Research Institute of Eye Diseases, Moscow, Russia.
I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia.
Vestn Oftalmol. 2021;137(1):28-34. doi: 10.17116/oftalma202113701128.
Studies devoted to the assessment of lens capsule biomechanics can be divided into fundamental and applied. The former are oriented towards analysis of various indicators characterizing elasticity of the capsule as a basal membrane that maintains and changes the shape of the lens, and the latter deal with widespread introduction of modern microinvasive methods of phaco surgery into clinical practice.
To assess age-related changes in lens capsule biomechanics based on atomic force microscopy (AFM).
The study included 50 central fragments of the anterior capsule of the human lens obtained intraoperatively during ultrasonic phacoemulsification by continuous circular capsulorhexis. The measurements were carried out in the Fast Force Volume (FFV) mode. The force curves were processed in the Nanoscope Analysis software (Bruker, USA) using the Hertz model that allows calculating the Young's modulus of the capsule sample based on the dependence of the force on the puncture depth.
There was no statistically significant difference in the «stiffness» of the inner and outer surfaces before and after removal of the subcapsular epithelium (=0.25). In all cases, the inner surface of the capsule turned out to be «harder» than the outer one. In this case, the ratio of Young's modulus of the inner and outer surfaces has a significant dependence on age (<0.001). With an increase in age from 50 to 90 years, this ratio decreased from ~7 to ~1.5. This was due to a simultaneous change in Young's modulus of the opposite nature: an increase in the stiffness of the outer surface and its decrease in the inner one.
It is possible to assess lens capsule biomechanics using AFM if the subcapsular epithelium is present. In this case, the objects of study are the areas of the capsule free of epithelium, and the epithelial cells themselves can be used to identify the inner surface of the capsule. Regardless of age, the stiffness of the inner surface of the anterior lens capsule significantly exceeds that of the outer surface.
研究致力于评估晶状体囊生物力学可分为基础和应用。前者是面向于分析各种指标，作为基底膜的弹性的胶囊特征，维持和改变晶状体的形状，后者处理广泛引入现代微创方法的超声乳化白内障吸除术进入临床实践。
基于原子力显微镜（AFM）评估与年龄相关的晶状体囊生物力学变化。
该研究包括 50 个中央碎片的前囊晶状体人眼术中获得连续的环形撕囊术在超声乳化白内障吸除术中。测量在快速力体积（FFV）模式下进行。力曲线在 Nanoscope 分析软件（布鲁克，美国）中使用赫兹模型进行处理，该模型允许根据力与穿刺深度的关系计算囊样样本的杨氏模量。
在内、外表面的“硬度”在去除上皮前后没有统计学差异（=0.25）。在所有情况下，囊内表面的硬度比外表面的硬度高。在这种情况下，内、外表面杨氏模量之比与年龄有显著的依赖性（<0.001）。随着年龄从 50 岁增加到 90 岁，这一比例从7 降低到1.5。这是由于相反性质的杨氏模量变化的同时发生：外表面的硬度增加和内表面的硬度降低。
如果存在上皮下囊，使用 AFM 评估晶状体囊生物力学是可行的。在这种情况下，研究对象是没有上皮的囊区域，上皮细胞本身可用于识别囊的内表面。无论年龄大小，前晶状体囊内表面的硬度都显著大于外表面的硬度。
