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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.
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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| FemtoLASIK | Active Comparator | 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 |
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| Keratorefractive lenticule extraction | Active Comparator | 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 complet |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| 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 |
| Measure | Description | Time Frame |
|---|---|---|
| Uncorrected Visual Acuity | Visual acuity without correction after surgery. | Day 1, week 1, months 1, 3, 6 & 12th after surgery. |
| Measure | Description | Time Frame |
|---|---|---|
| Postoperative spherical equivalent | Overall refractive power that has both spherical and cylindrical components. | Day 1, week 1, months 1, 3, 6 & 12th after surgery. |
| Corrected Distance Visual Acuity |
| Measure | Description | Time Frame |
|---|---|---|
| Adverse events. | Dry eye, haze, flap complications, diffuse lamellar keratitis, corneal ectasia, epithelial ingrowth, or any other adverse event. | Through study completion, an average of 1 year |
| Total surgical time |
Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Instituto de Oftalmología Conde de Valenciana | Mexico City | Mexico City | 06800 | Mexico |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 38717080 | Background | Pradhan KR, Arba Mosquera S. SmartSight Correction of Compound Myopic Astigmatism Treatments With Preoperative Astigmatism > 1.00 Diopter Using the SCHWIND ATOS: A Retrospective Case Series. J Refract Surg. 2024 May;40(5):e328-e335. doi: 10.3928/1081597X-20240415-02. Epub 2024 May 1. | |
| 37959406 | Background |
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| ID | Term |
|---|---|
| D009216 | Myopia |
| D001251 | Astigmatism |
| ID | Term |
|---|---|
| D012030 | Refractive Errors |
| D005128 | Eye Diseases |
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Allocation sequence concealment will be done with sealed opaque envelopes. The envelope will be open prior to the intervention only to surgical team. The technique will not be known by the patient or the staff responsible of the follow-up.
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| 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 |
|
Visual acuity after surgery with refractive correction
| Day 1, week 1, months 1, 3, 6 & 12th after surgery. |
| Loss of 2 or more lines of BCVA | Loss of 2 or more lines of best corrected visual acuity | Day 1, week 1, months 1, 3, 6 & 12th after surgery. |
| Eyes with 0.5 Diopters within refractive target. | Proportion of eye within 0.5 Diopters of refactive target. | Day 1, week 1, months 1, 3, 6 & 12th after surgery. |
| Corneal aberrations over a 5-mm pupil | 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) | Day 1, week 1, months 1, 3, 6 & 12th after surgery |
| Epithelial thickness | 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. | Day 1, week 1, months 1, 3, 6 & 12 after surgery |
| Ocular Surface Disease Index (OSDI) score | 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. | Week 1, months 1, 3, 6 & 12 after surgery |
Surgical time will be recorded from the initiation of suction coupling on the first eye until completion of the entire procedure.
| Intraoperative |
| Igras E, Czarnota-Nowakowska B, O'Caoimh R. Comparison of the Clinical Effectiveness of Correcting Different Types of Astigmatism with Small Incision Lenticule Extraction. J Clin Med. 2023 Nov 6;12(21):6941. doi: 10.3390/jcm12216941. |
| 38717083 | Background | Foo VHX, Liu YC, Ang M, Htoon HM, Ting DSJ, Mehta JS. Comparative Study of Primary SMILE, SMILE Enhancement, and Femtosecond Laser-Assisted LASIK on Higher Order Aberrations and Corneal Densitometry. J Refract Surg. 2024 May;40(5):e291-e303. doi: 10.3928/1081597X-20240314-01. Epub 2024 May 1. |
| 41436254 | Derived | Muleiro-Alvarez M, Vera-Duarte GR, Medina-Estrada EA, Ortiz-Morales G, Ramirez-Miranda A, Navas A, Graue-Wiechers EL, Graue-Hernandez EO, Kahuam-Lopez N. Keratorefractive lenticule extraction (KLEx) versus femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for the treatment of myopia and compound myopic astigmatism: study protocol of a randomised clinical trial in Mexico. BMJ Open. 2025 Dec 23;15(12):e097192. doi: 10.1136/bmjopen-2024-097192. |