eligible participants will be examined preoperatively to establish a baseline for ocular condition (the general health and glasses prescription of the eyes). Postoperatively, participants will undergo an ophthalmic evaluation (complete eye examination) at regular intervals as specified in this protocol. Re-treatments (a second operation on the same eye for residual nearsightedness, farsightedness and/or astigmatism) will not be allowed during the first twelve months of this study. If you elect to undergo a retreatment of your LASIK surgery prior to the 12-month post-operative visit, the data after the retreatment procedure will be excluded from the study analysis.

Participants eyes will be given a thorough examination at each visit. This examination will include the standard elements of a general eye exam including testing of the eye's vision, contrast acuity testing, examination with the slit lamp and the ophthalmoscope to look at the various parts of the eye and a test of the inner eye's pressure.

• Study Type: Interventional
• Enrollment (Estimated): 62
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Edward E Manche, MD; Phone Number: 1-650-498-7020; Email: edward.manche@stanford.edu

Study Locations

• United States
  • California
    • Palo Alto, California, United States, 94303
      • Byers Eye Institute
      • Principal Investigator: Edward E Manche, MD
      • Contact: Edward Manche E Manche, MD; Phone Number: 650-498-7020; Email: cornea@stanford.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Subjects age 22 and older with healthy eyes. Nearsightedness between -1.00 diopters and -8.00 diopters.

Subjects with less than or equal to 3.00 diopters of astigmatism.

Exclusion Criteria:

Subjects under the age of 22. Subjects with excessively thin corneas. Subjects with topographic evidence of keratoconus. Subjects with ectactic eye disorders. Subjects with autoimmune diseases. Subjects who are pregnant or nursing. Subjects must have similar levels of nearsightedness in each eye. They can not be more than 1.5 diopter of difference between eyes.

Subjects with more than 3.00 diopters of astigmatism Subjects must have similar levels of astigmatism in each eye. They can not have more than 0.75 diopters of difference between eyes.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Ray tracing guided LASIK surgery; LASIK	Device: Ray tracing guided LASIK surgery; LASIK
Active Comparator: SMILE surgery; SMILE	Device: Ray tracing guided LASIK surgery; LASIK

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in corrected distance visual acuity	The primary endpoint will be the gain in lines of corrected distance visual acuity (CDVA) at the postoperative month three follow-up compared with preoperative baseline.	Three months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in 5 and 25% low contrast CDVA	Change in 5 and 25% low contrast best corrected visual acuity from preoperative to postoperative month three	Three months
Change in patient self reported quality of vision and life	Will compare preoperative quality of vision and quality of life as measured by the validated Patient Reported Outcomes With LASIK (PROWL) questionnaire to postoperative month three.	Three months
Corneal epithelial thickness changes	Measure corneal epithelial thickness maps preoperatively and compare changes at postoperative month three	Three months
Change in higher order aberrations	Will measure preoperative higher order aberrations using wavefront aberrometry and compare to postoperative month three measurements	Three months

Collaborators and Investigators

• Sponsor: Stanford University

Study record dates

Study Major Dates

• Study Start (Estimated): August 5, 2026
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): July 31, 2029

Study Registration Dates

• First Submitted: July 18, 2026
• First Submitted That Met QC Criteria: July 18, 2026
• First Posted (Actual): July 23, 2026

Study Record Updates

• Last Update Posted (Actual): July 23, 2026
• Last Update Submitted That Met QC Criteria: July 18, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: SMILE; LASIK; Ray-tracing
• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors; Myopia; Astigmatism
• Other Study ID Numbers: 79951; 359910 (Other Grant/Funding Number: Alcon)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No