Non-invasive measurement of in vivo corneal steady-state biomechanical properties via controllable negative pressure inflation

Objective: To measure the steady-state corneal biomechanical properties related to postoperative corneal ectasia, keratoconus, glaucoma and other ophthalmic diseases, we propose a novel in vivo measurement method. Methods: By precisely manipulating ambient negative pressure via a suction device to achieve controlled in vivo corneal inflation, we analyzed the coupling relationship between corneal deformation response and negative pressure loading. The displacement corresponding to the corneal initial configuration under 0 mmHg was extrapolated. The inverse finite element analysis (FEA) technique was employed to calculate the segmental Young's modulus of the cornea under different steady-state intraocular pressure (IOP) conditions. Results: In vivo experiments on 3-month-old rabbit eyes demonstrated a Young's modulus of 0.2–0.3 MPa at physiological IOP (10-12 mmHg), along with an increasing trend of corneal stiffness across a pressure range of 0-85 mmHg. Conclusion: The proposed non-invasive measurement method exhibits stability and consistency in parameter inversion under different IOPs, indicating its significant clinical potential. Significance: Providing a new approach for corneal biomechanical assessment is beneficial for the diagnosis and treatment of ophthalmic diseases.