Three-Year Follow-up of Biomechanical Changes in Very Asymmetric Ectasia

Abstract

Purpose: The purpose of this study was to assess longitudinal corneal biomechanical changes in fellow eyes with normal topography in patients with very asymmetric ectasia (VAE) for 3 years. Methods: Clinical records of 30 patients with VAE who met the inclusion criteria were retrospectively reviewed. Patients with VAE were defined as having clinical ectasia in 1 eye and normal topography in the fellow eye. Patients were subdivided into 2 groups based on baseline corneal tomography data: fellow eye with normal topography/tomography (fellow eye with NTT) and fellow eye with normal topography and not normal tomography (fellow eye with NT). Corneal biomechanical assessment with high-speed dynamic Scheimpflug-based corneal imaging was performed at baseline and each follow-up visit on each eye. Longitudinal changes in biomechanical parameters were also investigated. Linear mixed-effects models were used to evaluate changes over time in 2 groups. Results: Significant changes in the Corvis Biomechanical Index and the stress–strain index (SSI) (P = 0.023, P = 0.034, respectively) were observed during the 3-year period in fellow eye with NT group, and only SSI showed a decreasing trend over time. A significant association between the SSI and age at the initial biomechanical assessment was observed (P < 0.001). No significant changes during the 3-year period were found in any parameters in fellow eye with NTT group. Conclusions: Based on biomechanical evaluation of the cornea over a 3-year period, possible corneal softening in fellow eye of VAE having normal topography and not normal tomography was observed, highlighting the characteristics of progressive ectatic corneal disorder even in a subclinical status. Future studies with a longer follow-up period are required.