Study on establishment and mechanics application of finite element model of bovine eye

Yan-Hui Cui (1) , Ju-Fang Huang (1) , Si-Ying Cheng (2) , Wei Wei (3) , Lei Shang (1) , Na Li (4) , Kun Xiong (1)

1 Department of Anatomy and Neurobiology, Morphological Sciences
2 Eight-year clinical medicine, Xiangya Medical
3 LBA UMR T24 - Laboratoire de Biomécanique Appliquée
4 Radiology Department, Third Xiangya Hospital, Central South

Background: Glaucoma mainly induced by increased intraocular pressure (IOP), it was believed that the pressure that wall of eyeball withstands were determined by material properties of the tissue and stereoscopic geometry of the eyeball. In order to study the pressure changes in different parts of interior eyeball wall, it is necessary to develop a novel eye ball FEM with more accurate geometry and material properties. Use this model to study the stress changes in different parts of eyeball, especially the lamina cribrosa (LC) under normal physiological and pathological IOP, and provide a mathematical model for biomechanical studies of selected retinal ganglion cells (RGCs) death. Methods: (1) Sclera was cut into 3.8-mm wide, 14.5-mm long strips, and cornea was cut into 9.5-mm-wide and 10-mm-long strips; (2) 858 Mini BionixII biomechanical loading instrument was used to stretch sclera and cornea. The stretching rate for sclera was 0.3 mm/s, 3 mm/s, 30 mm/s, 300 mm/s; and for cornea were 0.3 mm/s and 30 mm/s. The deformation-stress curve was recorded; (3) Naso-temporal and longitudinal distance of LC were measured; (4) Micro-CT was used to accurately scan fresh bovine eyes and obtain the geometrical image and data to establish bovine eye model. 3-D reconstruction was performed using these images and data to work out the geometric shape of bovine eye; (5) IOP levels for eyeball FEM was set and the inner wall of eyeball was used taken as load-bearing part. Simulated eyeball FE modeling was run under the IOP level of 10 mmHg, 30 mmHg, 60 mmHg and 100 mmHg, and the force condition of different parts of eyeball was recorded under different IOP levels. Results: (1) We obtained the material parameters more in line with physiological conditions and established a more realistic eyeball model using reversed engineering of parameters optimization method to calculate the complex nonlinear super-elastic and viscoelastic parameters more accurately; (2) We observed the following phenomenon by simulating increased pressure using FEM: as simulative IOP increased, the stress concentration scope on the posterior half of sclera became narrower; in the meantime, the stress-concentration scope on the anterior half of scleral gradually expanded, and the stress on the central part of LC is highest.

Mots clés: Finite element modeling; Sclera; Lamina cribrosa; High increased intraocular pressure

Domaines: Sciences du Vivant [q-bio]; Médecine humaine et pathologie

Yan-Hui Cui, Ju-Fang Huang, Si-Ying Cheng, Wei Wei, Lei Shang, et al.. Study on establishment and mechanics application of finite element model of bovine eye. BMC Ophthalmology, 2015, pp.1-16. ⟨10.1186/s12886-015-0073-4⟩. ⟨hal-01198621⟩