KeratoconusNCT03923101
The Homburg Keratoconus Center (HKC)
An observational study of Keratoconus, run by Universität des Saarlandes at 1 site in Germany.
Trial summary
Aim of this study is to conduct longitudinal and cross-sectional analyses about the corneal ectatic disease Keratoconus based on data obtained from Keratoconus patients in the Homburg Keratoconus Center (HKC). Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Keratoconus
- What is being tested?
- Topographic, tomographic and biomechanical analysis.
- How many people
- 5,000 participants
- Where
- 1 siteGermany
- Study dates
- 1 Jan 2011to 1 Jan 2036
- How long will I take part?
- 10 Years
- Phase
- Observational
- 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 Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: Keratoconus patients of all ages presenting in the department of ophthalmology, Saarland University Medical Center, Homburg, Saarland, Germany, should be included.
Who may be able to join
- All Keratoconus patients presenting in the department of ophthalmology, Saarland University Medical Center, Homburg, Saarland, Germany.
Who cannot join
- Patients without Keratoconus.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Germany1 site, 1 recruiting
- Recruiting
Department of Ophthalmology
Homburg, Saarland, 66421
Elias Flockerzi, PD Dr.med., 0049-6841-16-22302, elias.flockerzi@uks.eu
Berthold Seitz, Prof.Dr.med., 0049-6841-16-22387, berthold.seitz@uks.eu
About this study
Official title: The Homburg Keratoconus Center (HKC) - a Keratoconus Observation Study
Aim of this study is to conduct longitudinal and cross-sectional analyses about the corneal ectatic disease Keratoconus based on data obtained from Keratoconus patients in the Homburg Keratoconus Center (HKC).
The Homburg Keratoconus Center (HKC) was founded in 2010 and, up to now, comprises more than 3,000 Keratoconus patients. Topographic, tomographic and biomechanic characteristics of the disease are being analyzed with the intention to elucidate how the disease begins and develops during lifetime.
- Conditions
- Keratoconus
- Being tested
- Topographic, tomographic and biomechanical analysis.
- Keywords
- Keratoconus, Crosslinking, Intracorneal ring segments, Gas-permeable rigid contact-lenses, Penetrating Keratoplasty, Deep anterior lamellar Keratoplasty, ABCD Grading System
- Medical subject headings
- Keratoconus
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Topographic, tomographic and biomechanical analysis.Diagnostic test
The study is based upon data obtained during routine medical follow-ups using
- the Pentacam high resolution (Oculus, Wetzlar, Germany)
- the Corvis ST (Oculus, Wetzlar, Germany)
- the Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2 (Tomey, Nagoya, Japan)
- the Ocular Response Analyzer (Reichert Technologies, New York, USA).
| Study group | Role | What they receive |
|---|---|---|
| Patients with Keratoconus | Aim is to include as many Keratoconus patients as possible with the intention to elucidate how the disease begins and develops during lifetime. Receives: Diagnostic Test: Topographic, tomographic and biomechanical analysis. |
What is being measured
The primary outcome is the main question the study is designed to answer.
An overview about development of anterior corneal curvature in Keratoconus disease during lifetime.
The anterior radius of curvature (ARC, 3mm zone) of Keratoconus patients as measured by the Pentacam high resolution (Oculus, Wetzlar, Germany) at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
Measured: 01/01/2011-01/01/2019
An overview about development of posterior corneal curvature in Keratoconus disease during lifetime.
The posterior radius of curvature (PRC, 3mm zone) of Keratoconus patients as measured by the Pentacam high resolution (Oculus, Wetzlar, Germany) at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
Measured: 01/01/2011-01/01/2019
An overview about development of the thinnest corneal pachymetry in Keratoconus disease during lifetime.
The thinnest corneal pachymetry of Keratoconus patients as measured by the Pentacam high resolution (Oculus, Wetzlar, Germany) at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
Measured: 01/01/2011-01/01/2019
An overview about development of the best corrected distance visual acuity in Keratoconus disease during lifetime.
The best corrected distance visual acuity of Keratoconus patients as raised as part of the clinical examination at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
Measured: 01/01/2011-01/01/2019
Reproducibility study: Kmax.
Measurements of Kmax measured by different devices (Pentacam high resolution, Oculus, Wetzlar, Germany; Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2, Tomey, Nagoya, Japan) are being compared and set into relation at different Keratoconus stages with the intention to investigate, whether measurement inaccuracies occur at later Keratoconus stages using different devices.
Measured: 01/01/2011-01/01/2019
Reproducibility study: Thinnest corneal pachymetry.
Measurements of the thinnest corneal pachymetry as measured by different devices (Pentacam high resolution, Oculus, Wetzlar, Germany; Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2, Tomey, Nagoya, Japan) are being compared and set into relation at different Keratoconus stages with the intention to investigate, whether measurement inaccuracies occur at later Keratoconus stages using different devices.
