Three-Dimensional Reconstruction and Finite Element Analysis of Rat Trabecular Meshwork Basing on Two-Photon Microscope Images
Zhang Jing, Qian Xiuqing, Zhang Haixia, Ren Lin, Liu Zhicheng#*
Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application,School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
Abstract：Glaucoma is a disease of irreversible blindness with the most risk factors of ocular hypertension that causes damage to the visual function and optic nerve. So far, clinical evidence indicates that increased intraocular pressure (IOP) is a function of elevated resistance to drainage of aqueous humor, especially the increase of outflow resistance within the trabecular meshwork (TM). Therefore, it is very important to figure out what effects of high IOP on the structures of TM and analyze the morphologic changes of TM contributing to the increase of outflow resistance in turn. In this study, animal model of acute IOP of rat was established by methods of anterior chamber perfusion. Six SD rats were divided into A, B two groups. After being killed, the left eyes of the SD rats in group B were perfused at pressure of 60 mmHg for imaging under the condition of ocular hypertension, and the other eyes was used as the control group. The tomographic sequence images of TM were obtained in the condition of normal or high IOP by using two-photon microscopy. The effects of IOP on the TM porosity based on image processing were quantitatively investigated. The three-dimensional model of TM was obtained in the normal IOP eye, and the morphological changes of TM were analyzed under different intraocular pressures by using the finite element method. The effect of high IOP on the outflow resistance of TM was analyzed by using the experiment integrated with the simulation method. In the high IOP group, the TM beams became collapsed and merged with surrounding tissues, and the damage of TM tissue near the anterior chamber is more serious. Through the analysis of finite element method, it was found out that the biggest deformation was located in the region that the porosity of TM was larger. Meanwhile, it was indicated that the greater the pressure was, the greater the damages of TM beams was. Eyes with the high IOP may cause the structural changes of TM. Fibers of TM were collapsed. The possibility of increasing outflow resistance could occur in high IOP eyes but was much smaller in normal eyes.
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