School of Engineering and Information Technology, University of New South Wales Canberra, ACT, Australia.
School of Engineering and Information Technology, University of New South Wales Canberra, ACT, Australia.
J Biomech. 2014 Jul 18;47(10):2292-9. doi: 10.1016/j.jbiomech.2014.04.040. Epub 2014 May 2.
The precise mechanism of bitemporal hemianopia (a type of partial visual field defect) is still not clear. Previous work has investigated this problem by studying the biomechanics of chiasmal compression caused by a pituitary tumour growing up from below the optic chiasm. A multi-scale analysis was performed using finite element models to examine both the macro-scale behaviour of the chiasm and the micro-scale interactions of the nerve fibres within it using representative volume elements. Possible effects of large deflection and non-linear material properties were incorporated. Strain distributions in the optic chiasm and optic nerve fibres were obtained from these models. The results of the chiasmal model agreed well with the limited experimental results available, indicating that the finite element modelling can be a useful tool for analysing chiasmal compression. Simulation results showed that the strain distribution in nasal (crossed) nerve fibres was much more nonuniform and locally higher than in temporal (uncrossed) nerve fibres. This strain difference between nasal and temporal nerve fibres may account for the phenomenon of bitemporal hemianopia.
双眼颞侧偏盲（一种部分视野缺损）的确切机制尚不清楚。之前的研究通过研究由垂体瘤从视交叉下方生长引起的视交叉压缩的生物力学来解决这个问题。使用有限元模型进行了多尺度分析，以使用代表性体积元素检查视交叉的宏观行为和其中神经纤维的微观相互作用。纳入了大挠度和非线性材料特性的可能影响。从这些模型中获得了视交叉和视神经纤维的应变分布。视交叉模型的结果与现有的有限实验结果吻合良好，表明有限元建模可以成为分析视交叉压缩的有用工具。模拟结果表明，鼻侧（交叉）神经纤维的应变分布比颞侧（未交叉）神经纤维更不均匀且局部更高。鼻侧和颞侧神经纤维之间的这种应变差异可能解释了双眼颞侧偏盲的现象。
