KeratoconusNCT00000155
The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study
An observational study of Keratoconus, run by National Eye Institute (NEI) at 14 sites in United States.
Trial summary
To describe the clinical course of keratoconus and to describe the relationships among its visual and physiological manifestations, including high- and low-contrast visual acuity, corneal curvature, slit lamp biomicroscopic findings, corneal scarring, and quality of life. Read more about this study
- Who is it for?
- Ages 12 years and older
- Conditions the study is for
- Keratoconus
- How many people
- Not given
- Where
- 14 sitesUnited States
- Study dates
- Jun 1995to not given
- Phase
- Observational
- Are there results?
- None posted in the registry
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 12 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Patients with keratoconus were eligible if they were at least 12 years old; had an irregular cornea as determined by keratometry, retinoscopy, or direct ophthalmoscopy in at least one eye; had Vogt's striae, Fleischer's ring, or corneal scarring characteristic of keratoconus in at least one eye; and planned to stay in the area for at least 3 years. They were ineligible if they had bilateral corneal transplants or bilateral nonkeratoconic eye disease (cataract, intraocular lenses, macular disease, or optic nerve disease other than glaucoma).
Trial locations and contacts
14 sites in 1 country.
14 sites in 1 country
United States14 sites
University of California, Berkeley, School of Optometry
Berkeley, California, 94720-2020
Indiana University, School of Optometry
Bloomington, Indiana, 47405-3680
University of Illinois at Chicago, Department of Ophthalmology and Visual Sciences
Chicago, Illinois, 60612
University Hospitals of Cleveland, Department of Ophthalmology
Cleveland, Ohio, 44106
The Ohio State University, College of Optometry
Columbus, Ohio, 43210-1240
Nova Southeastern University, Health Professions Division, College of Optometry
Fort Lauderdale, Florida, 33328
Southern California College of Optometry
Fullerton, California, 92831
Gundersen Lutheran
La Crosse, Wisconsin, 54601
Jules Stein Eye Institute, University of California at Los Angeles
Los Angeles, California, 90095-7003
SUNY State College of Optometry
New York, New York, 10036-8003
Pennsylvania College of Optometry, The Eye Institute
Philadelphia, Pennsylvania, 19141
University of Utah, John Moran Eye Center
Salt Lake City, Utah, 84132
Northeastern Eye Institute
Scranton, Pennsylvania, 18503
University of Missouri-St. Louis, School of Optometry
St Louis, Missouri, 63121
About this study
To describe the clinical course of keratoconus and to describe the relationships among its visual and physiological manifestations, including high- and low-contrast visual acuity, corneal curvature, slit lamp biomicroscopic findings, corneal scarring, and quality of life.
To identify risk factors and protective factors that influence the severity and progression of keratoconus.
Read the detailed description
Keratoconus is a bilateral, asymmetric, chronic, progressive ectasia of the cornea characterized by steepening and distortion of the cornea, thinning of the apical cornea, corneal scarring, and treatment-related sequelae, such as abrasions from contact lenses and surgical complications. Patients experience distorted vision that worsens with disease progression. Their vision is typically corrected with spectacles early in the disease and, later, with rigid contact lenses. Some patients eventually undergo corneal transplantation in one or both eyes. Keratoconus affects people in their prime earning years and profoundly affects their lives.
Previous large-scale studies of keratoconus have focused on incidence and prevalence, etiologies, or the clinical management of keratoconus. Few have characterized the course of the disease and risk factors for its progression in large samples of keratoconus patients. The incidence of vision-threatening corneal scarring in keratoconus is unknown. Patient's most frequent questions--how rapidly their keratoconus will progress, how bad their vision will become, whether they will need corneal surgery, how successful their contact lenses will be--cannot be answered on the basis of the current body of knowledge.
The need for a prospective, observational study of keratoconus patients is great. Results from this study will address keratoconus patient's unanswered questions and will enable eye care practitioners to manage this complex ocular disease better.
The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study is a multicenter, observational study of 1,209 keratoconus patients followed for 3 years.
Patients are examined annually. Study measures include visual acuity, patient-reported quality of life, manifest refraction, keratometry, photodocumentation of the cornea to identify central corneal scarring, photodocumentation of the flattest contact lens that just clears the cornea, slit lamp biomicroscopy, and corneal topography. In rigid contact lens wearers, the fluorescein pattern of the patient's habitual contact lenses is photodocumented.
Patients are examined at 15 clinical centers. The clinical centers enrolled 1,209 patients in 12 months.
- Conditions
- Keratoconus
- Medical subject headings
- Keratoconus
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Sep 1999 (estimated)
- Study startJun 1995
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- 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
- Time perspective
- Prospective
Sponsor and investigators
- Lead sponsor
- National Eye Institute (NEI)
- Sponsor type
- US National Institutes of Health
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00000155
- Sponsor's protocol ID
- NEI-57
- Status last verified
- Nov 2001
- First submitted
- 23 Sep 1999
- Last updated
- 24 Jun 2005
- Results posted
- No
Publications
Barr JT, Gordon MO, Zadnik K, Pellican K, Edrington TB. Photodocumentation of corneal scarring. Collaborative Longitudinal Evaluation of Keratoconus Study Group. J Refract Surg. 1996 May-Jun;12(4):492-500. doi: 10.3928/1081-597X-19960501-13.
