A multivariate analysis and statistical model for predicting visual acuity and keratometry one year after crosslinking for keratoconus – Accepted Manuscript

Abstract: Purpose: To investigate putative prognostic factors for predicting visual acuity and keratometry one 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 one academic treatment centre, with minimal one-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≤0.20) 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 (ß-coefficient 0.709, P 0.02), whereas age, gender and baseline keratometry were not independent contributors. Post-treatment visual acuity could be predicted based on pre-treatment visual acuity (ß-coefficient -0.621, P <0.01, R2 0.45). Specifically, a low visual acuity predicts visual improvement. A prediction model for Kmax did not accurately estimate treatment outcomes (R2 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 pre-treatment VA. Age, gender and Kmax are debated as independent factors for predicting the outcome of treating keratoconus with CXL.