Purchase this article with an account.
Sabine Kling, Nandor Bekesi, Carlos Dorronsoro, Susana Marcos; Finite element modeling for the dynamic biomechanical characterization of the in-vivo cornea. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3700.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Mechanical properties give important information on the health of biological tissues. Recently new non-contact imaging techniques have been proposed to measure the dynamic response of the cornea to vibration and air-puff. In this study, we built a finite element (FE) model to relate the measured geometrical deformation to the inherent corneal biomechanical parameters.
A 2D-axissymmetric viscoelastic FE-model was built including cornea, limbus, sclera and the humors. All ocular tissues were pre-loaded with the intraocular pressure (IOP) before two different simulations were performed: (1) Transient analysis of corneal deformation following an air-puff of 115 mmHg and (2) modal analysis in the range of 50-510 Hz of the corneal vibration response. The model was optimized to reproduce experimental data of human and porcine corneas. Deformation parameters and resonance modes that were most sensitive to the inherent corneal mechanical parameters were identified.
A typical indentation (Aind=0.91 mm) of a 558μm-cornea following an air-puff resulted in an elasticity modulus of 0.75 MPa for the anterior and 0.65 MPa for the posterior cornea. Increased corneal stiffness decreased the indentation by 1.88 mm/MPa. Harmonics of the fundamental corneal resonance mode (FRes=54.8 Hz) were observed at 131, 232, 328, 433 and 500 Hz shifting to higher frequencies for stiffer corneas (1.19-7.18 Hz/Pa). Within the physiologic range, corneal deformation following an air-puff depends significantly on corneal stiffness (ΔAind= 0.38 mm), thickness (ΔAind= 0.20 mm) and IOP (ΔAind= 0.23 mm), while the vibration resonance frequencies depend predominantly on corneal stiffness (ΔFRes=14.8 to 89.0 Hz) and density (ΔFRes=0 to -91.8 Hz).
Dynamic optical non-contact imaging in combination with finite element modeling will allow an in-vivo analysis of corneal biomechanical property changes in disease and after treatment. The simulations allowed retrieving inherent corneal biomechanical parameters. While IOP and geometrical parameters played a major role in the corneal deformation with air-puff, the vibration modes did not critically depend on these parameters.
This PDF is available to Subscribers Only