KeratoconusNCT00560651

German Corneal Cross Linking Register

An observational study of Keratoconus, run by Suphi Taneri at 2 sites in Germany.

Active, not recruiting

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

Trial summary

Corneal Cross Linking is new treatment modality for patients with keratoconus. A keratoconus is characterized by progressive bulging and thinning of the eye's cornea. Keratoconus is a potentially severely sight impairing condition that may necessitate corneal transplantation in the progressive state. Read more about this study

Who is it for?: Any age
Conditions the study is for: Keratoconus
What is being tested?: CCL (Corneal Cross Linking)
Type of treatment: Surgery or procedure
How many people: 356 participants
Where: 2 sitesGermany
Study dates: Nov 2007to Nov 2027
Phase: Observational
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 Any age
All sexes
No healthy volunteers
Child, Adult, Older adult

Study population: Patients treated with Corneal Cross Linking in Germany

Who may be able to join

Patients diagnosed with keratokonus and treated with corneal cross Linking in Germany

Who cannot join

Non-ectatic conditions

Trial locations and contacts

2 sites in 1 country.

Germany2 sites

University of Saar
Homburg, 66421
Augenklinik am St. Franziskus Hospital
Münster, 48145

Other trials in Germany

About this study

Corneal Cross Linking is designed to

increase the cornea's mechanical stability
to stop progression of bulging and thinning of the cornea
to prevent the need for corneal transplantation

Corneal Cross Linking is performed by

Applying Riboflavin (Vitamin B2) eye drops every 2 minutes for 30 minutes to the cornea
Illuminating the cornea with UV-light

This register of Corneal Cross Linking procedures performed in Germany serves to

gather long-term results
detect rare complications and side-effects
evaluate the efficacy in a large number of patients

Conditions: Keratoconus
Being tested: CCL (Corneal Cross Linking)
Keywords: keratoconus, cornea, cross linking, UV-light, riboflavin
Medical subject headings: Keratoconus, Corneal Diseases

What participants receive

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

CCL (Corneal Cross Linking)Procedure or surgery
Also called Collagen cross linking, Corneal collagen cross linking, CCL, 3C-L
Apply Riboflavin 0.1% in Dextran 500 20% in NaCl solution Illuminate with UV-light of 365 nm wave-length and 3.0 mW/cm² intensity at 5 cm distance

Study groups in NCT00560651
Study group	Role	What they receive
1		Cross linked eyes Receives: Procedure: CCL (Corneal Cross Linking)

What is being measured

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

Visual Acuity
Corrected Visual Acuity after crosslinking at the latest follow up examination
Measured: 172 to 3396 days
Postoperative K Max
K max after Crosslinking
Measured: 172 to 3396 days
Sphere
Sphere values after crosslinking at lastest-follow-up
Measured: 172 to 3396 days
Cylinder
Refractive cylinder after Crosslinking at latest follow-up
Measured: 172 to 3396 days

Timeline

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

Nov 2007Nov 2027

First posted20 Nov 2007 (estimated)
Study startNov 2007
Primary completionNov 2024
Study completionNov 2027 (estimated)

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (4)Papers the sponsor has linked to this study.
Other trials for KeratoconusStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

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

Study design

Study type: Observational
Observational model: Other
Time perspective: Prospective
Enrolment: 356 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT00560651
Sponsor's protocol ID: CCL
Status last verified: May 2026
First submitted: 19 Nov 2007
Last updated: 18 Jun 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No

Publications

Koller T, Seiler T. [Therapeutic cross-linking of the cornea using riboflavin/UVA]. Klin Monbl Augenheilkd. 2007 Sep;224(9):700-6. doi: 10.1055/s-2007-963492. German.
PubMed 17846959
Spoerl E, Mrochen M, Sliney D, Trokel S, Seiler T. Safety of UVA-riboflavin cross-linking of the cornea. Cornea. 2007 May;26(4):385-9. doi: 10.1097/ICO.0b013e3180334f78.
PubMed 17457183
Seiler T, Hafezi F. Corneal cross-linking-induced stromal demarcation line. Cornea. 2006 Oct;25(9):1057-9. doi: 10.1097/01.ico.0000225720.38748.58.
PubMed 17133053
Wollensak G, Aurich H, Pham DT, Wirbelauer C. Hydration behavior of porcine cornea crosslinked with riboflavin and ultraviolet A. J Cataract Refract Surg. 2007 Mar;33(3):516-21. doi: 10.1016/j.jcrs.2006.11.015.
PubMed 17321404

