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NCT Number: NCT07372911

PRoTECT: Corneal Wavefront Guided PRK + Epi-off CXL vs. PTK+Epi-off CXL in Keratoconus

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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Key information

Conditions

Keratoconus Corneal Diseases Corneal Opacity Eye Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Instituto de Oftalmología FAP Conde de Valenciana, IAP Sede Centro

Mexico City, 06800, Mexico

Location status: Recruiting

Location contact

José Carlos JC Guerrero Acosta, MD

CONTACT

[email protected]

3314662291

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Schwind AMARIS excimer laser

Device

Used for corneal wavefront guided PRK therapeutic ablation (50 µm) or for PTK epithelial removal, according to arm assignment.

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].

Primary outcomes

  1. 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

  1. Change in Kmax (Diopters)

    Time frame: Baseline; 3; 6; 12 months

    Pentacam Scheimpflug tomography; maximum keratometry (D); change from baseline at each time point.

  2. Change in corneal higher-order aberrations (µm RMS)

    Time frame: Baseline; 3,6,12 months

    Wavefront/aberrometry total HOAs RMS (µm) over 6-mm pupil; change from baseline.

  3. Change in manifest refraction spherical equivalent (Diopters)

    Time frame: Baseline; 3;6;12 months

    Manifest refraction SE (D); change from baseline.

  4. Corneal haze (Scheimpflug densitometry units)

    Time frame: Baseline; 3;6;12 months

    CCT and corneal haze as measured by Pentacam Corneal Densitometry. Unit of measure: gray units.

  5. Corvis ST metric: Ambrosio Relational Thickness horizontal (ART-h)

    Time frame: Baseline; 3,6; 12 months

    ART-h as measured by Corvis ST. Unit of measure: microns

  6. Visual Functioning Questionnaire (NEI VFQ-25)

    Time frame: Baseline; 6;12 months

    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.

  7. Endothelial cell density (cells/mm²; specular microscopy)

    Time frame: Baseline; 1; 3; 6; 12 months

    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.

  8. Serious corneal adverse events

    Time frame: Baseline to 12 months

    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).

  9. Corneal haze (Fantes grade)

    Time frame: Baseline; 3; 6; 12 months

    Fantes clinical haze grade (ordinal); recorded at each visit. Units: Fantes grade. Scale: 0-4 scale, higher scores = worse haze.

  10. Corvis ST metric: Inverse Concavity Radius

    Time frame: Baseline; 3; 6; 12 months

    Inverse Concavity Radius as measured by Corvis ST. Unit of measure: mm

Sponsors and collaborators

Lead sponsor

Instituto de Oftalmología Fundación Conde de Valenciana

Other

Registry information

Official study title

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

Acronym: PRoTECT

Important dates

Study start
2025
Primary completion
2026
Study completion
2027
First posted
Jan 28, 2026
Registry last updated
Jan 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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