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Keratoconus causes irregular astigmatism and reduced vision. Epi-off corneal crosslinking (CXL) stabilizes the cornea but often leaves higher-order aberrations uncorrected. This randomized, parallel-group trial compares corneal wavefront guided photorefractive keratectomy (corneal wavefront guided PRK, 50 µm therapeutic ablation) combined with accelerated epi-off CXL versus epi-off CXL with epithelial removal by phototherapeutic keratectomy (PTK) using a Schwind AMARIS excimer laser, in adults with keratoconus. The primary endpoint is change in best-corrected distance visual acuity (logMAR) at 12 months. Key secondary endpoints include Kmax, corneal higher-order aberrations, manifest refraction, Scheimpflug densitometry (haze) and Fantes grade, Corvis ST biomechanics, NEI VFQ-25, and endothelial cell density by non-contact specular microscopy at 1, 3, 6 and 12 months.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Corneal Wavefront Guided PRK + CXL | Experimental | Corneal wavefront guided therapeutic PRK (50 µm) with Schwind AMARIS, followed by accelerated epi-off CXL. Intensity: 30 mW/cm² (pulsed 1 s on / 1 s off; 50% duty cycle). Total energy (fluence): 5.4 J/cm². Total time (elapsed): 6 minutes [equivalent to 3 minutes "on" time]. |
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| PTK + CXL | Active Comparator | Epithelial removal by PTK using Schwind AMARIS, followed by accelerated epi-off CXL. Intensity: 30 mW/cm² (pulsed 1 s on / 1 s off; 50% duty cycle). Total energy (fluence): 5.4 J/cm². Total time (elapsed): 6 minutes [equivalent to 3 minutes "on" time]. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Schwind AMARIS excimer laser | Device | Used for corneal wavefront guided PRK therapeutic ablation (50 µm) or for PTK epithelial removal, according to arm assignment. |
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| Measure | Description | Time Frame |
|---|---|---|
| Change in best-corrected distance visual acuity (logMAR) | ETDRS-based CDVA in logMAR; change from baseline at 12 months; primary analysis by ANCOVA adjusted for baseline; one study eye per participant. | Baseline to 12 months |
| Measure | Description | Time Frame |
|---|---|---|
| Change in Kmax (Diopters) | Pentacam Scheimpflug tomography; maximum keratometry (D); change from baseline at each time point. | Baseline; 3; 6; 12 months |
| Change in corneal higher-order aberrations (µm RMS) |
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Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Instituto de Oftalmología FAP Conde de Valenciana, IAP Sede Centro | Recruiting | Mexico City | Mexico City | 06800 | Mexico |
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| ID | Term |
|---|---|
| D007640 | Keratoconus |
| D003318 | Corneal Opacity |
| ID | Term |
|---|---|
| D003316 | Corneal Diseases |
| D005128 | Eye Diseases |
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| Corneal collagen crosslinking epi-off accelerated | Procedure | Riboflavin-UVA crosslinking performed after epithelial removal (corneal wavefront guided PRK arm via PRK; comparator arm via PTK). Intensity: 30 mW/cm² (pulsed 1 s on / 1 s off; 50% duty cycle). Total energy (fluence): 5.4 J/cm². Total time (elapsed): 6 minutes [equivalent to 3 minutes "on" time]. |
|
Wavefront/aberrometry total HOAs RMS (µm) over 6-mm pupil; change from baseline.
| Baseline; 3,6,12 months |
| Change in manifest refraction spherical equivalent (Diopters) | Manifest refraction SE (D); change from baseline. | Baseline; 3;6;12 months |
| Corneal haze (Scheimpflug densitometry units) | CCT and corneal haze as measured by Pentacam Corneal Densitometry. Unit of measure: gray units. | Baseline; 3;6;12 months |
| Corvis ST metric: Ambrosio Relational Thickness horizontal (ART-h) | ART-h as measured by Corvis ST. Unit of measure: microns | Baseline; 3,6; 12 months |
| Visual Functioning Questionnaire (NEI VFQ-25) | NEI VFQ-25 composite and subscale scores computed per scoring manual; change from baseline. 0 to 100, where higher scores indicate better vision-related quality of life. | Baseline; 6;12 months |
| Endothelial cell density (cells/mm²; specular microscopy) | Non-contact specular microscopy; primary metric = endothelial cell density (cells/mm²); secondary metrics (if collected) = coefficient of variation and hexagonality; change from baseline; one study eye per participant. | Baseline; 1; 3; 6; 12 months |
| Serious corneal adverse events | Incidence of protocol-defined serious ocular AEs ( infectious keratitis, perforation, persistent epithelial defect >14 days, ≥20% endothelial cell density loss, visually significant stromal scarring requiring surgery). | Baseline to 12 months |
| Corneal haze (Fantes grade) | Fantes clinical haze grade (ordinal); recorded at each visit. Units: Fantes grade. Scale: 0-4 scale, higher scores = worse haze. | Baseline; 3; 6; 12 months |
| Corvis ST metric: Inverse Concavity Radius | Inverse Concavity Radius as measured by Corvis ST. Unit of measure: mm | Baseline; 3; 6; 12 months |