Contoura vs Wavefront Optimized Ablation

Study Overview
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Brief Summary
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To evaluate the efficacy, safety and accuracy of Contoura topography-guided LASIK & PRK in comparison to Wavefront optimized LASIK & PRK in virgin eyes with astigmatism.

Detailed Description
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In Upper Egypt, The second principal cause of blindness was uncorrected refractive errors accounting for 16% of sample population. It was reported that astigmatism (defined as cylinder power > 0.5 D) was the most common refractive errors in children and adults followed by hyperopia and myopia. Laser vision correction has been established over the last 2 decades as a safe and effective intervention to treat refractive errors, being one of the main techniques practiced globally. However, many subjects after LASIK had uncorrected distance visual acuity (UDVA) greater than 1.0, they complain about poor night vision, glare, and double vision. As studies have shown that every 1° deviation of the astigmatic axis could result in loss of correction of 3.3%. Even residual astigmatism less than 0.50D could have an actual impact on visual quality. Excimer laser ablation used in the correction of refracted errors especially astigmatism may reduce quality of vision, and that is attributed to the induced optical aberrations. The most prevalent of these optical aberrations is the spherical aberration. Among multiple sophisticated profiles that developed to optimize visual outcomes, wavefront optimized profile which compensate for corneal curvature to reduce spherical aberration. The topographic guided profiles which consider the shape of the anterior corneal surface. Contoura topography guided ablation corrects astigmatic power and axis to create a more uniform, aberration-free cornea. Treating astigmatism can be challenging as the conventional patterns of Excimer laser treatment of astigmatism is known to be less predictable than that of spherical refractive errors.

Official Title
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Contoura Topography-guided Ablation Versus Wavefront-optimized Ablation for Correction of Astigmatism

Conditions
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Astigmatism

Intervention / Treatment
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* Procedure: Laser assisted in-situ keratomileusis
* Procedure: Photorefractive keratectomy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Astigmatism (up to 5.0 diopters) or less. Central corneal thickness (CCT) of 500 microns or more Estimated Residual stromal bed thickness (RSB) of 280 microns or more Subject has provided written informed consent Exclusion Criteria: Keratoconus Abnormal topography previous ocular trauma or eye surgery pre-existing diseases of the vitreous, macula, or optic nerve that can affect visual outcome patients with uveitis and anterior segment pathology patients with corneal pathology or Severe dry eye pregnancy or breast-feeding females uncontrolled vascular or autoimmune disease

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Group A<br>Contoura topography-guided LASIK | Procedure: Laser assisted in-situ keratomileusis<br>* Laser-Assisted In Situ Keratomileusis is a procedure that permanently changes the shape of the cornea using an excimer laser and the mechanical microkeratome (a blade device) used to cut a flap in the cornea.<br>* Other names: LASIK;|
| Group B<br>Contoura topography-guided PRK | Procedure: Photorefractive keratectomy<br>* Photorefractive keratectomy is a laser refractive procedure used to ablate the corneal stroma to correct refractive errors without cutting flap<br>* Other names: PRK;|
| Group C<br>Wavefront-optimized LASIK | Procedure: Laser assisted in-situ keratomileusis<br>* Laser-Assisted In Situ Keratomileusis is a procedure that permanently changes the shape of the cornea using an excimer laser and the mechanical microkeratome (a blade device) used to cut a flap in the cornea.<br>* Other names: LASIK;|
| Group D<br>Wavefront-optimized PRK | Procedure: Photorefractive keratectomy<br>* Photorefractive keratectomy is a laser refractive procedure used to ablate the corneal stroma to correct refractive errors without cutting flap<br>* Other names: PRK;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Postoperative UDVA compared to preoperative CDVA (in LogMAR) | UCVA 3 month after surgery compared to baseline preoperative CDVA | 3 month | 
| Number of lines of preoperative CDVA compared to postoperative | Change in lines of CDVA from baseline preoperative to 3 month postoperative (in LogMAR) | 3 month | 
| Amount of Residual Astigmatism postoperatively (in Diopters) | residual astigmatism 3 month postoperatively | 3 month | 
| Postoperative mean spherical equivalent MSE compared to Preoperative MSE (in Diopters) | changes in mean spherical equivalent baseline preoperative to 3 month postoperative | 3 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Contrast sensitivity test |  | 3 month | 
| Amount of High order aberrations | (Spherical aberration, trefoil, vertical & horizontal coma) | 3 month | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Contoura, Wavefront optimized ablation, LASIK, PRK