Biomicroscopic signs and disease severity in keratoconus

Karla Zadnik, Joseph T. Barr, Mae O. Gordon, Timothy B. Edrington

Research output: Contribution to journalArticlepeer-review

216 Scopus citations


The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Survey represents the largest sample of clinic-based keratoconus patients to date. Data were collected at 38 clinical centers on 1,579 keratoconus patients. This article reports demographic variables, ages, self-reported ages at diagnosis, keratometry, slit-lamp findings, systemic disease, family history of keratoconus, and best spectacle-corrected and contact lens-corrected visual acuity of this sample group. The average age of this clinic-based sample group was 37 years (range 10-89 years), with 84% between 20 and 49 years old. Thirteen percent of patients had unilateral keratoconus, defined as unilateral corneal irregularity. More advanced disease (steeper average keratometric reading) was associated with a greater likelihood of Vogt's striae, Fleischer's ring, and/or corneal scarring. Fifty-eight percent of the eyes in this group of patients had ≥20/40 visual acuity with manifest refraction. Penetrating keratoplasty was reported in 12.3% of eyes. This prospective survey identifies the association between the presence of Vogt's striae, Fleischer's ring, and/or corneal scarring and increasing steepness, as measured by keratometry.

Original languageEnglish
Pages (from-to)139-146
Number of pages8
Issue number2
StatePublished - 1996


  • Biomicroscopy
  • Cornea
  • Corneal thinning disorders
  • Irregular astigmatism
  • Keratoconus


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