Collagen Cross-linking in Keratoconus

Study Overview
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Brief Summary
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Optical Coherence Tomography (OCT) devices are non-contact instruments that can measure the depth of scars, other causes of cloudiness of the cornea, and degree of corneal thinning in patients with keratoconus. Laser Custom Corneal Collagen Cross-linking (CXL) significantly decreases corneal aberrations and improves vision. This study will use OCT-guided setting for the lasers used in the corneal smoothing portion of the laser custom CXL procedure to assess the affect on visual outcomes.

Detailed Description
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In the U.S., CXL and topography-guided laser ablation were approved independently, but not together. Another variation in technique involves the use of mitomycin-C (MMC), which is effective in reducing corneal haze after the laser surface ablation. Use of MMC during the laser custom CXL was associated with better outcomes, but in separate trials that could not be directly compared. This study will use OCT measurements to evaluate the magnitudes of direct and indirect laser actions after the procedure.

Official Title
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Clinical Trial of Laser Custom Corneal Collagen Cross-Linking in Keratoconus

Conditions
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Keratoconus

Intervention / Treatment
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* Procedure: Laser Custom Corneal Collagen Cross-Linking


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Diagnosis of keratoconus Minimum corneal thickness of 410 microns Exclusion Criteria: Inability to maintain fixation for OCT imaging Inability to commit to required study visits Inability to give informed consent Eyes with concurrent retinal diseases, glaucoma, or other eye conditions that may limit the visual outcome after surgery Mature cataracts if found to limit visual potential to worse than 20/40

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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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Surgery<br>OCT-guided custom laser CXL | Procedure: Laser Custom Corneal Collagen Cross-Linking<br>* Preoperative measurements from the OCT are used to assist the calculation in deciding the laser depth settings for smoothing the anterior corneal surface and removing any present opacities. The surgeon uses the OCT data to plan treatment parameters while preserving at least 360 microns of residual corneal stroma using a phototherapeutic keratectomy procedure. After the laser procedure, adjunctive MMC or saline solution will be applied to the cornea in accordance with the group to which the treated eye is randomized. The CXL procedure is then performed following the FDA-approved CXL regimen by Avedro, Inc.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Improvement in best spectacle-corrected visual acuity after laser custom CXL | The primary goal of the trial is to determine the extent of visual improvement after laser custom CXL compared to preoperative measurements. Vision will be checked at various time points, but the primary time point will be 6-months post-procedure. | 6 months after the CXL procedure | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Determine CXL demarcation line depth | The study will use OCT imaging to measure the CXL demarcation line inside the entire optical zone. The demarcation line indicates the portion of corneal stroma being cross-linked. This helps determine to what extent the cornea is being strengthened. | 1 month after the CXL procedure | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Keratoconus (KCN), Optical Coherence Tomography (OCT), Collagen Cross-linking (CXL)