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KeratoconusPhase 3CXL-RCTNCT01604135

Collagen Crosslinking for Keratoconus - a Randomized Controlled Clinical Trial

A Phase 3 study testing Corneal Collagen Crosslinking in people with Keratoconus, run by Sahlgrenska University Hospital at 1 site in Sweden.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

The purpose of this study is to determine whether corneal collagen crosslinking is effective in the treatment of progressive keratoconus. Read more about this study

Who is it for?
Ages 18 to 30 years
Conditions the study is for
Keratoconus
What is being tested?
Corneal Collagen Crosslinking
Type of treatment
Medical device
Could I receive a placebo?
No, everyone receives an active treatment
How many people
36 participants
Where
1 siteSweden
Study dates
May 2012to Apr 2027
Phase
Phase 3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 30 years
  • All sexes
  • No healthy volunteers
  • Adult

Who may be able to join

  • Keratoconus diagnosis determined clinically and topographically (KISA%- index)
  • Significant progression is defined as change (increase) of Kmax by at least
  • 1D from baseline at 6 months and/or change (increase) of Sim-K-ast by at least 1D from baseline at 6 months. Kmax is defined as the steepest radius of curvature (either the maximum simulated K-reading or the maximum K-reading in the 3-mm zone or the 5-mm zone) of the anterior corneal surface that progressed the most during 6 months observation
  • Ability to stop contact lens (rigid and soft) wear at least two weeks prior to next exam
  • Signed written informed consent

Who cannot join

  • Age < 18 years
  • Pregnancy
  • Breast feeding
  • History of corneal surgery
  • History of ocular herpes simplex infection
  • Minimal corneal thickness < 300 micrometers
Show all 16Show fewer
  • Recurrent corneal erosions
  • Other corneal (e g endothelial) or conjunktival diseases
  • Neurodermatitis
  • Severe forms av atopic disease
  • Collagenoses, autoimmune or other systemic disease
  • Systemic treatment with high doses of steroids
  • Severe scarring och striae of the cornea
  • Relative exclusion criteria:
  • Kmax > 58D
  • Minimal corneal thickness < 400 micrometers (a modified CXL-treatment will be used swelling the cornea before UV-illumination treatment).

Trial locations and contacts

1 site in 1 country.

Sweden1 site

  • Department of Ophthalmology, Sahlgrenska University Hospital

    Mölndal, Västra Götalandsregionen, 43180

Other trials in Sweden

About this study

The purpose of this study is to determine whether corneal collagen crosslinking is effective in the treatment of progressive keratoconus.

Read the detailed description

Keratoconus is a noninflammatory, asymmetrical, progressive corneal ectasia caused by biomechanical instability of the corneal stroma. Treatment modalities are primarily glasses or contact lenses. It has been estimated that one out of five patients will progress to such an extent that a corneal transplant is necessary to regain useful vision.

Corneal collagen crosslinking (CXL) is a treatment modality that intends to halt progression of keratoconus. This study investigates the efficacy av CXL in stabilizing the cornea in keratoconus by means of a randomized controlled clinical trial.

Participants are eligible for inclusion if progressive keratoconus is confirmed and the inclusion criteria are met. Follow-up after inclusion is at 1 week (treatment group), 1, 3, 6 and 12 months. Pre- and post-inclusion examinations include measurement of uncorrected distance visual acuity (UCDVA), best spectacle corrected distance visual acuity (BSCDVA), Scheimpflug-topography and slitlamp examination.

Conditions
Keratoconus
Being tested
Corneal Collagen Crosslinking
Keywords
Collagen crosslinking, Keratoconus
Medical subject headings
Keratoconus

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Corneal Collagen CrosslinkingDevice

    Also called Cross-Linking Procedure UV-X 2000, UV-X 2000 Illumination system, Innocross-R 0.1% dextran 20% solution, Innocross-R hypotonic riboflavin 0.1%

    Keratoconic corneas that show significant progression as specified in the inclusion criteria section will receive one single treatment with CXL if randomized to the treatment arm. A treatment protocol based on 30 minutes dropping with riboflavin/dextran solution and 10 minutes UV-illumination treatment will be used.

