A detailed methodology to model the Non Contact Tonometry: a Fluid Structure Interaction study.

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Computational Mechanics

Background:

• Corneal mechanical properties are vital for studying pathologies and predicting refractive surgery outcomes.
• Non-contact tonometry (NCT) assesses corneal response in vivo using an air pulse, but biomarkers reflect global behavior, not intrinsic properties.
• Accurate modeling is needed to isolate corneal mechanical response, particularly using inverse finite element methods.

Purpose of the Study:

• To construct a high-fidelity finite-element model of an idealized 3D eye for in silico non-contact tonometry.
• To develop a fluid-structure interaction (FSI) simulation for virtual air-pulse application.
• To perform a sensitivity analysis on intraocular pressure (IOP) and material parameters influencing corneal deformation biomarkers.

Main Methods:

• Developed a 3D finite-element model of the eye, including cornea, limbus, sclera, lens, and humors.
• Implemented a fluid-structure interaction (FSI) simulation to model the air-pulse dynamics.
• Conducted a sensitivity analysis to assess the impact of IOP and tissue properties on corneal deformation.

Main Results:

• Accurate air pressure profile over the cornea is essential and requires FSI simulation.
• Anisotropic material properties for the cornea and considering scleral stiffness are crucial for accurate deformation.
• Modeling the fluid-like behavior of humors is necessary to account for IOP variations during the test.

Conclusions:

• The developed FSI model provides a robust tool for in silico NCT.
• This approach enables accurate simulation of corneal biomechanics, essential for understanding disease and surgical outcomes.
• The study highlights key factors for reliable in silico modeling: air pressure, tissue properties, and IOP dynamics.