Research On Modeling And Simulation Of Virtual Chinese Human Cornea

Soft matter physics such as bio-membranes play an important creative role in basic science in the coming century. Organisms are basically composed by the soft material. Virtual organ is a very important research domain of modern biomedical engineering. The cornea is a transparent external surface, which covers the front of the eye. It is a powerful refracting matter, providing 2/3 of the eye's focusing power. So, the construction of virtual eye cornea has very important theory meaning and application value for the ophthalmological physiology, pathology, and clinic.In this paper, in order to construct form model and physical model of virtual eye cornea, the problems of image capturing, segment, analyzing, physical modeling and simulation which are involved in were discussed. And a research route that fuses the clinical data and digital human technology into the model of human eye was explored. This work is an important component of virtual Chinese human eye research.The main contents and contributions of this dissertation are as follows:a. A system which can be used to capture and analyze slit light micrograph from the ophthalmological slit lamp microscope was built. A new automatic method was proposed to analyze the micrograph of anterior eye, and some proper results were got. A method of 3D reconstruction of cornea from slit lamp images was proposed. Slit lamp microscope images were capturing with the DirectShow technology. Edges of the outside, intestine surface of the corneal and the anterior surface of the iris in the image were segmented. Some biologic parameters of anterior segment such as curvature of cornea surface, thickness of Corneal, and deepness of anterior chamber, were given automatically by curve fitting. The system can be provided as an important diagnostic tool for the doctor in the clinic. It is convenient and practicable with good intercommunion.b. One eyeball was solidified, embedded in collodion, sliced and dyed by the H.E method. 646 pieces of slice were got first time. Five datasets were established base on eye tissue slices. And images of cornea were acquired. This is the largest number of slices and the largest data of eye tissue by now. Main work was done in this process.c. A method of building a physical model of the cornea with finite element method was proposed. An individual 3D modal model of cornea was constructed. Some parameters of model were got by the slit light micrograph system. The stroma is the thickest layer and is the main load bearing parts. So the material parameter of stroma was considered in the paper. The finite element model was built up based on finite element theory. The intra-ocular pressure and external pressure were simulated, and the cornea shape changes computed using finite element analysis.d. A deformation model of virtual cornea based on mass-spring model was presented. A collision detection and response method which is adapted to surface models of cornea was proposed. The model is based on half-edge data structure and hierarchies of axis-aligned bounding boxes (AABBs) to satisfy the higher frame rates in haptic feedback. The method is simple and effective whether in theory or in practice. The experiment results show that the presented method is faster than AABBs method used solely. It creates the foundation for a virtual surgery simulation environment.