PubMed 8771545Edrington TB, Barr JT, Zadnik K, Davis LJ, Gundel RE, Libassi DP, McMahon TT, Gordon MO. Standardized rigid contact lens fitting protocol for keratoconus. Optom Vis Sci. 1996 Jun;73(6):369-75. doi: 10.1097/00006324-199606000-00003.
PubMed 8807647Gundel RE, Libassi DP, Zadnik K, Barr JT, Davis L, McMahon TT, Edrington TB, Gordon MO. Feasibility of fitting contact lenses with apical clearance in keratoconus. Optom Vis Sci. 1996 Dec;73(12):729-32. doi: 10.1097/00006324-199612000-00002.
PubMed 9002088Zadnik K, Barr JT, Gordon MO, Edrington TB. Biomicroscopic signs and disease severity in keratoconus. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group. Cornea. 1996 Mar;15(2):139-46. doi: 10.1097/00003226-199603000-00006.
PubMed 8925661
Study at a glance
From the registry record, last updated by the sponsor on 24 Jun 2005. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study
- ClinicalTrials.gov ID
- NCT00000155
- Acronym / sponsor ID
- NEI-57
- Conditions
- Keratoconus
- Study type
- Observational
- Recruitment status
- Unknown status
- Lead sponsor
- National Eye Institute (NEI)US National Institutes of Health
- Study start
- Jun 1995
- First posted
- 24 Sep 1999 (estimated)
- 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.
To describe the clinical course of keratoconus and to describe the relationships among its visual and physiological manifestations, including high- and low-contrast visual acuity, corneal curvature, slit lamp biomicroscopic findings, corneal scarring, and quality of life.
To identify risk factors and protective factors that influence the severity and progression of keratoconus.
Detailed description
Keratoconus is a bilateral, asymmetric, chronic, progressive ectasia of the cornea characterized by steepening and distortion of the cornea, thinning of the apical cornea, corneal scarring, and treatment-related sequelae, such as abrasions from contact lenses and surgical complications. Patients experience distorted vision that worsens with disease progression. Their vision is typically corrected with spectacles early in the disease and, later, with rigid contact lenses. Some patients eventually undergo corneal transplantation in one or both eyes. Keratoconus affects people in their prime earning years and profoundly affects their lives.
Previous large-scale studies of keratoconus have focused on incidence and prevalence, etiologies, or the clinical management of keratoconus. Few have characterized the course of the disease and risk factors for its progression in large samples of keratoconus patients. The incidence of vision-threatening corneal scarring in keratoconus is unknown. Patient's most frequent questions--how rapidly their keratoconus will progress, how bad their vision will become, whether they will need corneal surgery, how successful their contact lenses will be--cannot be answered on the basis of the current body of knowledge.
The need for a prospective, observational study of keratoconus patients is great. Results from this study will address keratoconus patient's unanswered questions and will enable eye care practitioners to manage this complex ocular disease better.
The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study is a multicenter, observational study of 1,209 keratoconus patients followed for 3 years.
Patients are examined annually. Study measures include visual acuity, patient-reported quality of life, manifest refraction, keratometry, photodocumentation of the cornea to identify central corneal scarring, photodocumentation of the flattest contact lens that just clears the cornea, slit lamp biomicroscopy, and corneal topography. In rigid contact lens wearers, the fluorescein pattern of the patient's habitual contact lenses is photodocumented.
Patients are examined at 15 clinical centers. The clinical centers enrolled 1,209 patients in 12 months.
Study design
- Time perspective
- Prospective
Who may qualify
- Ages
- 12 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Not reported in the source record.
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Jun 2005.
- Background: PubMed 8771545Barr JT, Gordon MO, Zadnik K, Pellican K, Edrington TB. Photodocumentation of corneal scarring. Collaborative Longitudinal Evaluation of Keratoconus Study Group. J Refract Surg. 1996 May-Jun;12(4):492-500. doi: 10.3928/1081-597X-19960501-13.
- Background: PubMed 8807647Edrington TB, Barr JT, Zadnik K, Davis LJ, Gundel RE, Libassi DP, McMahon TT, Gordon MO. Standardized rigid contact lens fitting protocol for keratoconus. Optom Vis Sci. 1996 Jun;73(6):369-75. doi: 10.1097/00006324-199606000-00003.
- Background: PubMed 9002088Gundel RE, Libassi DP, Zadnik K, Barr JT, Davis L, McMahon TT, Edrington TB, Gordon MO. Feasibility of fitting contact lenses with apical clearance in keratoconus. Optom Vis Sci. 1996 Dec;73(12):729-32. doi: 10.1097/00006324-199612000-00002.
- Background: PubMed 8925661Zadnik K, Barr JT, Gordon MO, Edrington TB. Biomicroscopic signs and disease severity in keratoconus. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group. Cornea. 1996 Mar;15(2):139-46. doi: 10.1097/00003226-199603000-00006.
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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. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
14 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 National Eye Institute (NEI) at 14 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
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: status not confirmed, as of the sponsor's last update on 24 Jun 2005. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 14 sites in United States. 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?
Results are not available in the source record.
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.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT00000155, 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 24 Jun 2005.