Corneal Topography Asymmetry Indices Changes After Corneal Refractive Surgery

Study Overview
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Brief Summary
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To evaluate the changes that occur in the corneal indices after corneal refractive surgery either PRK or LASIK.

Detailed Description
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Retrospectively review the medical records of all patients who underwent refractive surgery referred from the out-patient clinic of Tanta University hospital between September 2015 and September 2020 . Data collection will include: Preoperative and postoperative Evaluation: Age, sex, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest and cycloplegic refraction, Slit lamp biomicroscopy, fundus examination. Data of Corneal Tomography keratometric using Scheimpflug camera (Pentacam Oculus- Germany) :that includes the following indices Average keratometric value (K mean) in diopters Maximum simulated keratometry (Kmax) in diopters Index of Surface Variance (ISV) in microns Index of Vertical Asymmetey (IVA) in microns Radii Minimum (R min) in microns Index of height asymmetry (IHA) in microns Index of height decantation (IHD) in microns Aberration coefficient (ABR) The data of the pentacam will be collected pre-operative and analyzed at 1 month, 3 months and 6 months with recording of the complications.

Official Title
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Corneal Topography Asymmetry Indices Changes After Corneal Refractive Surgery

Conditions
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Myopia

Intervention / Treatment
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* Other: Refractive surgery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients who underwent refractive surgery either PRK, LASIK with age between 19 and 35 years old Exclusion Criteria: Kertoconus. Corneal scarring. Previous corneal infections. Minimum corneal thickness at the thinnest location less than 400 µm. History of uveitis or ocular allergy. Pre-existing glaucoma. Data not available

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Group(1): Patient who underwent PRK<br> | Other: Refractive surgery<br>* Refractive surgery for correction of error of refraction<br>|
| Group(2): Patient underwent LASIK<br> | Other: Refractive surgery<br>* Refractive surgery for correction of error of refraction<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To evaluate the changes that occur in the corneal indices after corneal refractive surgery either PRK or LASIK. | Using the results of measurements of Scheimpflug camera (Pentacam Oculus- Germany) :that includes the following indices Average keratometric value (K mean) in diopters Maximum simulated keratometry (Kmax) in diopters Index of Surface Variance (ISV) in microns Index of Vertical Asymmetey (IVA) in microns Radii Minimum (R min) in microns Index of height asymmetry (IHA) in microns Index of height decantation (IHD) in microns Aberration coefficient (ABR) The numbers from preoperative records will be compared with postoperative records after the refractive surgery is done . All the values will be expressed as mean ± standard deviation and the data will be analyzed as 1 months, 3 months and 6 months after surgery | 6 months |