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

Not yet recruiting
Performance Evaluation of the OCUTOP Hand-held Corneal Topographer
Corneal Topography, Dry Eye Syndromes
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Proof-of-Concept for a Novel Optical Aperture Contact Lens in Presbyopia and Keratoconus
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RecruitingObservational study
A Study to Test the Diagnostic Potential of Brillouin Microscopy for Corneal Ectasia
Keratoconus, Ectasia
RecruitingObservational study
UNITY DX Cornea Study
Tomography
Enrolling by invitationObservational study
Corneal Biomechanical Analysis Using Brillouin Microscopy
Keratoconus, Keratoconus, Unstable

All Keratoconus trials

Study at a glance

From the registry record, last updated by the sponsor on 18 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: German Corneal Cross Linking Register
ClinicalTrials.gov ID: NCT00560651
Acronym / sponsor ID: CCL
Conditions: Keratoconus
Keywords: keratoconus, cornea, cross linking, UV-light, riboflavin
Study type: Observational
Recruitment status: Active, not recruiting
Enrolment: 356 participants (actual)
Lead sponsor: Suphi TaneriUniversity, hospital or other
Study start: Nov 2007 (actual)
Primary completion: Nov 2024 (actual)
Study completion: Nov 2027 (estimated)
First posted: 20 Nov 2007 (estimated)
Results: Posted 18 Jun 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Corneal Cross Linking is designed to

increase the cornea's mechanical stability
to stop progression of bulging and thinning of the cornea
to prevent the need for corneal transplantation

Corneal Cross Linking is performed by

Applying Riboflavin (Vitamin B2) eye drops every 2 minutes for 30 minutes to the cornea
Illuminating the cornea with UV-light

This register of Corneal Cross Linking procedures performed in Germany serves to

gather long-term results
detect rare complications and side-effects
evaluate the efficacy in a large number of patients

Study design

Observational model: Other
Time perspective: Prospective
Number of arms: 1

Arm	Type	Receives
1	–	Procedure: CCL (Corneal Cross Linking)Cross linked eyes

Who may qualify

Sex: All
Healthy volunteers: Not accepted
Age groups: Child, Adult, Older adult
Study population: Patients treated with Corneal Cross Linking in Germany

Key inclusion criteria (1 listed)

Patients diagnosed with keratokonus and treated with corneal cross Linking in Germany

Key exclusion criteria (1 listed)

Non-ectatic conditions

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
CCL (Corneal Cross Linking)Also: Collagen cross linking, Corneal collagen cross linking, CCL, 3C-LApply Riboflavin 0.1% in Dextran 500 20% in NaCl solution Illuminate with UV-light of 365 nm wave-length and 3.0 mW/cm² intensity at 5 cm distance	Procedure or surgery	1

Primary outcome

Visual Acuity
Time frame: 172 to 3396 days
Corrected Visual Acuity after crosslinking at the latest follow up examination
Postoperative K Max
Time frame: 172 to 3396 days
K max after Crosslinking
Sphere
Time frame: 172 to 3396 days
Sphere values after crosslinking at lastest-follow-up
Cylinder
Time frame: 172 to 3396 days
Refractive cylinder after Crosslinking at latest follow-up

Results and safety

Results posted to the registry on 18 Jun 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
PRK CXL	49	49
PTK CXL	149	149
Manual CXL	158	158

Primary outcome: Visual Acuity

Time frame: 172 to 3396 days. Geometric mean (Standard Deviation). Unit: letters read per line

