Role of corneal biomechanical properties in applanation tonometry measurements

PURPOSE: To demonstrate the importance of material properties of the cornea in intraocular pressure (IOP) readings via standard Goldmann applanation tonometry. METHODS: A realistic finite element model of the cornea was developed for the simulation of Goldmann applanation tonometry. A virtual cornea population was generated by randomly sampling material properties, central corneal thickness (CCT), and IOP for comparison with 181 clinical cases. The effect of material properties and CCT on IOP prediction in the virtual population was determined via computational simulation. RESULTS: The results show that corneal biomechanical properties (as characterized in this study by the stiffness parameter E_init) are as important as the CCT in influencing measured (Goldmann) IOP. CONCLUSIONS: This study supports the contention that the observed large scatter in standard correlations of clinical measurements of IOP versus CCT can be largely accounted for by plausible individual variations in corneal biomechanical stiffness properties.