Abstract:
This study investigates the optic nerve head (ONH) as a biomechanical structure, using finite element modeling (FEM) to analyze the relationship between intraocular pressure (IOP) and the resulting stress within its load-bearing connective tissues. The researchers developed 13 idealized, three-dimensional digital models of the posterior human eye, each discretized into 900 finite elements. These models systematically varied key anatomical features, including the size and shape of the scleral canal, scleral wall thickness, and the inner radius of the eye, to cover a range of human anatomies. Each element was assigned one of two isotropic material properties: a scleral (load-bearing) or axonal (non-load-bearing) modulus of elasticity. At a simulated IOP of 15 mm Hg, the models calculated the resulting stress distribution across four regions: the laminar trabeculae, laminar insertion zone, peripapillary sclera, and posterior sclera. The results demonstrated that even at this normal IOP level, the ONH tissues are subjected to substantial stress, with maximum values ranging from 6 to 122 times the applied IOP. Stress was consistently highest within the laminar trabeculae and decreased progressively in tissues further from the scleral canal. The analysis revealed that a larger or more elongated scleral canal and a thinner sclera significantly increased the magnitude of IOP-related stress. This foundational work provides strong evidence that the unique 3D geometry of an individual's ONH is a principal determinant of its mechanical environment and susceptibility to pressure-induced damage.
