Human lamina cribrosa insertion and age.

Purpose: To test the hypothesis that in healthy human eyes the lamina cribrosa (LC) insertion into the pia mater increases with age.

Methods: The optic nerve heads (ONHs) of donor eyes fixed at either 5 or 50 mm Hg of IOP were sectioned, stained, and imaged under bright- and dark-field conditions. A 3-dimensional (3D) model of each ONH was reconstructed.

Finite element modeling of the human sclera: influence on optic nerve head biomechanics and connections with glaucoma.

Scleral thickness, especially near the optic nerve head (ONH), is a potential factor of interest in the development of glaucomatous optic neuropathy. Large differences in the dimensions of the sclera, the principal load-bearing tissue of the eye, have been observed between individuals. This study aimed to characterize the effects of these differences on ONH biomechanics.

Biaxial mechanical testing of human sclera.

The biomechanical environment of the optic nerve head (ONH), of interest in glaucoma, is strongly affected by the biomechanical properties of sclera. However, there is a paucity of information about the variation of scleral mechanical properties within eyes and between individuals. We thus used biaxial testing to measure scleral stiffness in human eyes.

Dimensions of the human sclera: Thickness measurement and regional changes with axial length.

Scleral thickness, especially near the region of the optic nerve head (ONH), is a potential factor of interest in the development of glaucomatous optic neuropathy. Our goal was to characterize the scleral thickness distribution and other geometric features of human eyes. Eleven enucleated human globes (7 normal and 4 ostensibly glaucomatous) were imaged using high-field microMRI, providing 80 microm isotropic resolution over the whole eye.

3D morphometry of the human optic nerve head.

Human optic nerve head (ONH) anatomy is of interest in glaucoma. Our goal was to carry out a morphometric study of the human ONH based on 3D reconstructions from histologic sections. A set of 10 human ONHs (from four pairs of eyes plus two singles) were reconstructed in an iterative procedure that required the resulting geometries to satisfy a set of quality control criteria.

Modeling individual-specific human optic nerve head biomechanics. Part I: IOP-induced deformations and influence of geometry.

Glaucoma, the second most common cause of blindness worldwide, is an ocular disease characterized by progressive loss of retinal ganglion cell (RGC) axons. Biomechanical factors are thought to play a central role in RGC loss, but the specific mechanism underlying this disease remains unknown. Our goal was to characterize the biomechanical environment in the optic nerve head (ONH)--the region where RGC damage occurs--in human eyes.

Modeling individual-specific human optic nerve head biomechanics. Part II: influence of material properties.

Biomechanical factors acting within the optic nerve head (ONH) likely play a role in the loss of vision that occurs in glaucoma. In a companion paper (Sigal et al. 2008), we quantified the biomechanical environment within individual-specific ONH models reconstructed from human post mortem eyes.

Predicted extension, compression and shearing of optic nerve head tissues.

Glaucomatous optic neuropathy may be in part due to an altered biomechanical environment within the optic nerve head (ONH) produced by an elevated intraocular pressure (IOP). Previous work has characterized the magnitude of the IOP-induced deformation of ONH tissues but has not focused specifically on the mode of deformation (strain), i.e.

Reconstruction of human optic nerve heads for finite element modeling.

Purpose: Glaucoma is a common ocular disease whose pathogenesis is hypothesized to involve biomechanical damage to optic nerve tissues. Here we describe a method for the construction of patient-specific models that can be used to evaluate the biomechanical environment within the optic nerve head. We validate the method using a virtual eye, and demonstrate its use in computing optic nerve head biomechanics.

Finite element modeling of optic nerve head biomechanics.

Purpose: Biomechanical factors have been implicated in the development of glaucomatous optic neuropathy, particularly at the level of the lamina cribrosa. The goal of this study was to characterize the biomechanics of the optic nerve head using computer modeling techniques.

Methods: Several models of the optic nerve head tissues (pre- and postlaminar neural tissue, lamina cribrosa, central retinal vessel, sclera, and pia mater) were constructed.