title: Baseline findings in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study.
abstract: OBJECTIVE
  To describe the baseline findings in patients enrolled in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study.
  
  
  METHODS
  This is a longitudinal observational study of 1209 patients with keratoconus enrolled at 16 clinical centers. Its main outcome measures are corneal scarring, visual acuity, keratometry, and quality of life.
  
  
  RESULTS
  The CLEK Study patients had a mean age of 39.29+/-10.90 years with moderate to severe disease, assessed by a keratometric-based criterion (95.4% of patients had steep keratometric readings of at least 45 D) and relatively good visual acuity (77.9% had best corrected visual acuity of at least 20/40 in both eyes). Sixty-five percent of the patients wore rigid gas-permeable contact lens, and most of those (73%) reported that their lenses were comfortable. Only 13.5% of patients reported a family history of keratoconus. None reported serious systemic diseases that had been previously reported to be associated with keratoconus. Many (53%) reported a history of atopy. Fifty-three percent had corneal scarring in one or both eyes.
  
  
  CONCLUSIONS
  Baseline findings suggest that keratoconus is not associated with increased risk of connective tissue disease and that most patients in the CLEK Study sample represent mild to moderate keratoconus. Additional follow-up of at least 3 years will provide new information about the progression of keratoconus, identify factors associated with progression, and assess its impact on quality of life.
authors.affiliation: College of Optometry, The Ohio State University, Columbus 43210-1240, USA.
authors.forename: K
authors.initials: K
authors.lastname: Zadnik
authors.forename: J T
authors.initials: JT
authors.lastname: Barr
authors.forename: T B
authors.initials: TB
authors.lastname: Edrington
authors.forename: D F
authors.initials: DF
authors.lastname: Everett
authors.forename: M
authors.initials: M
authors.lastname: Jameson
authors.forename: T T
authors.initials: TT
authors.lastname: McMahon
authors.forename: J A
authors.initials: JA
authors.lastname: Shin
authors.forename: J L
authors.initials: JL
authors.lastname: Sterling
authors.forename: H
authors.initials: H
authors.lastname: Wagner
authors.forename: M O
authors.initials: MO
authors.lastname: Gordon
mesh_terms: D000328:Adult; D000368:Aged; D003261:Contact Lenses; D003315:Cornea / Q000473:pathology / Q000503:physiopathology*; D019781:Corneal Topography; D018450:Disease Progression; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012307:Risk Factors; D014792:Visual Acuity