Biomedical Atomic Force Microscopy Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, McArthur Engineering Annex Room 170A, Coral Gables, FL 33146, USA.
Exp Eye Res. 2013 Oct;115:41-6. doi: 10.1016/j.exer.2013.06.004. Epub 2013 Jun 22.
Corneal biomechanics is an essential parameter for developing diagnostic and treatment methods of corneal-related diseases. It is widely accepted that corneal mechanical strength stems from the stroma's collagenous composition. However, more comprehensive insight into the mechanical properties within the stroma is needed to improve current corneal diagnostic and treatment techniques. The purpose of this study was to perform elasticity characterization of anterior and posterior stromal regions of human corneas using atomic force microscopy (AFM). Nine pairs of human whole globes were placed in 20% Dextran solution, cornea side down, to restore the corneal thickness to physiological levels (400-600 μm). The epithelium and Bowman's membrane were removed from all eyes. Anterior stromal AFM elasticity testing was then performed on left (OS) eyes. Additional stroma was removed from right (OD) eyes to allow posterior stromal measurements at a depth of 50% of the original thickness. All experiments were performed with corneas submerged in 15% Dextran to maintain corneal hydration. The results of the study showed that the Young's modulus of elasticity of the anterior stroma (average: 281 ± 214 kPa; range: 59-764 kPa) was significantly higher than that of the posterior stroma (average: 89.5 ± 46.1 kPa; range: 29-179 kPa) (p = 0.014). In addition, a linear relationship was found between the posterior stromal elasticity and anterior stromal elasticity (p = 0.0428). On average, the elasticity of the posterior stroma is 39.3% of the anterior stroma. In summary, there appears to be an elasticity gradient within the corneal stroma, which should be considered in the design and development of corneal diagnostic and treatment methods to enhance efficacy.
角膜生物力学是开发与角膜相关疾病的诊断和治疗方法的重要参数。人们普遍认为，角膜的机械强度源于基质的胶原组成。然而，为了改进当前的角膜诊断和治疗技术，需要更全面地了解基质内的机械性能。本研究旨在使用原子力显微镜（AFM）对人眼角膜的前基质和后基质区域进行弹性特性表征。将 9 对人眼整个眼球置于 20% Dextran 溶液中，角膜朝下，以将角膜厚度恢复至生理水平（400-600μm）。所有眼睛的上皮和Bowman 膜均被去除。然后对左眼（OS）进行前基质 AFM 弹性测试。从右眼（OD）去除额外的基质，以使在后基质厚度的 50%深度处进行测量。所有实验均在角膜浸在 15%Dextran 中的情况下进行，以保持角膜水合作用。研究结果表明，前基质（平均：281±214kPa；范围：59-764kPa）的杨氏弹性模量明显高于后基质（平均：89.5±46.1kPa；范围：29-179kPa）（p=0.014）。此外，在后基质弹性与前基质弹性之间发现了线性关系（p=0.0428）。平均而言，后基质的弹性为前基质的 39.3%。总之，角膜基质内似乎存在弹性梯度，在设计和开发角膜诊断和治疗方法时应考虑这一点，以提高疗效。
