Refractive Transepithelial Photo-keratectomy (T-PKR) in High Myopia

Study Overview
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Brief Summary
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The aim of this study is to evaluate the anatomical and refractive parameters following a single-step transepithelial photo-refractive keratectomy (T-PRK) without the addition of mitomycin-C for the treatment of high myopia of 6 diopters or more.

Detailed Description
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In this retrospective study, 69 high myopic eyes of 6 diopters or more were treated in 38 patients by Trans-PRK with the SCHWIND Amaris 500E® excimer laser platform without the use of mitomycin-C. Several outcomes are measured in treated patients, such as postoperative uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), efficacy, safety and predictability of the procedure, as well as corneal haze measurement. The patients are followed-up for 3 months.

Official Title
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Refractive Transepithelial Photo-keratectomy (T-PKR) Without Addition of Mitomycin-C in High Myopia: a Retrospective Study of 69 Eyes

Conditions
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Ophthalmopathy, Myopia, Keratopathy

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age ≥18 years, myopic sphere of -6 diopters or more, astigmatism less than 3 diopters, stable myopia not progressing for more than one year Exclusion Criteria: age <18 years, myopic sphere less than -6 diopters, astigmatism greater than 3 diopters, progressive myopia (variation of more than 0.5 diopters over one year), abnormal corneal topography or the presence of manifest keratoconus, pre-existing eye pathology, history of eye surgery, active inflammatory or infectious eye disease, dermatological disease or systemic connectivitis

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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Postoperative uncorrected visual acuity (UCVA) at week 1 | Postoperative uncorrected visual acuity (UCVA) (logMAR) | Week 1 | 
| Postoperative best spectacle corrected visual acuity (BSCVA) at week 1 | Postoperative best spectacle corrected visual acuity (BSCVA) (logMAR) | Week 1 | 
| Postoperative uncorrected visual acuity (UCVA) at month 1 | Postoperative uncorrected visual acuity (UCVA) (logMAR) | Month 1 | 
| Postoperative uncorrected visual acuity (UCVA) at month 3 | Postoperative uncorrected visual acuity (UCVA) (logMAR) | Month 3 | 
| Postoperative best spectacle corrected visual acuity (BSCVA) at month 1 | Postoperative best spectacle corrected visual acuity (BSCVA) (logMAR) | Month 1 | 
| Postoperative best spectacle corrected visual acuity (BSCVA) at month 3 | Postoperative best spectacle corrected visual acuity (BSCVA) (logMAR) | Month 3 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual acuity efficacy index | The efficacy of the procedure was defined by the proportion of eyes with uncorrected visual acuity at 3 months greater than or equal to Log MAR 0.1 (or 8/10 on a decimal scale). The efficacy index was defined as the ratio between the mean uncorrected visual acuity at 3 months and the best corrected visual acuity preoperatively. A threshold of 80% was required to consider the surgery successful. | 3 months | 
| Visual acuity safety index | The safety of the procedure was defined as the proportion of eyes that lost 2 or more lines of visual acuity compared to the best preoperative corrected visual acuity. The safety index was defined as the ratio between the best corrected visual acuity 3 months postoperatively and the best corrected visual acuity preoperatively. An 80% threshold was chosen to consider the procedure safe. | 3 months | 
| Predictability | Predictability was defined as the percentage of eyes having reached target refraction (± 0.5D) at the end of follow-up (3 months). | 3 months | 
| Postoperative corneal haze measurement at week 1 | Corneal haze assessment was performed at each follow-up visit and reported on the Fantes scale Grade 0: absence of corneal haze. Grade 1: corneal fog that does not prevent the visibility of details of the iris Grade 2: slight fading of details of the iris Grade 3: pronounced erasure of details of the iris and lens Grade 4: complete opacification of the stroma preventing access to the anterior chamber | Week1 | 
| Postoperative corneal haze measurement at month 1 | Corneal haze assessment was performed at each follow-up visit and reported on the Fantes scale Grade 0: absence of corneal haze. Grade 1: corneal fog that does not prevent the visibility of details of the iris Grade 2: slight fading of details of the iris Grade 3: pronounced erasure of details of the iris and lens Grade 4: complete opacification of the stroma preventing access to the anterior chamber | Month 1 | 
| Postoperative corneal haze measurement at month 3 | Corneal haze assessment was performed at each follow-up visit and reported on the Fantes scale Grade 0: absence of corneal haze. Grade 1: corneal fog that does not prevent the visibility of details of the iris Grade 2: slight fading of details of the iris Grade 3: pronounced erasure of details of the iris and lens Grade 4: complete opacification of the stroma preventing access to the anterior chamber | Month 3 | 
| postoperative spherical equivalent | Percent of postoperative spherical equivalent D (SD) | 3 months | 
| Postoperative refractive astigmatism at +/- 0.5D of target | Percent of eyes within +/- 0.5D of target | 3 months | 
| Postoperative refractive astigmatism at +/- 1.0D of target | Percent of eyes within +/- 1.0D of target | 3 months | 
| Complications | Percent of postoperative infections or epithelial healing | Up to 3 months | 
| Patient sex | Sex ratio Men/Women (percent) | Before surgery | 
| Patient age | Age (years) | Before surgery | 
| Preoperative Myopia | Myopia (Diopters) | Before surgery | 
| Preoperative Astigmatism | Astigmatism (Diopters) | Before surgery | 
| Preoperative Spherical equivalence | Spherical equivalence (Diopters) | Before surgery | 
| Preoperative best spectacle corrected visual acuity | BSCVA (logMAR) | Before surgery | 
| Preoperative Keratometry | Keratometry (dipoters) | Before surgery | 
| Preoperative central corneal thickness | central corneal thickness (µm) | Before surgery | 
| Preoperative optical and transition zones | Optical and transition zones (mm) | Before surgery | 
| Preoperative total ablation thickness | Total ablation thickness (µm) | Before surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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high myopia, transepithelial photorefractive keratectomy, mitomycin-C, corneal haze, efficacy, predictibility