Measured: 01/01/2011-01/01/2019
Reproducibility study: Thinnest corneal pachymetry at the apex position.
Measurements of the thinnest corneal pachymetry at the apex position as measured by different devices (Pentacam high resolution, Oculus, Wetzlar, Germany; Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2, Tomey, Nagoya, Japan) are being compared and set into relation at different Keratoconus stages with the intention to investigate, whether measurement inaccuracies occur at later Keratoconus stages using different devices.
Measured: 01/01/2011-01/01/2019
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Apr 2019
- Study start1 Jan 2011
- Primary completion1 Jan 2036 (estimated)
- Study completion1 Jan 2036 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (9)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
- Cohort
- Time perspective
- Other
- Enrolment
- 5,000 participants (estimated)
- Target duration
- 10 Years
Sponsor and investigators
- Lead sponsor
- Universität des Saarlandes
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Elias Flockerzi, University Hospital, Saarland
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03923101
- Sponsor's protocol ID
- HKC
- Status last verified
- Apr 2026
- First submitted
- 22 Mar 2019
- Last updated
- 27 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Flockerzi E, Seitz B. Keratectasia severity staging and progression assessment based on the biomechanical E-staging. Eye Vis (Lond). 2024 Jul 1;11(1):24. doi: 10.1186/s40662-024-00392-3.
PubMed 38946004Sideroudi H, Flockerzi E, Daas L, Jullien T, Xanthopoulou K, Hamon L, Seitz B. Baseline Characteristics of 1976 Patients With Ectatic Corneal Disorders at a Single Center From 2010 to 2021: A Cross-Sectional Study of the Homburg Keratoconus Center. Eye Contact Lens. 2023 Sep 1;49(9):392-398. doi: 10.1097/ICL.0000000000001014. Epub 2023 Jul 14.
PubMed 37458424Flockerzi E, Vinciguerra R, Belin MW, Vinciguerra P, Ambrosio R Jr, Seitz B. Combined biomechanical and tomographic keratoconus staging: Adding a biomechanical parameter to the ABCD keratoconus staging system. Acta Ophthalmol. 2022 Aug;100(5):e1135-e1142. doi: 10.1111/aos.15044. Epub 2021 Oct 16.
PubMed 34655452Flockerzi E, Elzer B, Daas L, Xanthopoulou K, Eppig T, Langenbucher A, Seitz B. The Reliability of Successive Scheimpflug Imaging and Anterior Segment Optical Coherence Tomography Measurements Decreases With Increasing Keratoconus Severity. Cornea. 2021 Nov 1;40(11):1433-1439. doi: 10.1097/ICO.0000000000002657.
PubMed 34633357Flockerzi E, Vinciguerra R, Belin MW, Vinciguerra P, Ambrosio R Jr, Seitz B. Correlation of the Corvis Biomechanical Factor with tomographic parameters in keratoconus. J Cataract Refract Surg. 2022 Feb 1;48(2):215-221. doi: 10.1097/j.jcrs.0000000000000740.
PubMed 34321407Flockerzi E, Hafner L, Xanthopoulou K, Daas L, Munteanu C, Langenbucher A, Seitz B. Reliability analysis of successive Corneal Visualization Scheimpflug Technology measurements in different keratoconus stages. Acta Ophthalmol. 2022 Feb;100(1):e83-e90. doi: 10.1111/aos.14857. Epub 2021 Mar 22.
PubMed 33750037Flockerzi E, Xanthopoulou K, Goebels SC, Zemova E, Razafimino S, Hamon L, Jullien T, Kluhspies U, Eppig T, Langenbucher A, Seitz B. Keratoconus staging by decades: a baseline ABCD classification of 1000 patients in the Homburg Keratoconus Center. Br J Ophthalmol. 2021 Aug;105(8):1069-1075. doi: 10.1136/bjophthalmol-2020-316789. Epub 2020 Aug 23.
PubMed 32830125Flockerzi E, Berger T, Seitz B, Hamon L, Daas L. Evaluation of dynamic corneal response parameters and the biomechanical E-staging after Intacs(R) SK implantation in keratoconus. Indian J Ophthalmol. 2024 May 1;72(Suppl 3):S495-S500. doi: 10.4103/IJO.IJO_2944_23. Epub 2024 Apr 20.
PubMed 38648457Flockerzi E, Xanthopoulou K, Daas L, Feld S, Langenbucher A, Seitz B. Evaluation of Dynamic Corneal Response Parameters and the Biomechanical E-Staging After Accelerated Corneal Cross-Linking in Keratoconus. Asia Pac J Ophthalmol (Phila). 2022 Nov 1;11(6):514-520. doi: 10.1097/APO.0000000000000580.
