Department of Ophthalmology, NYU Langone Health, New York, New York, United States.
Department of Biomedical Engineering, NYU Tandon School of Engineering, New York, New York, United States.
Invest Ophthalmol Vis Sci. 2022 May 2;63(5):25. doi: 10.1167/iovs.63.5.25.
The lamina cribrosa (LC) is a leading target for initial glaucomatous damage. We investigated the in vivo microstructural deformation within the LC volume in response to acute IOP modulation while maintaining fixed intracranial pressure (ICP).
In vivo optic nerve head (ONH) spectral-domain optical coherence tomography (OCT) scans (Leica, Chicago, IL, USA) were obtained from eight eyes of healthy adult rhesus macaques (7 animals; ages = 7.9-14.4 years) in different IOP settings and fixed ICP (8-12 mm Hg). IOP and ICP were controlled by cannulation of the anterior chamber and the lateral ventricle of the brain, respectively, connected to a gravity-controlled reservoir. ONH images were acquired at baseline IOP, 30 mm Hg (H1-IOP), and 40 to 50 mm Hg (H2-IOP). Scans were registered in 3D, and LC microstructure measurements were obtained from shared regions and depths.
Only half of the eyes exhibited LC beam-to-pore ratio (BPR) and microstructure deformations. The maximal BPR change location within the LC volume varied between eyes. BPR deformer eyes had a significantly higher baseline connective tissue volume fraction (CTVF) and lower pore aspect ratio (P = 0.03 and P = 0.04, respectively) compared to BPR non-deformer. In all eyes, the magnitude of BPR changes in the anterior surface was significantly different (either larger or smaller) from the maximal change within the LC (H1-IOP: P = 0.02 and H2-IOP: P = 0.004).
The LC deforms unevenly throughout its depth in response to IOP modulation at fixed ICP. Therefore, analysis of merely the anterior LC surface microstructure will not fully capture the microstructure deformations within the LC. BPR deformer eyes have higher CTVF than BPR non-deformer eyes.
筛板（LC）是原发性青光眼损伤的主要靶标。我们研究了在保持固定颅内压（ICP）的情况下，急性眼压调节时 LC 体积内的微观结构变形。
在不同的眼压设置和固定 ICP（8-12mmHg）下，从 7 只健康成年猕猴（7 只动物；年龄为 7.9-14.4 岁）的 8 只眼睛中获得活体视神经头（ONH）频域光学相干断层扫描（OCT）扫描（Leica，芝加哥，IL，美国）。通过分别连接到重力控制储液器的前房和大脑侧脑室的插管来控制 IOP 和 ICP。在基础 IOP、30mmHg（H1-IOP）和 40 至 50mmHg（H2-IOP）下获取 ONH 图像。对扫描进行 3D 注册，并从共享区域和深度获取 LC 微观结构测量值。
只有一半的眼睛表现出 LC 梁孔比（BPR）和微观结构变形。LC 体积内的最大 BPR 变化位置在眼睛之间有所不同。与 BPR 非变形者相比，BPR 变形眼的基础结缔组织体积分数（CTVF）显着更高（分别为 P=0.03 和 P=0.04），而孔隙度长宽比（Pore aspect ratio，PAR）更低（分别为 P=0.03 和 P=0.04）。在所有眼睛中，前表面 BPR 变化的幅度与 LC 内的最大变化（H1-IOP：P=0.02 和 H2-IOP：P=0.004）明显不同（要么更大，要么更小）。
在固定 ICP 下，LC 会在整个深度上不均匀地变形以响应 IOP 调节。因此，仅分析 LC 前表面的微观结构将不能完全捕获 LC 内的微观结构变形。与 BPR 非变形眼相比，BPR 变形眼的 CTVF 更高。
