A Multivariate Analysis and Statistical Model for Predicting Visual Acuity and Keratometry One Year After Cross-linking for Keratoconus

PURPOSE: To investigate putative prognostic factors for predicting visual acuity and keratometry 1 year following corneal cross-linking (CXL) for treating keratoconus.

DESIGN: Prospective cohort study.

METHODS: This study included all consecutively treated keratoconus patients (102 eyes) in 1 academic treatment center, with minimal 1-year follow-up following CXL. Primary treatment outcomes were corrected distance visual acuity (logMAR CDVA) and maximum keratometry (Kmax). Univariable analyses were performed to determine correlations betWeen baseline parameters and follow-up measurements. Correlating factors (P 5.20) were then entered into a multivariable linear regression analysis, and a model for predicting CDVA and Kmax was created.

RESULTS: Atopic constitution, positive family history, and smoking were not independent factors affecting CXL outcomes. Multivariable analysis identified cone eccentricity as a major factor for predicting Kmax outcome (B coefficient = 0.709, P = .02), whereas age, sex, and baseline keratometry were not independent contributors. Posttreatment visual acuity could be predicted based on pretreatment visual acuity (B coefficient = 0.621, P <.01, Rz = 0.45). Specifically, a low visual acuity predicts visual improvement. A prediction model for Km ax did not accurately estimate treatment outcomes (R-2 = 0.15).

CONCLUSIONS: Our results confirm the role of cone eccentricity with respect to the improvement of corneal curvature following CXL. Visual acuity outcome can be predicted accurately based on pretreatment visual acuity. Age, sex, and Kmax are debated as independent factors for predicting the outcome of treating kerato. conus with CXL.