Factors associated with corneal scarring in the Collaborative LongitudinalEvaluation of Keratoconus (CLEK) Study

Purpose. The multicenter Collaborative Longitudinal Evaluation of Keratocon us (CLEK) Study is a prospective, observational study of 1,209 keratoconus patients. We report on the factors associated with corneal scarring at base line. Methods. We defined corneal scarring as scars that had been detected both by the clinician examining the patient with the slit-lamp biomicroscop e and by masked readers of corneal photographs at the CLEK Photography Read ing Center. We investigated associations between corneal scarring and patie nt variables including gender, ethnicity, a family history of keratoconus, a history of ocular trauma, eye rubbing, contact lens wear, rigid contact l ens fitting relationships, and corneal findings (such as curvature, Vogt's striae, Fleischer's ring, and central/apical staining). Multiple logistic r egression analysis using generalized estimating equations to adjust for the correlation between eyes was used for analysis. Results, The following fac tors were found to increase the odds of corneal scarring at baseline in the CLEK Study: corneal staining (odds ratios (OR) = 3.40, 95% confidence inte rval 2.53-4.59), contact lens wear (OR = 3.51, 95% confidence interval 2.27 -5.45), Fleischer's ring (OR = 1.63, 95% confidence interval 1.11-2.40), st eeper first definite apical clearance lens base curve radius (per diopter, OR = 1.29, 95% confidence interval 1.25-1.33), and age (per decade, OR = 1. 54, 95% confidence interval 1.35-1.75). Conclusions. These baseline data su ggest that corneal scarring in keratoconus is associated with corneal stain ing, contact lens wear, Fleischer's ring, a steeper cornea, and increasing age. The factors that imply added risk for corneal scarring that may be aff ected by practitioner intervention are staining of the cornea, contact lens wear, and the contact lens fitting relationship.