Treatment of Keratoconus With Advanced Corneal Crosslinking

Study Overview
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Brief Summary
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The purpose of this study was to determine whether mechanical compression of the cornea during corneal crosslinking for keratoconus using a sutured rigid contact lens can improve the optical outcomes of the treatment.

Detailed Description
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The study is designed as a prospective, open, randomized controlled trial involving patients aged 18-28 years of both genders with uni- or bilateral keratoconus planned for routine corneal crosslinking at the Department of Ophthalmology, Umeå University Hospital, Umeå, Sweden. The study involves 30+30 eyes with keratoconus, which are randomized to receive either conventional corneal crosslinking (n=30) using the Dresden protocol or a modified treatment - corneal reshaping and crosslinking (n=30), where a rigid contact lens is sutured to the cornea during the treatment to flatten the corneal curvature and potentially improve the optical outcome after the treatment. Patients are randomized utilizing a list of unique random numbers between 1 and 60. All patients are informed about the procedures before consenting to participate in the study. The study also involves 60 eyes of healthy age- and sex-matched control subjects. At baseline, before treatment, each eye is evaluated with autorefractometer measurement, best spectacle-corrected LogMAR visual acuity, Pentacam Scheimpflug photography, Goldmann applanation tonometry and biomicroscopy. The corneal biomechanical characteristics are assessed with applanation resonance tonometry and the ocular response analyzer. The investigations are repeated at 1 month, 6 months, 2 years and 5 years after the treatment.

Official Title
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Treatment of Keratoconus With Advanced Corneal Crosslinking

Conditions
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Keratoconus

Intervention / Treatment
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* Procedure: Corneal reshaping/crosslinking (CRXL)
* Procedure: Corneal Crosslinking (CXL)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients planned for corneal crosslinking. Progressive keratoconus documented with Scheimpflug photography using the Pentacam Scheimflug camera and/or repeated subjective refraction and keratometry. A keratoconus diagnosis based on the Amsler-Krumeich grading and the Total Deviation KC quantification value from the Belin-Ambrosio enhanced ectasia measurements of the Pentacam Scheimpflug camera, and an altered red reflex and/or an irregular cornea seen as distortion of the keratometric mires. Minimum corneal thickness of 400 µm at the thinnest point after epithelial removal. 18-28 years of age No ocular abnormalities except keratoconus No previous ocular surgery No cognitive insufficiency interfering with the informed consent. Exclusion Criteria: Age under 18 or over 28 Any corneal abnormalities except keratoconus Previous ocular surgery Cognitive insufficiency.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 28 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Corneal reshaping/crosslinking (CRXL)<br>Corneal crosslinking with compression of the cornea using a sutured rigid contact lens during the treatment. | Procedure: Corneal reshaping/crosslinking (CRXL)<br>* The keratoconus cornea is treated with epithelial debridement in local anesthesia, is soaked in Riboflavin by repeated topical application during 30 minutes. A flat, rigid contact lens is sutured to the cornea and the cornea and is then irradiated with ultraviolet light 5.4 J/cm2 during 30 minutes.<br>|
| Active Comparator: Corneal crosslinking (CXL)<br>Standard corneal crosslinking using the Dresden protocol. | Procedure: Corneal Crosslinking (CXL)<br>* The keratoconus cornea is treated with epithelial debridement in local anesthesia, is soaked in Riboflavin by repeated topical application during 30 minutes. The cornea and is then irradiated with ultraviolet light 5.4 J/cm2 during 30 minutes.<br>|
| No Intervention: Control group to CRXL<br>Healthy subjects, age- and sex-matched to the CRXL group. | |
| No Intervention: Control group to CXL<br>Healthy subjects, age- and sex-matched to the CXL group. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in refraction | Refractive errors, including lower and higher order aberrations in the cornea | 1, 6, 24 and 60 months after the treatment | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in ETDRS LogMAR visual acuity | Uncorrected and best spectacle corrected visual acuity measured with the Early treatment diabetic retinopathy study, graded in logarithmic values of the minimal angle of resolution | 1, 6, 24 and 60 months after the treatment | 
| Change from baseline in corneal biomechanical stability measured with ORA | Biomechanical stability assessed with the ocular response analyzer | 1, 6, 24 and 60 months after the treatment | 
| Change from baseline in corneal biomechanical stability measured with ART | Biomechanical stability assessed with the applanation resonance tonometer | 1, 6, 24 and 60 months after the treatment | 
| Change from baseline in corneal biomechanical stability measured with GAT | Biomechanical stability assessed with the Goldmann applanation tonometer | 1, 6, 24 and 60 months after the treatment | 
| Change from baseline in corneal densitometry | Corneal light reflectivity (back scatter) assessed with the Pentacam HR Scheimpflug camera | 1, 6, 24 and 60 months after the treatment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Corneal crosslinking, Corneal biomechanics, Keratoconus, Corneal densitometry, Scheimpflug photography