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J.J. Nichols, K.J. Steger-May, T.B. Edrington, K. Zadnik, CLEK Study Group; The Relation Between Disease Asymmetry and Severity in Keratoconus . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1313.
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Purpose: Keratoconus is described as a bilateral, asymmetric, noninflammatory corneal ectasia. Our purpose is to describe the relation between disease asymmetry and severity in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study cohort. Methods: Analyses included 1,079 keratoconus patients from the CLEK Study baseline examination visit, none of whom had undergone corneal surgery in either eye. Disease asymmetry was determined by taking the difference between eyes for continuous clinical variables and by the occurrence of the outcome in neither, one or both eyes for categorical clinical variables. Disease severity was defined using the First Definite Apical Clearance Lens (FDACL) technique (a rigid contact lens to measure corneal curvature) from the worse (steeper) eye. Statistical analyses included Pearson’s correlation coefficients (continuous variables) and analysis of variance (categorical variables). Results: There were generally weak correlations when examining the relation between asymmetry and severity for low contrast habitual acuity (r = 0.12, p = 0.0003), high contrast habitual acuity (r = 0.14, p < 0.0001), low contrast best-corrected acuity (r = 0.21, p < 0.0001), and high contrast best-corrected acuity (r = 0.29, p < 0.0001). Refractive error was more moderately correlated with disease severity (r = 0.41, p < 0.0001), as were flat (r = 0.61, p < 0.0001) and steep keratometry (r = 0.54, p < 0.0001). Analyses from the categorical signs are presented in the table below. Conclusions: These analyses suggest that keratoconus patients with greater disease severity may also be more asymmetric in their disease status. Acknowledgements: The National Eye Institute/National Institutes of Health, grants EY10419, EY10069, EY10077, EY 12656, EY02687, Conforma Contact Lenses, Paragon Vision Sciences, CIBA Vision Corporation, and the Ohio Lions Eye Research Foundation. View OriginalDownload SlideView OriginalDownload Slide
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