Q Value Customized Versus Wavefront Optimized Ablation in Femtosecond Laser-Assisted LASIK

Study Overview
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Brief Summary
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Corneal asphericity is expressed numerically as the Q-value. A minus value means that corneal curvature flattens towards the periphery and the cornea is prolate in shape, but when the curvature steepens towards the periphery, the cornea is oblate in shape and has a positive Q-value. The current study evaluates the effect of LASIK eye surgery on corneal asphericity by comparing 2 software treatment platforms; the Q value customized ablation versus the conventional Wave-front optimized ablation in a fellow eye study pattern.

Detailed Description
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The standard excimer laser correction of myopia is associated with decreased visual quality in the form of a decrease in contrast sensitivity and night vision. This degradation of the visual quality is attributed to changes in the corneal asphericity that increase the high order aberrations (HOAs), such as spherical aberrations because it leads to shifting of the corneal asphericity towards the oblate shape. The wavefront-optimized (WFO) profile avoids the creation of new HOAs, but it is not able to treat those which are already present pre-operatively. The Q-adjusted treatments correct the sphero-cylindrical refractive errors and try to maintain the corneal asphericity at the same time, but like the WFO ablation profiles, it is limited to correcting the spherical aberrations and not the non-rotational symmetric HOAs. Some studies compared Lasers of two different platforms on contralateral eyes of the same patient in order to minimize inter-patient differences such as corneal wound healing and corneal biomechanics. By exclusion of these inter-patient differences, a more accurate judgment on the outcomes can be achieved.

Official Title
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Q Value Customized Versus Wavefront Optimized Ablation in Femtosecond Laser-Assisted LASIK for Myopia and Myopic Astigmatism. A Contralateral Comparative Study

Conditions
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Patients With Myopic Spherical Equivalent up to -12 Diopters

Intervention / Treatment
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* Procedure: Femtosecond laser assisted LASIK eye surgery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Candidates for Laser vision correction (LVC) with Myopic Spherical Equivalent up to -12 diopters. Myopic astigmatism up to -6 diopters. Corneal thinnest location ≥ 500 um 4- Residual stromal bed ≥ 300 um. Exclusion Criteria: Patients not candidates for LVC. Hyperopic patients or mixed astigmatism. Systemic disease that contraindicates LVC. Intra- or post-operative complications. 5- Previous corneal surgery

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: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Custom Q treatment group<br>For every patient, the eye with the greater myopic spherical equivalent (SE) will be assigned for the Custom-Q treatment group. | Procedure: Femtosecond laser assisted LASIK eye surgery<br>* FS-LASIK eye surgery includes corneal flap creation with femtosecond laser using the Femtosecond laser WaveLight FS200 followed by excimer laser vision correction of the patient's refractive error using excimer laser WaveLight EX500.<br>|
| Active Comparator: Wave-front optimized (WFO) group<br>For every patient, the other eye with the lesser myopic SE will be assigned for the WFO treatment group | Procedure: Femtosecond laser assisted LASIK eye surgery<br>* FS-LASIK eye surgery includes corneal flap creation with femtosecond laser using the Femtosecond laser WaveLight FS200 followed by excimer laser vision correction of the patient's refractive error using excimer laser WaveLight EX500.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postoperative Q value | Pentacam evaluation of post-LASIK Q value | 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postoperative corneal thickness at the pupillary center | Pentacam evaluation of post-LASIK pachymetry at the pupil center | 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Femtosecond LASIK, Q value, Wave-front Optimized (WFO)