Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States.
Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Atlanta, Georgia, United States.
Invest Ophthalmol Vis Sci. 2018 Aug 1;59(10):4172-4181. doi: 10.1167/iovs.18-24463.
Choroid geometry and swelling have been proposed to contribute to ocular pathologies. Thus, it is important to understand how the choroid may impact the optic nerve head (ONH) biomechanical environment. We developed a finite element model to study how acute choroidal swelling and choroid geometry affect ONH deformation.
We developed two geometric models of the ONH: one with a "blunt" choroidal insertion and another with a "tapered" choroid insertion. We examined how choroidal volume changes (2.1-14.2 μL, estimated to occur during the ocular pulse) impact biomechanical strain in three tissue regions: the prelaminar neural tissue, lamina cribrosa, and retrolaminar neural tissue. Then, we performed a sensitivity analysis to understand how variation in ONH pressures, tissue material properties, and choroidal swelling influenced the peak tissue strains.
Choroidal swelling in the blunt choroid geometry had a large impact on the strains in the prelaminar neural tissue, with magnitudes comparable to those expected to occur due to an IOP of 30 mm Hg. Choroidal swelling in the tapered choroid geometry also affected strains but to a lesser extent compared to the blunt geometry. A sensitivity analysis confirmed that choroidal swelling was more influential on prelaminar neural tissue strains in the blunt choroid geometry.
Choroid anatomy and swelling can interact to play an important role in prelaminar neural tissue deformation. These findings suggest that the choroid may play an important, and previously unappreciated, role in ONH biomechanics, and motivate additional research to better define the in vivo effects of choroidal volume change.
脉络膜的几何形状和肿胀被认为会导致眼部病变。因此，了解脉络膜如何影响视神经乳头（ONH）的生物力学环境非常重要。我们开发了一种有限元模型来研究急性脉络膜肿胀和脉络膜几何形状如何影响 ONH 变形。
我们开发了两种 ONH 的几何模型：一种是“钝”脉络膜插入，另一种是“锥形”脉络膜插入。我们研究了脉络膜体积变化（估计在眼球脉冲期间发生 2.1-14.2μL）如何影响三个组织区域的生物力学应变：前层神经组织、筛板和后层神经组织。然后，我们进行了敏感性分析，以了解 ONH 压力、组织材料特性和脉络膜肿胀如何影响组织的峰值应变。
在钝状脉络膜几何形状中，脉络膜肿胀对前层神经组织的应变有很大影响，其大小与由于 IOP 为 30mmHg 而预期发生的应变相当。在锥形脉络膜几何形状中，脉络膜肿胀也会影响应变，但程度小于钝状几何形状。敏感性分析证实，在钝状脉络膜几何形状中，脉络膜肿胀对前层神经组织的应变影响更大。
脉络膜解剖结构和肿胀可以相互作用，在眼内压前层神经组织变形中发挥重要作用。这些发现表明，脉络膜可能在 ONH 生物力学中发挥重要的、以前未被认识到的作用，并促使进行更多的研究以更好地定义脉络膜体积变化的体内影响。
