Evaluation of the Change in the DA Ratio, IR and SSI as Parameters of Corneal Biomechanics Post Different LVC Procedures

Study Overview
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Brief Summary
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In the study, The Investigators will compare the participates' corneal biomechanical properties including: Deformation Amplitude ratio (Da Ratio) Integrated Radius (IR) Stress strain index (SSI) All measurements will be taken before and after 3 months of LVC.

Detailed Description
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Each Participant will undergo preoperative pentacam and corvis scan for his eyes and the 3 months post operative. The participants are divided into 3 groups, one who underwent LASIK, one PRK and one Femto LASIK. Collected data will before and after surgery will be compared in each arm and then the 3 arms will be compared together.

Official Title
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Evaluation of the Change in the Deformation Amplitude Ratio, Integrated Radius and Stress Strain Index as Parameters of Corneal Biomechanics Post Different Laser Vision Correction Procedures

Conditions
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Corneal Biomechanics

Intervention / Treatment
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* Diagnostic Test: CORVIS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: • Age range 18 - 40 years. Normal eyes with normal tomographic indices. Patients with maximum mean refractive spherical equivalent (MRSE) of -7.00 diopters and with maximum astigmatism of -3.00 diopters. Exclusion Criteria: • Patients with any other coexisting corneal diseases. Keratoconus eyes. Eyes with previous refractive corneal surgery. Patients with increased intraocular pressure.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 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: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Laser In situ Keratomileusis (LASIK)<br>Measurement of the deformation amplitude ratio, integrated radius and stress strain index as corneal biomechanical indices in refractive patients before and after LASIK | Diagnostic Test: CORVIS<br>* Measurement of the DA ratio, IR and SSI before and after for patients under gone LASIK, femto LASIK and PRK using the CORVIS device.<br>|
| Active Comparator: Femto-second assisted LASIK (FS-LASIK)<br>Measurement of the deformation amplitude ratio, integrated radius and stress strain index as corneal biomechanical indices in refractive patients before and after Femto LASIK | Diagnostic Test: CORVIS<br>* Measurement of the DA ratio, IR and SSI before and after for patients under gone LASIK, femto LASIK and PRK using the CORVIS device.<br>|
| Active Comparator: Photorefractive Keratectomy (PRK)<br>Measurement of the deformation amplitude ratio, integrated radius and stress strain index as corneal biomechanical indices in refractive patients before and after PRK | Diagnostic Test: CORVIS<br>* Measurement of the DA ratio, IR and SSI before and after for patients under gone LASIK, femto LASIK and PRK using the CORVIS device.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluation of the changes in DA ratio, integrated radius and SSI before and after LVC | Comparison between in DA ratio (DA ratio) in patients undergoing LASIK, Femto LASIK and PRK. Comparison between changes in integrated Radius (IR) in patients undergoing LASIK, Femto LASIK and PRK. Comparison between changes in Stress strain index (SSI) in patients undergoing LASIK, Femto LASIK and PRK. Each indices will be compared before and after the Laser vision correction (LVC) procedure and the indices are not to be compared to each other to have have a fixed unit measure. I reviewed your comment and I dont see any conflicts, to clarify how multiple measurements will be aggregated to arrive at one reported value again I am going to measure each index and compare it with itself' before and after 3 different LVC. | 3-6 months post operative | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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CORVIS - Corneal Biomechanics