Figure 3:

Eye-specific finite element modeling of the human posterior eye. A: The macro-architecture of the model is first defined by 3D delineation of anatomic surfaces in a 3D fluorescent reconstruction of a human posterior eye, based on serially imaging the block face of a paraffin-embedded ONH specimen at 1.5 × 1.5 μm/pixel resolution using an episcopic fluorescent microscope fitted with a 16-megapixel, monochrome CCD camera after each 1.5-μm-thickness microtome section is cut. Approximately 1200 images are precisely aligned to build a 3D reconstruction of an ONH using a laser displacement sensor that records the specimen position for each image. Once the autofluorescent images are aligned and stacked to create a volume, custom delineation software was used to slice the volume on 40 radial sagittal planes centered on the optic nerve head. Within each radial section, the anatomic surfaces were delineated using Bezier curves to define the morphology of the lamina cribrosa (LC), peripapillary sclera, and pia as shown [57]. B: 3D view of the Bezier curve delineations for the full set of 40 radial marking planes for a human eye, showing the anterior and posterior scleral surfaces (yellow and blue), scleral canal surface (green), exterior pial boundaries (light blue) and the anterior and posterior lamina cribrosa surfaces (lavender and magenta). C: 3D surfaces are then fit to the families of Bezier curves seen in (B) and the resulting eye-specific geometries of the optic nerve head and peripapillary sclera are then fit into a larger generic posterior scleral shell with anatomic shape and thickness. Finally, a parameterized, anatomic surface defining the prelaminar neural tissues, retina and choroid (gold, top) is added. These surfaces are then used to build the eye-specific, high-fidelity finite element mesh of the human posterior eye using quadratic tetrahedral elements with ten nodes.