Topography-Guided Customized PRK Versus Q-value Adjusted PRK in Correction of Myopia With or Without Astigmatism

Study Overview
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Brief Summary
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This study will include patients who will undergo PRK in both eyes, for each patient each eye will be randomly allocated to one of 2 procedures: topography-guided ablation in one eye (group I) and Q-factor customized ablation in the other eye (group II). Alcon/Wavelight Light Laser Technolo¬gie (GmbH, Erlangen, Germany) will be used for photoablation. The wavelight Topolyzer (Wavelight AG, Erlan¬gen, Germany)and CSO Sirius scheimpflug camera combined with Placido corneal topography (CSO, Florence,Italy) will be used before and 1, 3 and 6 months after PRK. Refrac¬tive visual outcomes and corneal aberration changes will be compared between the two treatment modalities.

Official Title
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Topography-Guided Customized PRK (Photorefractive Keratectomy) Versus Q-value Adjusted PRK in Correction of Myopia With or Without Astigmatism

Conditions
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Myopia

Intervention / Treatment
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* Procedure: PRK


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age more than 18 years Myopia with up to -6.5 D with or without astigmatism up to -4.75 D Exclusion Criteria: anterior segment abnormalities (ie, cataracts, corneal scarring) basement membrane disease history of recurrent corneal erosions Schirmer's test less than 5 mm established or forme fruste keratoconus macular or retinal disease current use of immunosuppressive therapy autoimmune disease pregnancy, and lactation

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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No

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: topography guided PRK in one eye<br>Topography-guided (placido disk- based) using T-CAT Contoura treatment. | Procedure: PRK<br>* PRK using Alcon-Wavelight Excimer Laser EX 500<br>|
| Active Comparator: Q-value adjusted ( custom Q) PRK in the other eye<br>The target Q will be estimated according to a nomogram considering the patient's age | Procedure: PRK<br>* PRK using Alcon-Wavelight Excimer Laser EX 500<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in Postoperative spherical equivalent depending on manifest refraction after autorefractometer |  | 1 , 3 and 6 months postoperative | 
| change in visual acuity using snellen chart |  | 1 , 3 and 6 months postoperative | 
| change in corneal wavefront aberrations | assessed by topolyzer | 1 , 3 and 6 months postoperative | 
| change in Q value anterior at 6mm RMS, RMS of astigmatism, RMS of coma and RMS of spherical aberrations. Strehl ratio : Qvalue,RMS,strehl ratio by CSO Sirius scheimpflug | by CSO Sirius scheimpflug | 1,3 and 6months | 
| change in total RMS | by CSO Sirius scheimpflug | 1,3 and 6months | 
| change in strehl ratio | by CSO scheimpflug | 1,3 and 6 months | 
| change in Q value | assessed by topolyzer | 1,3 and 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| efficacy:ratio of postoperative decimal UDVA to preoperative decimal CDVA | ratio of postoperative decimal UDVA to preoperative decimal CDVA | 6 months | 
| contrast sensitivity | cambridge low contrast sensitivity | 6 months | 
| predictability | eyes within 1.0 D of emmetropia | 6 months | 
| safety:ratio of mean preoperative decimal CDVA to mean postoperative decimal CDVA | ratio of mean preoperative decimal CDVA to mean postoperative decimal CDVA | 6 months | 
| stability | change of more than 0.5D over | 6 months |