Shape variation of optic nerve head by mechanical analysis using three-dimensional finite element model / 中国组织工程研究

ABSTRACT

BACKGROUND:The measure and prediction of the shape of optic nerve head are the key issues for early diagnosis and duration prediction of glaucoma. Therefore, it is significant to research the shape variation of optic nerve head under high intraocular pressure. OBJECTIVE:To establish three-dimensional finite element model of optic nerve head and to analyze the deformation of optic nerve head and the change in retina thickness after acute high intraocular pressure. METHODS:Animal model of acute ocular hypertension was established by methods of anterior chamber perfusion. The tomographic images of the optic nerve head of a cat were obtained at the normal intraocular pressure and 5 320 Pa, 7 980 Pa, 10 640 Pa, 13 300 Pa, 15 960 Pa intraocular pressures using optical coherence tomography. Then, we measured the variation of retinal thickness at typical location. Basing on the tomographic images of optic nerve head of a cat at normal intraocular pressure, we obtained three-dimensional structure of retina and choroid using software MIMICS. Then three-dimensional model of optic nerve head was established by assembling the retina and choroid. The deformation of optic nerve head and the change in retinal thickness under high intraocular pressure were observed using software ABAQUS. The effectiveness of the model was verified by the experimental result. RESULTS AND CONCLUSION:With the increase of intraocular pressure, the retinal thickness is thinner, the optic nerve head depth, width and the ratio of the depth to width are gradual y increased. It suggests that the acute high intraocular pressure causes retinal thinning, optic nerve head widening and deepening. It is feasible to establish optic nerve head modeling in vivo by using optical coherence tomography, mechanical analysis can be applied to predict the shape variation of optic nerve head, which is significant to further deduce the pathological process of glaucoma.