A new measure of disease severity in keratoconus

T. B. Edrington, J. T. Barr, K. Zadnik, M. O. Gordon

Research output: Contribution to journalArticlepeer-review


Purpose. The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study is a natural history study of keratoconus being conducted at 16 optometric and ophthalmologic clinical sites. Data collected include three methods of quantifying disease severity and progression: keratometry, videokeratography, and first definite apical clearance lens (FDACL). Methods. The FDACL rigid contact lens is the flattest lens in the standardized CLEK diagnostic lens set that first vaults the apex of the keratoconic cornea. The finding provides a measure of the sagittal height of the cone. Results. Data from the first 500 patients show FDACL's direct relationship to steep keratometric readings (Pearson Corr OD = -0.76; OS = -0.84). FDACL's test-retest reproducibility on the first 50 repeat visits was very high (lntraclass Corr OD = 0.97; OS = 0.95). Conclusions. FDACL provides a repeatable, photographically verifiable method of evaluating corneal sagittal height.

Original languageEnglish
Pages (from-to)S557
JournalInvestigative Ophthalmology and Visual Science
Issue number3
StatePublished - Feb 15 1996


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