Czerpak Cameron A, Kashaf Michael Saheb, Zimmerman Brandon K, Mirville Rebecca, Gasquet Nicolas C, Quigley Harry A, Nguyen Thao D
Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD, USA.
Wilmer Ophthalmological Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Transl Vis Sci Technol. 2024 Dec 2;13(12):7. doi: 10.1167/tvst.13.12.7.
The purpose of this study was to measure biomechanical strains in the lamina cribrosa (LC) of living human eyes undergoing intraocular pressure (IOP) increase.
Healthy control subjects and patients with glaucoma underwent optical coherence tomographic (OCT) imaging of the LC before and after wearing of swim goggles that increased IOP (57 image pairs, 39 persons). Digital volume correlation was used to measure biomechanical strains in optic nerve head tissue and change in depth of the anterior border of the LC.
The mean IOP increase in both glaucoma and control eyes was 7.1 millimeters of mercury (mm Hg) after application of the goggles. Among glaucoma eyes, strains that were significant were: contractile Ezz (average = -0.33%, P = 0.0005), contractile Eθθ (average = -0.23%, P = 0.03), Emax (average = 0.83%, P < 0.0001), and Γmax (average = 0.95%, P < 0.0001), whereas the average anterior LC depth (ALD) decreased by 2.39 µm (anterior; P = 0.0002). In glaucoma eyes, shear strain Ezθ was greater with worse mean deviation (MD) and visual function index (P = 0.044 and P = 0.006, respectively, multivariate models). Strain compliance for Erθ, Ezθ, and Eθθ all increased with greater MD worsening prior to imaging (P = 0.04, P = 0.007, and P = 0.03).
LC strains were measurable 20 minutes after IOP increase, producing axial compression and greater peripheral strain than centrally. Some strain compliances were greater with worse existing visual field loss or with more progressive past field loss.
Biomechanical strains are related to measures of glaucoma damage, supporting the hypothesis that optic nerve head biomechanical responses represent a noninvasive biomarker for glaucoma.
本研究旨在测量眼压（IOP）升高时活体人眼筛板（LC）的生物力学应变。
健康对照者和青光眼患者在佩戴增加眼压的泳镜前后接受了LC的光学相干断层扫描（OCT）成像（57对图像，39人）。使用数字体积相关技术测量视神经乳头组织中的生物力学应变以及LC前缘深度的变化。
佩戴泳镜后，青光眼和对照眼的平均眼压升高均为7.1毫米汞柱（mmHg）。在青光眼眼中，显著的应变包括：收缩性Ezz（平均值 = -0.33%，P = 0.0005）、收缩性Eθθ（平均值 = -0.23%，P = 0.03）、Emax（平均值 = 0.83%，P < 0.0001）和Γmax（平均值 = 0.95%，P < 0.0001），而平均LC前缘深度（ALD）减少了2.39 µm（向前；P = 0.0002）。在青光眼眼中，平均偏差（MD）和视觉功能指数越差，剪切应变Ezθ越大（多变量模型中分别为P = 0.044和P = 0.006）。在成像前，随着MD恶化程度增加，Erθ、Ezθ和Eθθ的应变顺应性均增加（P = 0.04、P = 0.007和P = 0.03）。
眼压升高20分钟后可测量到LC应变，产生轴向压缩，且周边应变大于中央应变。一些应变顺应性在现有视野损失越严重或过去视野损失进展越大时越高。
生物力学应变与青光眼损伤的测量相关，支持视神经乳头生物力学反应代表青光眼非侵入性生物标志物的假说。
