Ophthalmic Engineering & Innovation Laboratory, Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore.
Ophthalmic Engineering & Innovation Laboratory, Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore; Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
Exp Eye Res. 2019 Apr;181:190-196. doi: 10.1016/j.exer.2019.02.005. Epub 2019 Feb 7.
Current literature has not considered or provided any data on the permeability of the iris stroma. In this study, we aimed to determine the hydraulic permeability of porcine irides from the isolated stroma. Fifteen enucleated porcine eyes were acquired from the local abattoir. The iris pigment epithelium was scraped off using a pair of forceps and the dilator muscles were pinched off using a pair of colibri toothed forceps. We designed an experimental setup, based on Darcy's law, and consisting of a custom 3D-printed pressure column using acrylonitrile butadiene styrene (ABS) plastic. PBS solution was passed through the iris stroma in a 180° arc shape, with a column height of approximately 204 mm (2000 Pa). Measurements of iris stromal thickness were conducted using optical coherence tomography (OCT). To measure flow rate, we measured the mass (volume) of PBS solution using a mass balance in approximately 1 min. Histology was performed using hematoxylin and eosin (H&E) and anti-smooth muscle antibody (anti-α-SMA) for validation. The permeability experiments demonstrated that the iris stroma is a biphasic tissue that allows fluid flow. Our image processing results determined the area of flow to be 7.55 mm and the tissue thickness to be between 180 and 430 μm. The hydraulic permeability of the porcine stroma, calculated using Darcy's law, was 5.13 ± 2.39 × 10 mm/Pa•s. Histological and immunochemical studies confirmed that the tissues used for this permeability study were solely iris stroma. Additionally, anti-α-SMA staining revealed staining specific for stromal blood vessels, with the notable absence of dilator and sphincter muscle staining. Our study combined experimental microscopic data with the theory of biphasic materials to investigate the hydraulic permeability of the iris stroma. This work will serve as a basis on which to validate future biomechanical studies of human irides with which may ultimately aid disease diagnosis and inform the design of novel treatments.
目前的文献尚未考虑或提供有关虹膜基质通透性的任何数据。在这项研究中，我们旨在从分离的基质中确定猪虹膜的水力渗透率。从当地屠宰场获得了 15 只去眼猪眼。使用一对镊子刮除虹膜色素上皮，并用一对 Colibri 齿状镊子夹住扩瞳肌。我们设计了一个实验装置，基于达西定律，由使用丙烯腈丁二烯苯乙烯（ABS）塑料的定制 3D 打印压力柱组成。PBS 溶液以 180°弧形通过虹膜基质，柱高约为 204mm（2000Pa）。使用光学相干断层扫描（OCT）测量虹膜基质厚度。为了测量流速，我们使用质量天平在大约 1 分钟内测量 PBS 溶液的质量（体积）。使用苏木精和伊红（H&E）和抗平滑肌抗体（抗-α-SMA）进行组织学验证。通透性实验表明，虹膜基质是一种允许流体流动的双相组织。我们的图像处理结果确定流动面积为 7.55mm，组织厚度在 180 至 430μm 之间。使用达西定律计算出的猪基质水力渗透率为 5.13±2.39×10mm/Pa•s。组织学和免疫化学研究证实，用于该通透性研究的组织仅为虹膜基质。此外，抗-α-SMA 染色显示仅对基质血管有特异性染色，而扩瞳肌和括约肌无明显染色。我们的研究将实验显微镜数据与双相材料理论相结合，研究了虹膜基质的水力渗透率。这项工作将为未来对人类虹膜的生物力学研究提供基础，最终可能有助于疾病诊断并为新型治疗方法提供信息。
