title: Contact lens failure in keratoconus management.
abstract: OBJECTIVE
  Surgery is indicated for keratoconus when management with contact lenses fails. The authors sought to determine the relative contribution of various preoperative patient and ocular factors to the ultimate causes of contact lens failure.
  
  
  METHODS
  The records of unoperated eyes of keratoconus patients whose contact lenses were managed intensively before undergoing penetrating keratoplasty (PK) at the authors' institution between 1981 and 1990 were selected for study. Univariate and multivariate analyses were performed to identify risk factors for early contact lens failure.
  
  
  RESULTS
  The records of 99 keratoconic eyes of 75 patients with an average age of 34 years and average keratometry readings of 57.5 diopters at presentation were studied. Cases had been followed for an average of 27 months before PK. The primary reasons for PK were a best-corrected visual acuity of under 20/40 (despite good contact lens fit) causing disability for the patient (43%), contact lens intolerance (32%), frequent lens displacement (13%), and significant peripheral thinning of the cornea (12%). The referral source of the patient, sex, a history of PK in the fellow eye, or of contact lens wear in either eye did not alter the relative contributions of these parameters to surgery.
  
  
  CONCLUSIONS
  Poor best-corrected visual acuity at presentation, higher keratometry readings (greater than or equal to 55 D), age (greater than or equal to 40 years), and duration of disease (greater than 5 years) were significantly associated with failure due to poor functional acuity and peripheral thinning, frequently leading to surgery within the first 12 months after presentation.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois, College of Medicine, Chicago.
authors.forename: M R
authors.initials: MR
authors.lastname: Dana
authors.forename: J L
authors.initials: JL
authors.lastname: Putz
authors.forename: M A
authors.initials: MA
authors.lastname: Viana
authors.forename: J
authors.initials: J
authors.lastname: Sugar
authors.forename: T T
authors.initials: TT
authors.lastname: McMahon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003261:Contact Lenses; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000601:surgery / Q000628:therapy*; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011475:Prosthesis Failure; D012189:Retrospective Studies; D012307:Risk Factors; D014786:Vision Disorders / Q000209:etiology; D014792:Visual Acuity