Measure	PRK CXL n = 33	PTK CXL n = 70	Manual CXL n = 20
Value	0.85 (0.33)	0.83 (0.36)	0.79 (0.35)

Population analysed: Different numbers due to incomplete measurements during examination

Primary outcome: Postoperative K Max

Time frame: 172 to 3396 days. Mean (Standard Deviation). Unit: Diopters

Measure	PRK CXL n = 33	PTK CXL n = 70	Manual CXL n = 16
Value	49.37 (4.59)	49.9 (4.85)	52.36 (5.05)

Primary outcome: Sphere

Time frame: 172 to 3396 days. Mean (Standard Deviation). Unit: Diopters

Measure	PRK CXL n = 33	PTK CXL n = 70	Manual CXL n = 20
Value	0.5 (2.21)	-0.06 (2.72)	-0.87 (2.16)

Primary outcome: Cylinder

Time frame: 172 to 3396 days. Mean (Standard Deviation). Unit: Diopters

Measure	PRK CXL n = 33	PTK CXL n = 70	Manual CXL n = 20
Value	-1.5 (1.17)	-2.23 (1.92)	-2.16 (1.78)

Adverse events

Time frame: Up until 3 month post corneal crosslinking. Other adverse events reported at 5% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
PRK CXL	0 of 33 (0%)	6 of 33 (18.2%)	0 of 33
PTK CXL	0 of 70 (0%)	5 of 70 (7.1%)	0 of 70
Manual CXL	0 of 20 (0%)	0 of 20 (0%)	0 of 20

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 18 Jun 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Background: PubMed 17846959Koller T, Seiler T. [Therapeutic cross-linking of the cornea using riboflavin/UVA]. Klin Monbl Augenheilkd. 2007 Sep;224(9):700-6. doi: 10.1055/s-2007-963492. German.
Background: PubMed 17457183Spoerl E, Mrochen M, Sliney D, Trokel S, Seiler T. Safety of UVA-riboflavin cross-linking of the cornea. Cornea. 2007 May;26(4):385-9. doi: 10.1097/ICO.0b013e3180334f78.
Background: PubMed 17133053Seiler T, Hafezi F. Corneal cross-linking-induced stromal demarcation line. Cornea. 2006 Oct;25(9):1057-9. doi: 10.1097/01.ico.0000225720.38748.58.
Background: PubMed 17321404Wollensak G, Aurich H, Pham DT, Wirbelauer C. Hydration behavior of porcine cornea crosslinked with riboflavin and ultraviolet A. J Cataract Refract Surg. 2007 Mar;33(3):516-21. doi: 10.1016/j.jcrs.2006.11.015.
Click here for more information about this study: German Register of Corneal Cross LinkingLink provided by the sponsor.

Related trials for Keratoconus

Not yet recruiting
Performance Evaluation of the OCUTOP Hand-held Corneal Topographer
Corneal Topography, Dry Eye Syndromes
Recruiting
Proof-of-Concept for a Novel Optical Aperture Contact Lens in Presbyopia and Keratoconus
Keratoconus, Presbyopia
RecruitingObservational study
A Study to Test the Diagnostic Potential of Brillouin Microscopy for Corneal Ectasia
Keratoconus, Ectasia
RecruitingObservational study
UNITY DX Cornea Study
Tomography
Enrolling by invitationObservational study
Corneal Biomechanical Analysis Using Brillouin Microscopy
Keratoconus, Keratoconus, Unstable

Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Suphi Taneri, MD study chair

Augenklinik am St. Franziskus Hospital

Berthold Seitz, MD study director

University of Homburg, Saar, Germany

Philip Maier, MD study director

Univer. Freiburg, Germany

2 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

An observational study of Keratoconus, run by Suphi Taneri at 2 sites in Germany.

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 1 inclusion and 1 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 18 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 2 sites in Germany. 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.

Are results available for this study?

Yes. Results are posted in the registry (first posted 18 Jun 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

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?

Visual Acuity (time frame: 172 to 3396 days). The study lists 4 primary outcomes in all. 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 NCT00560651, 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 18 Jun 2026.