PubMed 36417675
Study at a glance
From the registry record, last updated by the sponsor on 27 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Homburg Keratoconus Center (HKC) - a Keratoconus Observation Study
- ClinicalTrials.gov ID
- NCT03923101
- Acronym / sponsor ID
- HKC
- Conditions
- Keratoconus
- Keywords
- Keratoconus, Crosslinking, Intracorneal ring segments, Gas-permeable rigid contact-lenses, Penetrating Keratoplasty, Deep anterior lamellar Keratoplasty, ABCD Grading System
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 5,000 participants (estimated)
- Lead sponsor
- Universität des SaarlandesUniversity, hospital or other
- Study start
- 1 Jan 2011 (actual)
- Primary completion
- 1 Jan 2036 (estimated)
- Study completion
- 1 Jan 2036 (estimated)
- First posted
- 22 Apr 2019 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Aim of this study is to conduct longitudinal and cross-sectional analyses about the corneal ectatic disease Keratoconus based on data obtained from Keratoconus patients in the Homburg Keratoconus Center (HKC).
The Homburg Keratoconus Center (HKC) was founded in 2010 and, up to now, comprises more than 3,000 Keratoconus patients. Topographic, tomographic and biomechanic characteristics of the disease are being analyzed with the intention to elucidate how the disease begins and develops during lifetime.
Study design
- Observational model
- Cohort
- Time perspective
- Other
- Target follow-up
- 10 Years
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Patients with Keratoconus | – | Diagnostic Test: Topographic, tomographic and biomechanical analysis.Aim is to include as many Keratoconus patients as possible with the intention to elucidate how the disease begins and develops during lifetime. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Keratoconus patients of all ages presenting in the department of ophthalmology, Saarland University Medical Center, Homburg, Saarland, Germany, should be included.
Key inclusion criteria (1 listed)
- All Keratoconus patients presenting in the department of ophthalmology, Saarland University Medical Center, Homburg, Saarland, Germany.
Key exclusion criteria (1 listed)
- Patients without Keratoconus.
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 |
|---|---|---|
| Topographic, tomographic and biomechanical analysis.The study is based upon data obtained during routine medical follow-ups using 1. the Pentacam high resolution (Oculus, Wetzlar, Germany) 2. the Corvis ST (Oculus, Wetzlar, Germany) 3. the Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2 (Tomey, Nagoya, Japan) 4. the Ocular Response Analyzer (Reichert Technologies, New York, USA). | Diagnostic test | Patients with Keratoconus |
Primary outcome
An overview about development of anterior corneal curvature in Keratoconus disease during lifetime.
Time frame: 01/01/2011-01/01/2019
The anterior radius of curvature (ARC, 3mm zone) of Keratoconus patients as measured by the Pentacam high resolution (Oculus, Wetzlar, Germany) at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
An overview about development of posterior corneal curvature in Keratoconus disease during lifetime.
Time frame: 01/01/2011-01/01/2019
The posterior radius of curvature (PRC, 3mm zone) of Keratoconus patients as measured by the Pentacam high resolution (Oculus, Wetzlar, Germany) at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
An overview about development of the thinnest corneal pachymetry in Keratoconus disease during lifetime.
Time frame: 01/01/2011-01/01/2019
The thinnest corneal pachymetry of Keratoconus patients as measured by the Pentacam high resolution (Oculus, Wetzlar, Germany) at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
An overview about development of the best corrected distance visual acuity in Keratoconus disease during lifetime.
Time frame: 01/01/2011-01/01/2019
The best corrected distance visual acuity of Keratoconus patients as raised as part of the clinical examination at different ages (according to: Belin MW and Duncan JK. Keratoconus: The ABCD grading system. Klin Monbl Augenheilkd. 2016; 233(6): 701-707) is put into relation to the age of the Keratoconus patients.
Reproducibility study: Kmax.
Time frame: 01/01/2011-01/01/2019
Measurements of Kmax measured by different devices (Pentacam high resolution, Oculus, Wetzlar, Germany; Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2, Tomey, Nagoya, Japan) are being compared and set into relation at different Keratoconus stages with the intention to investigate, whether measurement inaccuracies occur at later Keratoconus stages using different devices.
Reproducibility study: Thinnest corneal pachymetry.
Time frame: 01/01/2011-01/01/2019
Measurements of the thinnest corneal pachymetry as measured by different devices (Pentacam high resolution, Oculus, Wetzlar, Germany; Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2, Tomey, Nagoya, Japan) are being compared and set into relation at different Keratoconus stages with the intention to investigate, whether measurement inaccuracies occur at later Keratoconus stages using different devices.
