Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom.
Invest Ophthalmol Vis Sci. 2012 Aug 7;53(9):5258-70. doi: 10.1167/iovs.12-9705.
The posterior sclera has a major biomechanical influence on the optic nerve head, and may therefore be important in glaucoma. Scleral material properties are influenced significantly by collagen fiber architecture. Here we quantitatively map fiber orientation in non-glaucoma and glaucoma posterior human sclerae.
Wide-angle x-ray scattering quantified fiber orientation at 0.5-mm intervals across seven non-glaucoma post-mortem human sclerae, and five sclerae with glaucoma history and confirmed axon loss. Multiphoton microscopy provided semiquantitative depth-profiling in the peripapillary sclera.
Midposterior fiber orientation was either uniaxial (one preferred direction) or biaxial (two directions). The peripapillary sclera was characterized by a ring of fibers located mainly in the mid-/outer stromal depth and encompassing ∼50% of the total tissue thickness. Fiber anisotropy was 37% higher in the peripapillary sclera compared with midposterior, varied up to 4-fold with position around the scleral canal, and was consistently lowest in the superior-nasal quadrant. Mean fiber anisotropy was significantly lower in the superior-temporal (P < 0.01) and inferior-nasal (P < 0.05) peripapillary scleral quadrants in glaucoma compared with non-glaucoma eyes.
The collagen fiber architecture of the posterior human sclera is highly anisotropic and inhomogeneous. Regional differences in peripapillary fiber anisotropy between non-glaucoma and glaucoma eyes may represent adaptive changes in response to elevated IOP and/or glaucoma, or baseline structural properties that associate with predisposition to glaucomatous axon damage. Quantitative fiber orientation data will benefit numerical eye models aimed at predicting the sclera's influence on nerve head biomechanics, and thereby its possible role in glaucoma.
后巩膜对视神经头有重要的生物力学影响，因此可能在青光眼的发病机制中起重要作用。巩膜的材料特性受胶原纤维结构的显著影响。在这里，我们定量绘制了非青光眼和青光眼人后巩膜的纤维取向。
广角 X 射线散射在 7 个非青光眼死后人类巩膜和 5 个有青光眼病史和证实轴突丧失的巩膜上以 0.5mm 的间隔定量纤维取向。多光子显微镜提供了在视盘周围巩膜的半定量深度分析。
中后段纤维取向为单轴（一个优先方向）或双轴（两个方向）。视盘周围巩膜的特征是位于中/外基质深度的纤维环，主要位于纤维环内，占总组织厚度的约 50%。与中后部相比，视盘周围巩膜的纤维各向异性高 37%，其位置在巩膜管周围变化高达 4 倍，在上方鼻象限始终最低。与非青光眼眼相比，青光眼眼的上方颞部（P<0.01）和下方鼻侧（P<0.05）视盘周围巩膜象限的平均纤维各向异性明显较低。
人后巩膜的胶原纤维结构具有高度各向异性和不均匀性。非青光眼和青光眼眼中视盘周围纤维各向异性的区域差异可能代表对眼压升高和/或青光眼的适应性变化，或者与青光眼性轴突损伤易感性相关的基线结构特性。定量纤维取向数据将有益于旨在预测巩膜对神经头生物力学影响的数值眼模型，从而可能在青光眼的发病机制中发挥作用。
