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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
50
Used for corneal wavefront guided PRK therapeutic ablation (50 µm) or for PTK epithelial removal, according to arm assignment.
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 \[equivalent to 3 minutes "on" time\].
Instituto de Oftalmología FAP Conde de Valenciana, IAP Sede Centro
Mexico City, Mexico City, Mexico
RECRUITINGChange 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.
Time frame: Baseline to 12 months
Change in Kmax (Diopters)
Pentacam Scheimpflug tomography; maximum keratometry (D); change from baseline at each time point.
Time frame: Baseline; 3; 6; 12 months
Change in corneal higher-order aberrations (µm RMS)
Wavefront/aberrometry total HOAs RMS (µm) over 6-mm pupil; change from baseline.
Time frame: Baseline; 3,6,12 months
Change in manifest refraction spherical equivalent (Diopters)
Manifest refraction SE (D); change from baseline.
Time frame: 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.
Time frame: 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
Time frame: 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.
Time frame: 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.
Time frame: 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).
Time frame: 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.
Time frame: Baseline; 3; 6; 12 months
Corvis ST metric: Inverse Concavity Radius
Inverse Concavity Radius as measured by Corvis ST. Unit of measure: mm
Time frame: Baseline; 3; 6; 12 months
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