Reproducibility study: Thinnest corneal pachymetry at the apex position.
Time frame: 01/01/2011-01/01/2019
Measurements of the thinnest corneal pachymetry at the apex position as measured by different devices (Pentacam high resolution, Oculus, Wetzlar, Germany; Anterior-Segment Optical Coherence Tomograph (AS-OCT) Casia 2, Tomey, Nagoya, Japan) are being compared and set into relation at different Keratoconus stages with the intention to investigate, whether measurement inaccuracies occur at later Keratoconus stages using different devices.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 Apr 2026.
- Results publication: PubMed 38946004Flockerzi E, Seitz B. Keratectasia severity staging and progression assessment based on the biomechanical E-staging. Eye Vis (Lond). 2024 Jul 1;11(1):24. doi: 10.1186/s40662-024-00392-3.
- Results publication: PubMed 37458424Sideroudi H, Flockerzi E, Daas L, Jullien T, Xanthopoulou K, Hamon L, Seitz B. Baseline Characteristics of 1976 Patients With Ectatic Corneal Disorders at a Single Center From 2010 to 2021: A Cross-Sectional Study of the Homburg Keratoconus Center. Eye Contact Lens. 2023 Sep 1;49(9):392-398. doi: 10.1097/ICL.0000000000001014. Epub 2023 Jul 14.
- Results publication: PubMed 34655452Flockerzi E, Vinciguerra R, Belin MW, Vinciguerra P, Ambrosio R Jr, Seitz B. Combined biomechanical and tomographic keratoconus staging: Adding a biomechanical parameter to the ABCD keratoconus staging system. Acta Ophthalmol. 2022 Aug;100(5):e1135-e1142. doi: 10.1111/aos.15044. Epub 2021 Oct 16.
- Results publication: PubMed 34633357Flockerzi E, Elzer B, Daas L, Xanthopoulou K, Eppig T, Langenbucher A, Seitz B. The Reliability of Successive Scheimpflug Imaging and Anterior Segment Optical Coherence Tomography Measurements Decreases With Increasing Keratoconus Severity. Cornea. 2021 Nov 1;40(11):1433-1439. doi: 10.1097/ICO.0000000000002657.
- Results publication: PubMed 34321407Flockerzi E, Vinciguerra R, Belin MW, Vinciguerra P, Ambrosio R Jr, Seitz B. Correlation of the Corvis Biomechanical Factor with tomographic parameters in keratoconus. J Cataract Refract Surg. 2022 Feb 1;48(2):215-221. doi: 10.1097/j.jcrs.0000000000000740.
- Results publication: PubMed 33750037Flockerzi E, Hafner L, Xanthopoulou K, Daas L, Munteanu C, Langenbucher A, Seitz B. Reliability analysis of successive Corneal Visualization Scheimpflug Technology measurements in different keratoconus stages. Acta Ophthalmol. 2022 Feb;100(1):e83-e90. doi: 10.1111/aos.14857. Epub 2021 Mar 22.
- Results publication: PubMed 32830125Flockerzi E, Xanthopoulou K, Goebels SC, Zemova E, Razafimino S, Hamon L, Jullien T, Kluhspies U, Eppig T, Langenbucher A, Seitz B. Keratoconus staging by decades: a baseline ABCD classification of 1000 patients in the Homburg Keratoconus Center. Br J Ophthalmol. 2021 Aug;105(8):1069-1075. doi: 10.1136/bjophthalmol-2020-316789. Epub 2020 Aug 23.
- Derived from this study: PubMed 38648457Flockerzi E, Berger T, Seitz B, Hamon L, Daas L. Evaluation of dynamic corneal response parameters and the biomechanical E-staging after Intacs(R) SK implantation in keratoconus. Indian J Ophthalmol. 2024 May 1;72(Suppl 3):S495-S500. doi: 10.4103/IJO.IJO_2944_23. Epub 2024 Apr 20.
- Derived from this study: PubMed 36417675Flockerzi E, Xanthopoulou K, Daas L, Feld S, Langenbucher A, Seitz B. Evaluation of Dynamic Corneal Response Parameters and the Biomechanical E-Staging After Accelerated Corneal Cross-Linking in Keratoconus. Asia Pac J Ophthalmol (Phila). 2022 Nov 1;11(6):514-520. doi: 10.1097/APO.0000000000000580.
- Individual participant dataSharing planned: No
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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.
1 site 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 Universität des Saarlandes at 1 site 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: looking for participants now, as of the sponsor's last update on 27 Apr 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 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?
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?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
An overview about development of anterior corneal curvature in Keratoconus disease during lifetime. (time frame: 01/01/2011-01/01/2019). The study lists 7 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 NCT03923101, which also lists 9 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 27 Apr 2026.