Singapore Eye Research Institute and Singapore National Eye Center, Singapore.
Department of Biomedical Engineering, National University of Singapore, Singapore.
Invest Ophthalmol Vis Sci. 2019 Jun 3;60(7):2690-2695. doi: 10.1167/iovs.18-26455.
To evaluate the biomechanical properties (Young's modulus) of normal (control) and glaucomatous human iris using atomic force microscopy (AFM).
Iris tissue obtained from eighteen glaucomatous subjects (equal number of eyes with primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) and five normal subjects who underwent elective eye surgery were subjected to the estimation of Young's modulus by AFM. Force measurements were done at room temperature using Nanowizard II BioAFM. The iris samples were immersed in the liquid media (PBS with 0.1% BSA) during force measurements. Young's modulus values were calculated for each recorded curve using JPK Data Processing Software, which uses a Hertz's contact model for spherical indenters fitted to the extend curves.
The iris from the normal controls had the least Young's modulus (0.85 ± 0.31 kPa) while those from PACG patients had the highest Young's modulus (2.40 ± 0.82 kPa). The Young's modulus of PACG iris was significantly higher compared to that of the normal controls (P = 0.005) and POAG iris (P = 0.001). However, there was no significant difference in the Young's modulus of POAG iris (1.13 ± 0.36 kPa) compared to that of the normal controls (P = 0.511).
Variations in biomechanical properties of iris tissue may have a significant role in the pathogenesis of angle closure glaucoma. This study suggests the existence of fundamental biomechanical differences in eyes with angle closure versus open angle glaucoma. An understanding of this basis creates a new platform to understand disease pathology better and work on therapeutic strategies that will address the same.
使用原子力显微镜（AFM）评估正常（对照）和青光眼人虹膜的生物力学特性（杨氏模量）。
对 18 名青光眼患者（原发性闭角型青光眼（PACG）和原发性开角型青光眼（POAG）各 9 只眼）和 5 名接受选择性眼部手术的正常受试者的虹膜组织进行了杨氏模量的 AFM 估计。在室温下使用 Nanowizard II BioAFM 进行力测量。在力测量过程中，将虹膜样本浸入液体介质（含 0.1%BSA 的 PBS）中。使用 JPK 数据处理软件为每个记录曲线计算杨氏模量，该软件使用适合扩展曲线的球形压头 Hertz 接触模型。
正常对照组的虹膜具有最小的杨氏模量（0.85±0.31kPa），而 PACG 患者的虹膜具有最高的杨氏模量（2.40±0.82kPa）。PACG 虹膜的杨氏模量明显高于正常对照组（P=0.005）和 POAG 虹膜（P=0.001）。然而，POAG 虹膜的杨氏模量（1.13±0.36kPa）与正常对照组相比无显著差异（P=0.511）。
虹膜组织生物力学特性的变化可能在闭角型青光眼的发病机制中起重要作用。本研究表明，闭角型和开角型青光眼的眼睛存在基本的生物力学差异。对这种基础的理解为更好地了解疾病病理学并开展针对该疾病的治疗策略创造了新的平台。
