Z8 OCT-controlled 2D vs 3D LASIK

Study Overview
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Brief Summary
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The aim of this study was to test the hypothesis that OCT-guided 110 µm targeted flaps will result in accurate, predictable, and precise thickness flaps, with low complication rates when performed and compared using both 2D and 3D flap geometry applications and how it correlated to visual experience and quality of life responses during the early postoperative period.

Detailed Description
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It has been postulated that it is possible with the Ziemer Femtosecond LDV laser system to create reproducible flaps in terms of thickness and predictability. The aim of this study was to test the hypothesis that OCT-guided 110 µm targeted flaps will result in accurate, predictable, and precise thickness flaps, with low complication rates when performed and compared using both 2D and 3D flap geometry applications. Patient-reported outcomes are increasingly incorporated into clinical trials as they provide access to valuable information on the physical experience of the patient during and after the treatment. A questionnaire will therefore also be introduced in this study to evaluate how well self-reported pain, visual experience, and quality of life responses are correlated with flap geometries in both groups during the early postoperative period. The study holds direct medical benefit to the patient in this that they received an immediate improvement in his/her unaided vision. Moreover, the patient's participation contributes to the medical knowledge about the use of femtosecond lasers for refractive surgery, in particular in view of the use of intraoperative OCT visualization tools. The patients will gain access to the newest technology available for refractive surgery namely a low pulse energy high-frequency femtosecond laser.

Official Title
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Precision of 2D vs 3D Low Energy Femto-LASIK: Intraoperative and Postoperative OCT-based Study

Conditions
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Myopia, Astigmatism

Intervention / Treatment
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* Device: 2D and 3D cutting method using a low energy Femtosecond laser LDV Z8 for LASIK flap cutting


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Key inclusion criteria as described by the German Commission for Refractive Surgery (KRC) are: The recommended range of application for the correction of myopia is up to -8.00 D and for the correction of astigmatism up to 5.00 D. The limited for LASIK correction of myopia is up to -10.00 D and correction of astigmatism up to 6.00 D. If myopic astigmatism is to be corrected, the values for myopia and astigmatism must be added together. The recommended range for correction of hyperopia is up to 3.00 D. Up to 4.00 D is the range of limited application for hyperopia. Age ≥18 years with stable eyesight for over 12 months. Exclusion Criteria: Key exclusion criteria as described by the German Commission for Refractive Surgery (KRC): preoperative corneal thickness less than 480 μm predicted stromal thickness under the flap after ablation of less than 250 μm chronic progressive corneal disease and forme fruste keratoconus surgery before the age of 18 years symptomatic cataract Glaucoma with a marked loss of visual field Exudative macular degeneration. Concurrent participation in another ophthalmological clinical study Exclusion criteria irrespective of the KRC criteria: Undergone former eye surgery Contact lens wear within the two weeks prior to commencement of preoperative measurements

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 2D LASIK<br>With the 2D method, the flap resection is created in a planar mode (xy-plane), without vertical cut, at the requested depth. | Device: 2D and 3D cutting method using a low energy Femtosecond laser LDV Z8 for LASIK flap cutting<br>* 2D and 3D cutting methods were randomly used in same subjects<br>|
| Experimental: 3D LASIK<br>With the 3D method, the flap resection is done in a three-dimensional mode, at the requested depth, with the requested diameter and the desired border (side cut) angle | Device: 2D and 3D cutting method using a low energy Femtosecond laser LDV Z8 for LASIK flap cutting<br>* 2D and 3D cutting methods were randomly used in same subjects<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Predictability of central flap thickness in OCT-controlled 110 µm LASIK | Analyze central flap thickness in OCT-controlled 110 µm LASIK and to report on intended versus achieved flap thickness of one group with a 2D flap geometry in one eye and another group with a 3D flap geometry in the contralateral eye. All OCT measurements will be done in micron metres (µm). | 1 month postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of intraoperative flap thickness with pre- and postoperative results | Measurement of corneal thickness pre flap creation (Corneal Pachymetry measurements expressed in µm indicate the thickness of the cornea before flap was created. This measurement will serve as the baseline measurement. Pachymetry measured again after the flap was created and lifted by means of optical and ultrasonic pachymetry(µm) for both groups and to be compare with postoperative AS-OCT measurements also measured in µm.This will indicate how accurate the intraoperative flap thickness compare to the 1 week and 1 month thickness measurements as swelling and inflammatory processes could influence postoperative measurements. | 1 week, 1 month | 
| Postoperative planarity | Assessment of several measurements taken along the corneal cut on superior, nasal, inferior and temporal points in order to compare the uniformity of the cut between 2D vs 3D geometries. Measurments will be done by means of AS-OCT,measured in µm units.Measurements at two different follow up periods will be analyzed and compared in order to rule out the role that inflammation could possibly play. | 1 week, 1 month | 
| Intraoperative flap morphology | Observations that are defined by different scales in order to report on important features pertaining to 2D and 3D intraoperative flap geometries eg. the presence and extent of opaque bubble layer (OBL), ease of flap lifting and stromal bed quality in both groups . Intraoperative flap morphology assessment to be done as soon as the flap was created in terms of presence of an opaque bubble layer (no OBL, 30-40% of flap surface, >40% of flap surface). Once the flap was lifted to report on ease of flap lifting (easy/sticky/can not lift) and to describe the stromal bed quality (smooth,tissue bridges, rastered, lines). | During surgery | 
| Postoperative flap properties | Evaluate flap properties by means of slit lamp biomicroscopy examination. The flap's visual appearance seen with the slit lamp to be described and documented as per the suggested scales during 2 specified follow up visits in terms of edge quality and visibility ('yes/no' If yes= extreme fine line, distinct line or irregular edge), border shape (round, irregular) and interface quality (smooth, lines, cobblestones, grids, microstriae) and be compared between flap geometries (2D and 3D flaps). | 1 week, 1 month | 
| Visual outcomes | Compare pre- and postoperative visual acuity (UDVA, CDVA) measurements by means of a Snellen Visual Acuity chart and be expressed in decimal that will be converted to logMar units for the purpose of statistical analysis. | 1 day, 1 week, 1 month | 
| Patient reported Outcomes: early recovery period | Conduct a non validated Patient Reported Outcome (PRO) questionnaire adopted and based on the 'Brief Pain Inventory' questionnaire [Porela-Tiihonen] to assess patient's early visual perceptions and pain experience related to their own functional status and wellbeing and to compare between the two eyes since each undergone different cutting geometry (2D vs 3D) methods. | 1 day, 2Day, 1 week follow up | 
| Complications | Report and document any intra- and postoperative complications that may occur during the time of the procedure or at the 1 month follow up visit. | Intra- and postoperatively up to 1 month follow up | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Femtosecond Laser Assisted Laser in Situ Keratomileusis, LASIK, FEMTO LDV Z8