On the Spatiotemporal Material Anisotropy of the Vitreous Body in Tension and Compression

Abstract

Although linked to several vitreoretinal pathologies including traumatic retinal tears, breaks, and symptomatic vitreomacular traction, the dynamic material behavior of the vitreous body in response to mechanical loads is not well understood. The purpose of this study was to evaluate spatiotemporal patterns of collagen fiber reorganization and vitreous deformation (strain) in response to tensile and compressive forces. Using thick slabs of bovine eyes we examined collagen fiber reorganization following tensile and compressive step-loading with quantitative polarized light imaging. Strains were measured from sparse marker arrays and temporal collagen behavior was estimated from creep compliance rheological tests. Results showed that under applied loads (1) collagen fibers became significantly more aligned at the vitreous base (near the pars plana and the ciliary body), (2) vitreous located directly behind the lens deformed significantly more than surrounding regions, and (3) changes in collagen fiber alignment occurred on a short (<5 s) timescale. Together these results show that, despite a homogeneous visual appearance, the vitreous body exhibits anisotropic material behavior in tension and compression. Spatiotemporal patterns of collagen rearrangement were consistent with epidemiological patterns of traumatic retinal damage and vitreoretinal topology. High strains in the vitreous corresponded with locations of lower collagen content that are prone to age-related degeneration. These data suggest that differential fiber alignment and mechanical deformation could contribute to the pathogenesis of these diseases. Computational models that incorporate these experimental data will help improve our understanding of the biomechanical mechanisms that contribute to the pathogenesis of traumatic retinal damage, vitreous degeneration, and vitreoretinal disease.

Motion of the vitreous humour in a deforming eye–fluid-structure interaction between a nonlinear elastic solid and viscoleastic fluid

“…Motivated by these experiments we consider the following problem. The sample is modelled as a 2 cm high cylinder, see Figure 4a, while the cylinder cross-section has the shape similar to that in the experiment by Shah et al [2], see Figure 3. The domain is composed of three parts, the vitreous humor occupies the cavity Ω X that is formed by the lens Ω 1 X and the sclera Ω 2 X , see Figure 4a.…”

“…In the experiments from Shah et al [2] fresh bovine eyes were cut in an anterior-posterior direction to create approximately 2 cm thick samples with an optically clear window to analyze the changes during the experiment, see Figure 1. Placed in an anterior-posterior orientation to the load cells the samples were attached at the sclera and near the lens by cotton swabs fixed via clamps to the load cells, Figure 1.…”

“…Boundary conditions. Concerning the boundary conditions, we prescribe boundary conditions that again resemble the experimental setting by Shah et al [2]. The bottom base of the cylinder Γ bottom that is placed at z = 0, see Figure 4b, is assumed to be immovable in the direction of the z-axis, hence the z component of the displacement vector u is fixed to zero.…”

“…We present a numerical methodology that is capable of handling the fluid-structure interaction problem. Then we apply the methodology in numerically solving the governing equations in a setting that resembles the recent experiment by Shah et al [2]. The numerical experiment shows that the adopted methodology can be used to predict key mechanical quantities such as the mechanical stress at the interface between the vitreous humour and the retina.…”

Study On the Effectiveness and Safety of Foldable Capsular Vitreous Body Implantation

“…Natural vitreous body, which was proved to maintain a certain spatial relationship with dipolar water molecules, has the ability to support the retina, supply nutrition, stabilize intraocular metabolism, act as cell barrier and ocular refractive media, etc [1] . However, the composition of natural vitreous body is unclear, which means it is impossible to create artificial vitreous body [2][3][4] . Furthermore, due to the natural vitreous body is non-renewable [5][6][7] , vitrectomy and SO tamponade are required when vitreoretinal diseases occur, such as retinal detachment caused by severe ocular trauma, post-trauma proliferative vitreoretinopathy, proliferative diabetic retinopathy and endophthalmitis [8][9][10][11] .…”