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NCT Number: NCT06477081

KLEx Versus FS-LASIK for the Treatment of Myopia and Compound Myopic Astigmatism

FemtoLASIK is a type of laser eye surgery used to correct vision problems such as nearsightedness, farsightedness, and astigmatism. It involves two main steps: creating a flap and reshaping the cornea. Refractive lenticule extraction, (KLEx) is another laser eye surgery method to correct vision issues, which involves creating and extracting a lenticule without the need of a flap. The investigators will evaluate and compare the efficacy and safety of these two procedures.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

Myopia Astigmatism Eye Diseases Myopic Astigmatism Refractive Errors

Age range

21 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Instituto de Oftalmología Conde de Valenciana

Mexico City, 06800, Mexico

About this study

Keratorefractive lenticule extraction (KLEx) is a refractive surgery technique that does not require the creation of a flap to correct the defects. The potential advantages of this technique are related to the absence of a flap, which could make it the gold standard of refractive surgery. On the other hand, femtosecond-assisted laser in-situ keratomileusis (FS-LASIK) is the most widely practiced refractive surgery worldwide, as it offers excellent visual outcomes but does require the creation of a flap to correct the defects. The objective of this study is to evaluate the effectiveness and safety of KLEx versus FS-LASIK as a treatment option in patients with myopia or compound myopic astigmatism. This is a prospective randomized study. A total of 80 participants will be randomized into two groups, the KLEx group and FS-LASIK group. Following randomization, participants will be followed on the first day after the surgery, 1 week, 1, 3, 6, and 12 months. The primary outcome is the refractive predictability at every postoperative point after surgery, which is the proportion of the number of eyes achieving a postoperative spherical equivalent within ± 0.5 diopters of the intended target. Secondary outcome parameters include quality vision measurements, refraction, visual acuity, and adverse events.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age 21 years or older
  • Corneal tomography without alterations
  • Myopia between -0.50 and -12.00 D
  • Astigmatism between -0.50 and -6.00 D

Exclusion criteria

  • Previous eye surgeries
  • Pregnancy
  • Progressive or unstable myopia and/or compound myopic astigmatism
  • Ocular surface disease

Treatment and study plan

FS-LASIK procedure

Procedure

For the FS-LASIK technique, the following steps will be followed: application of topical anesthesia to mitigate discomfort and pain throughout the procedure, and the patient will be covered with a sterile drape. Subsequently, the patient will be aligned to artificially flatten the entire corneal surface, ensuring head stability with a slight tilt to optimize surgical access and avoid nasal interference. The femtosecond laser system use will be the ATOS operating system (Schwind eye-tech-solutions, Mainparkstraße 6-10, 63801 Kleinostheim, Germany), which is responsible for creating a corneal incision to create the flap, with controlled precision to ensure proper separation of corneal layers. The excimer laser will be the Amaris (Schwind eye-tech-solutions, Mainparkstraße 6-10, 63801 Kleinostheim, Germany), responsible for performing refractive correction on the cornea through selective photoablation. Following photoablation, the flap will be carefully repositioned, and upon completion o

KLEx

Procedure

For the KLEx technique, the following steps will be followed: after topical anesthesia, a sterile drape is placed over the patient, and a speculum is inserted into the eye, centered, and aligned with a curved interface cone before applying suction. The laser used will be the ATOS operating system (Schwind eye-tech-solutions, Mainparkstraße 6-10, 63801 Kleinostheim, Germany), which performs photo-dissection starting from the posterior surface of the refractive lenticule, followed by the creation of the lenticule edge. The anterior surface of the refractive lenticule is formed by extending beyond the posterior diameter of the lenticule by 0.5 mm to form the anterior flap, followed by a peripheral cut. Specific FS laser parameters are employed for each patient. Subsequently, the suction is released, and a Siebel spatula is used to separate and reflect the flap. Finally, the refractive lenticule is extracted using toothless forceps through the small incision. Once the procedure is complete

Primary outcomes

  1. Uncorrected Visual Acuity

    Time frame: Day 1, week 1, months 1, 3, 6 & 12th after surgery.

    Visual acuity without correction after surgery.

Secondary outcomes

  1. Postoperative spherical equivalent

    Time frame: Day 1, week 1, months 1, 3, 6 & 12th after surgery.

    Overall refractive power that has both spherical and cylindrical components.

  2. Corrected Distance Visual Acuity

    Time frame: Day 1, week 1, months 1, 3, 6 & 12th after surgery.

    Visual acuity after surgery with refractive correction

  3. Loss of 2 or more lines of BCVA

    Time frame: Day 1, week 1, months 1, 3, 6 & 12th after surgery.

    Loss of 2 or more lines of best corrected visual acuity

  4. Eyes with 0.5 Diopters within refractive target.

    Time frame: Day 1, week 1, months 1, 3, 6 & 12th after surgery.

    Proportion of eye within 0.5 Diopters of refactive target.

  5. Corneal aberrations over a 5-mm pupil

    Time frame: Day 1, week 1, months 1, 3, 6 & 12th after surgery

    Corneal aberrations will be evaluated as the root mean square (RMS) values derived from Zernike polynomial coefficients. Parameters will include total higher-order aberrations (HOA-RMS), spherical aberration, and coma. Measurements will be obtained using the MS-39 anterior segment optical coherence tomography (OCT) system (CSO, Florence, Italy)

  6. Epithelial thickness

    Time frame: Day 1, week 1, months 1, 3, 6 & 12 after surgery

    Epithelial remodeling will be assessed using the MS-39 anterior segment optical coherence tomography (OCT) system (CSO, Florence, Italy). Epithelial thickness (µm) will be measured in five sectors-central, nasal, superior, inferior, and temporal.

  7. Ocular Surface Disease Index (OSDI) score

    Time frame: Week 1, months 1, 3, 6 & 12 after surgery

    The Ocular Surface Disease Index (OSDI) questionnaire, validated for the Mexican population, will be administered to assess ocular discomfort, visual symptoms, and environmental triggers associated with dry eye disease.

Other outcomes

  1. Adverse events.

    Time frame: Through study completion, an average of 1 year

    Dry eye, haze, flap complications, diffuse lamellar keratitis, corneal ectasia, epithelial ingrowth, or any other adverse event.

  2. Total surgical time

    Time frame: Intraoperative

    Surgical time will be recorded from the initiation of suction coupling on the first eye until completion of the entire procedure.

Sponsors and collaborators

Lead sponsor

Instituto de Oftalmología Fundación Conde de Valenciana

Other

Registry information

Official study title

Keratorefractive Lenticule Extraction (KLEx) Versus Femtosecond Laser-assisted in Situ Keratomileusis (FS-LASIK) for the Treatment of Myopia and Compound Myopic Astigmatism

Important dates

Study start
2024
Primary completion
2027
Study completion
2027
First posted
Jun 27, 2024
Registry last updated
Jun 25, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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