Suspended

Longitudinal Evaluation of Keratoconus Progression and Patient Quality of Life

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What is being collected

Data Collection

Collected from today forward - Prospective
Who is being recruted

Corneal Diseases

+ Eye Diseases

+ Keratoconus

Over 12 Years
See all eligibility criteria
How is the trial designed

Observational
Study Start: June 1995
See protocol details

Summary

Principal SponsorNational Eye Institute (NEI)
Last updated: January 27, 2026
Sourced from a government-validated database.Claim as a partner

Study start date: June 1, 1995

Actual date on which the first participant was enrolled.

Keratoconus is a condition that affects the cornea, the clear front part of the eye. It causes the cornea to thin and bulge out, leading to distorted vision. People with keratoconus often need glasses or rigid contact lenses to see clearly, and some may even require a corneal transplant. The condition typically affects individuals during their prime earning years and significantly impacts their lives. The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study aims to better understand how this disease progresses and what factors might influence its severity. By doing so, it hopes to provide answers to common patient questions and improve the overall management of this complex eye condition. The CLEK Study is observing 1,209 patients with keratoconus over a period of 3 years. Participants undergo annual examinations at 15 different clinical centers. These check-ups include tests to measure visual acuity, assess the quality of life, capture images of the cornea, examine the fit of contact lenses, and evaluate the overall health of the eye. The study does not involve any treatment, but rather collects information to better understand the disease. The findings from this study will help eye care practitioners manage keratoconus more effectively and provide patients with a clearer understanding of what to expect from their condition.

Official TitleThe Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study
Principal SponsorNational Eye Institute (NEI)
Last updated: January 27, 2026
Sourced from a government-validated database.Claim as a partner

Protocol

This section provides details of the study plan, including how the study is designed and what the study is measuring.

Eligibility

Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.
Conditions
Criteria

Any sex

Biological sex of participants that are eligible to enroll.

Over 12 Years

Range of ages for which participants are eligible to join.

Healthy volunteers not allowed

If individuals who are healthy and do not have the condition being studied can participate.

Conditions

Pathology

Corneal DiseasesEye DiseasesKeratoconus

Criteria

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).

Study Centers

These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.

This study has 14 locations

Suspended

University of California, Berkeley, School of Optometry

Berkeley, United StatesOpen University of California, Berkeley, School of Optometry in Google Maps
Suspended

Southern California College of Optometry

Fullerton, United States
Suspended

Jules Stein Eye Institute, University of California at Los Angeles

Los Angeles, United States
Suspended

Nova Southeastern University, Health Professions Division, College of Optometry

Fort Lauderdale, United States
Suspended14 Study Centers