Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, 90095-7002, USA.
Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, USA.
Sci Rep. 2022 Nov 8;12(1):18985. doi: 10.1038/s41598-022-22899-2.
Tractional tethering by the optic nerve (ON) on the eye as it rotates towards the midline in adduction is a significant ocular mechanical load and has been suggested as a cause of ON damage induced by repetitive eye movements. We designed an ocular finite element model (FEM) simulating 6° incremental adduction beyond the initial configuration of 26° adduction that is the observed threshold for ON tethering. This FEM permitted sensitivity analysis of ON tethering using observed material property variations in measured hyperelasticity of the anterior, equatorial, posterior, and peripapillary sclera; and the ON and its sheath. The FEM predicted that adduction beyond the initiation of ON tethering concentrates stress and strain on the temporal side of the optic disc and peripapillary sclera, the ON sheath junction with the sclera, and retrolaminar ON neural tissue. However, some unfavorable combinations of tissue properties within the published ranges imposed higher stresses in these regions. With the least favorable combinations of tissue properties, adduction tethering was predicted to stress the ON junction and peripapillary sclera more than extreme conditions of intraocular and intracranial pressure. These simulations support the concept that ON tethering in adduction could induce mechanical stresses that might contribute to ON damage.
眼球向中线内收时视神经（ON）被牵引，这是一种显著的眼球机械负荷，被认为是重复眼球运动引起 ON 损伤的原因。我们设计了一个眼球有限元模型（FEM），模拟了 6°的内收增量，超过了 26°内收的初始配置，这是观察到的 ON 牵引的阈值。该 FEM 允许使用前、赤道、后和视盘周围巩膜以及 ON 和其鞘的测量超弹性中观察到的材料特性变化进行 ON 牵引的敏感性分析。该 FEM 预测，超过 ON 牵引起始的内收会导致视盘和视盘周围巩膜的颞侧、ON 鞘与巩膜的交界处以及视盘后层的 ON 神经组织集中受力和应变。然而，在公布的范围内，某些组织特性的不利组合会在这些区域产生更高的应力。在组织特性的最不利组合下，内收牵引被预测会对视盘交界处和视盘周围巩膜造成比眼内和颅内压极端情况更大的应力。这些模拟支持了这样一种观点，即内收时的 ON 牵引可能会引起机械应力，这些应力可能导致 ON 损伤。
