Early Biomechanical Alterations in Granular Corneal Dystrophy Type 2 From p.Ala546Asp Mutation Carriers.

Abstract

Purpose: The aim of this study was to describe corneal biomechanical changes in individuals carrying the p.Ala546Asp mutation, compare those with and without visible corneal deposits, and explore their potential relevance for early biomechanical characterization.

Methods: A case series was conducted in a Mexican mestizo family with confirmed molecular diagnosis of granular corneal dystrophy type 2 (GCD2). Participants were classified into 3 groups: mutation carriers with clinically visible corneal deposits (n = 8), mutation carriers without visible deposits (n = 3), and healthy controls without the mutation (n = 20). Corneal biomechanics were evaluated using the Corvis ST system, focusing on the corneal biomechanical index (CBI), stiffness parameter at first applanation (SP-A1), Corvis biomechanical factor (CBiF), and deformation amplitude ratio (DA ratio).

Results: CBI was significantly higher in mutation carriers, regardless of deposit presence (mutation with deposits: 0.63 ± 0.23; mutation without deposits: 0.57 ± 0.25 vs. controls: 0.11 ± 0.11, P < 0.0001). SP-A1 was significantly lower in mutation carriers, suggesting early corneal stiffness alterations. No significant differences were found between mutation carriers with and without visible deposits, indicating that biomechanical changes occur before clinical deposits form.

Conclusions: The p.Ala546Asp mutation may be associated with early corneal biomechanical instability, regardless of visible deposits. These findings suggest that biomechanical assessment may aid in the description of subclinical corneal changes in GCD2 and contribute to a better understanding of biomechanical variability among mutation carriers.