Basinger B C, Rowley A P, Chen K, Humayun M S, Weiland J D
Department of Biomedical Engineering, University of Southern California, Los Angeles, 90033, USA.
J Neural Eng. 2009 Oct;6(5):055006. doi: 10.1088/1741-2560/6/5/055006. Epub 2009 Sep 1.
Epiretinal prostheses used to treat degenerative retina diseases apply stimulus via an electrode array fixed to the ganglion cell side of the retina. Mechanical pressure applied by these arrays to the retina, both during initial insertion and throughout chronic use, could cause sufficient retinal damage to reduce the device's effectiveness. In order to understand and minimize potential mechanical damage, we have used finite element analysis to model mechanical interactions between an electrode array and the retina in both acute and chronic loading configurations. Modeling indicates that an acute tacking force distributes stress primarily underneath the tack site and heel edge of the array, while more moderate chronic stresses are distributed more evenly underneath the array. Retinal damage in a canine model chronically implanted with a similar array occurred in correlating locations, and model predictions correlate well with benchtop eyewall compression tests. This model provides retinal prosthesis researchers with a tool to optimize the mechanical electrode array design, but the techniques used here represent a unique effort to combine a modifiable device and soft biological tissues in the same model and those techniques could be extended to other devices that come into mechanical contact with soft neural tissues.
用于治疗视网膜退行性疾病的视网膜假体通过固定在视网膜神经节细胞一侧的电极阵列施加刺激。这些阵列在初始植入过程中和长期使用过程中对视网膜施加的机械压力，可能会造成足够的视网膜损伤，从而降低设备的有效性。为了理解并尽量减少潜在的机械损伤，我们使用有限元分析对电极阵列与视网膜在急性和慢性加载配置下的机械相互作用进行建模。建模表明，急性固定力主要将应力分布在阵列的固定部位下方和后跟边缘，而更为适度的慢性应力则在阵列下方分布得更为均匀。在长期植入类似阵列的犬类模型中，视网膜损伤发生在相关位置，并且模型预测与台式眼壁压缩测试结果高度相关。该模型为视网膜假体研究人员提供了一种优化机械电极阵列设计的工具，但这里使用的技术代表了在同一模型中结合可修改设备和柔软生物组织的独特尝试，并且这些技术可以扩展到与柔软神经组织发生机械接触的其他设备。
