Corneal Wavefront Guided PRK Combined With Epi-off Corneal Cross-Linking Versus Epi-off Corneal Cross-Linking With PTK Epithelial Removal in Keratoconus: A Randomized Clinical Trial
Trial Snapshot
- Phase
- Not Applicable
- Status
- Recruiting
- Sponsor
- Enrollment
- 50
- Locations
- 1
- Primary Endpoint
- Change in best-corrected distance visual acuity (logMAR)
Study Overview
Brief Summary
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.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Treatment
- Masking
- Double (Participant, Outcomes Assessor)
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Age 18-40 years
- •Diagnosis of keratoconus, ABCD Belin stage I-III at baseline
- •Minimum (thinnest) corneal pachymetry ≥ 450 µm pre-op
- •Written informed consent
- •Age-stratified progression requirements:
- •18-25 y: keratoconus stage I-III (progression not mandatory)
- •25-35 y: documented progression (meet ≥ 2 Table-1 criteria below) or, if recent documentation is absent, high-risk features for future progression: Kmax > 53 D, strong family history, severe atopy with persistent eye rubbing, or any of the following over 12 months: ΔKmax ≥ 1.0 D, thinnest pachymetry decrease ≥ 10 µm, or increase in manifest cylinder ≥ 1.0 D
- •35-40 y: clear, unequivocal recent progression (meet ≥ 2 Table-1 criteria); late-onset documented progression may be considered
Exclusion Criteria
- •Central corneal scars or opacities
- •Prior ocular surgery or trauma (exception: prior LASIK if it is the cause of post-surgical ectasia, per protocol text)
- •Autoimmune disease or uncontrolled diabetes mellitus
- •Pregnancy or lactation
- •Contact lens wear within 2 weeks before baseline evaluation
Arms & Interventions
Corneal Wavefront Guided PRK + CXL
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].
Intervention: Schwind AMARIS excimer laser (Device)
Corneal Wavefront Guided PRK + CXL
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].
Intervention: Corneal collagen crosslinking epi-off accelerated (Procedure)
PTK + CXL
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].
Intervention: Schwind AMARIS excimer laser (Device)
PTK + CXL
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].
Intervention: Corneal collagen crosslinking epi-off accelerated (Procedure)
Outcomes
Primary Outcomes
Change in best-corrected distance visual acuity (logMAR)
Time Frame: Baseline to 12 months
ETDRS-based CDVA in logMAR; change from baseline at 12 months; primary analysis by ANCOVA adjusted for baseline; one study eye per participant.
Secondary Outcomes
- Change in Kmax (Diopters)(Baseline; 3; 6; 12 months)
- Change in corneal higher-order aberrations (µm RMS)(Baseline; 3,6,12 months)
- Change in manifest refraction spherical equivalent (Diopters)(Baseline; 3;6;12 months)
- Corneal haze (Scheimpflug densitometry units)(Baseline; 3;6;12 months)
- Corvis ST metric: Ambrosio Relational Thickness horizontal (ART-h)(Baseline; 3,6; 12 months)
- Visual Functioning Questionnaire (NEI VFQ-25)(Baseline; 6;12 months)
- Endothelial cell density (cells/mm²; specular microscopy)(Baseline; 1; 3; 6; 12 months)
- Serious corneal adverse events(Baseline to 12 months)
- Corneal haze (Fantes grade)(Baseline; 3; 6; 12 months)
- Corvis ST metric: Inverse Concavity Radius(Baseline; 3; 6; 12 months)