Reconstruction of human optic nerve heads for finite element modeling.
OBJECTIVE
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.


METHODS
Human eyes were imaged and the optic nerve head region was processed to allow serial plastic histologic sections to be cut. These sections were photographed, unwarped and aligned so as to reconstruct three-dimensional patient-specific models incorporating sclera, pre- and post-laminar nerve, lamina cribrosa, and pia mater. Deformations, stresses and strains were computed in the resulting model using finite element techniques.


RESULTS
The approach successfully reconstructed patient-specific optic nerve head models. Reconstruction of a virtual eye showed excellent agreement between the true and reconstructed geometries, and between the deformations and strains computed on the true and reconstructed geometries. A sample reconstruction showed reasonable agreement between computed and measured retinal surface deformations.


CONCLUSIONS
The technique presented here is viable and can be used to accurately compute human optic nerve head biomechanics.
Sigal
Ian A
IA
Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada.
Flanagan
John G
JG
Tertinegg
Inka
I
Ethier
C Ross
CR
D001696:Biomechanical Phenomena; D003198:Computer Simulation; D020342:Finite Element Analysis; D005901:Glaucoma / Q000150:complications; D006801:Humans; D021621:Imaging, Three-Dimensional; D009864:Ontario; D009898:Optic Disk / Q000000981:diagnostic imaging / Q000601:surgery*; D011859:Radiography; D019651:Plastic Surgery Procedures