Study groups in NCT01604135
Study groupRoleWhat they receive
Corneal Collagen CrosslinkingActive comparatorThe keratokonic eye which progresses most is included and randomized. Significant progression is defined in the eligibility criteria section. If randomized to the treatment arm the cornea is treated with collagen crosslinking as described below.
Receives: Device: Corneal Collagen Crosslinking
Control groupNo interventionThe keratokonic eye which progresses most is included and randomized to either the treatment group (CXL) or the control group.

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Kmax

    Kmax is defined as the steepest radius of curvature of the anterior corneal surface. It is measured by Scheimpflug-topography (Pentacam, Oculus Inc.). An increase of less than 1 diopter (D) from baseline at 12 months is defined as non-progression.

    Measured: 12 months

Secondary outcomes (4)

  1. Sim-K-astigmatism

    Sim-K-astigmatism (Sim-K-ast) is defined as the absolute amount of anterior corneal astigmatism related to the Sim-Ks as measured by Scheimpflug-topography (Pentacam, Oculus Inc.). An increase of less than 1 D from baseline at 12 months is defined as non progression.

    Measured: 12 months

  2. MRSE

    Manifest Refractive Spherical Equivalent. The spherical equivalent is calculated by algebraic addition of the spherical power and half the cylindrical power of an eye. An eye with a specific spherical equivalent power has the closest overall effect to a given toric lens. A decrease of less than 0.5 D from baseline at 12 months is defined as non-progression.

    Measured: 12 months

  3. UCDVA

    UCDVA is defined as the uncorrected distance visual acuity measured with an Early Treatment of Diabetic Retinopathy Study (ETDRS)-chart and expressed in numbers of letters. A decrease of less than 5 letters (one line) from baseline at 12 months is defined as stable BCDVA.

    Measured: 12 months

  4. BSCDVA

    BSCDVA is defined as the the best spectacle corrected distance visual acuity measured with an ETDRS-chart and expressed in numbers of letters. A decrease of less than 5 letters (one line) from baseline at 12 months is defined as stable BCDVA.

    Measured: 12 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted23 May 2012 (estimated)
  2. Study startMay 2012
  3. Primary completionApr 2027 (estimated)
  4. Study completionApr 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
36 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT01604135
Sponsor's protocol ID
DNR-949-11
Acronym
CXL-RCT
Status last verified
May 2026
First submitted
21 May 2012
Last updated
11 May 2026
Results posted
No
Data monitoring committee
Yes
Individual data sharing
No

Publications

  • Hersh PS, Greenstein SA, Fry KL. Corneal collagen crosslinking for keratoconus and corneal ectasia: One-year results. J Cataract Refract Surg. 2011 Jan;37(1):149-60. doi: 10.1016/j.jcrs.2010.07.030.

    PubMed 21183110

  • Greenstein SA, Fry KL, Hersh PS. Corneal topography indices after corneal collagen crosslinking for keratoconus and corneal ectasia: one-year results. J Cataract Refract Surg. 2011 Jul;37(7):1282-90. doi: 10.1016/j.jcrs.2011.01.029.

    PubMed 21700105

  • Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003 May;135(5):620-7. doi: 10.1016/s0002-9394(02)02220-1.

    PubMed 12719068

  • Wittig-Silva C, Chan E, Islam FM, Wu T, Whiting M, Snibson GR. A randomized, controlled trial of corneal collagen cross-linking in progressive keratoconus: three-year results. Ophthalmology. 2014 Apr;121(4):812-21. doi: 10.1016/j.ophtha.2013.10.028. Epub 2014 Jan 6.

    PubMed 24393351

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Corneal Collagen Crosslinking in people with Keratoconus, run by Sahlgrenska University Hospital at 1 site in Sweden.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 5 inclusion and 16 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 11 May 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Sweden. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Kmax (time frame: 12 months). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT01604135, which also lists 4 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 May 2026.

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