Corneal stromal elasticity and viscoelasticity assessed by atomic force microscopy after different cross linking protocols.
Corneal stromal elasticity and viscoelasticity assessed by atomic force microscopy after different cross linking protocols.
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DOI：
10.1016/j.exer.2015.06.015
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发表时间：
2015-09
影响因子：
3.4
通讯作者：
Ziebarth NM
中科院分区：
文献类型：
--
作者：
Dias J;Diakonis VF;Lorenzo M;Gonzalez F;Porras K;Douglas S;Avila M;Yoo SH;Ziebarth NM
本研究的目的是评估弹性和粘弹性的前和更深的基质区域的角膜交联后，与三种不同的协议，使用原子力显微镜（AFM）通过压痕。本研究共使用40只猪角膜，分为4组（每组10个角膜）：控制（无治疗），德累斯顿（角膜上皮清创，核黄素预处理30分钟，3 mw/cm 2 UVA照射30分钟），加速（角膜上皮清创术，核黄素预处理30分钟和30 mw/cm 2 UVA照射3分钟），和京尼平（角膜上皮清创术和将前表面浸没在1%京尼平溶液中4小时）。使用AFM通过压痕对所有角膜、前基质和200μm深度处的弹性和粘弹性进行定量。对照组、Dresden组、加速组和京尼平组前基质区的平均杨氏模量分别为0.60±0.58MPa、1.58 ±1.04MPa、0.86±0.46MPa和1.71±0.51MPa; 200μm时平均值分别为0.08±0.06MPa、0.08±0.04MPa、0.08 ± 0.04MPa、0.06±0.01MPa。仅在前部区域，用Dresden方案和京尼平交联的角膜比对照组显著更硬（p<0.05）。对照组、Dresden组、加速组和京尼平组前基质的平均表观粘度分别为88.2± 43.7kPa·s、8.3± 7.1kPa·s、8.1± 2.3kPa·s和9.5± 3.8kPa·s; 200μm时平均值分别为35.0± 3.7kPa·s、49.6± 35.1kPa·s、42.4± 17.6kPa·s和41.8± 37.6kPa·s。所有交联方案仅导致前部区域的粘度降低（p<0.05）。交联的影响似乎仅限于前角膜基质，并没有延伸到更深的基质区域。此外，与加速方案相比，Dresden和京尼平方案似乎产生更硬的前角膜基质。
The purpose of this study was to evaluate elasticity and viscoelasticity in the anterior and deeper stromal regions of the cornea after cross linking with three different protocols using atomic force microscopy (AFM) through indentation. A total of 40 porcine corneas were used in this study and were divided into 4 groups (10 corneas per group): control (no treatment), Dresden (corneal epithelial debridement, riboflavin pretreatment for 30 minutes and a 3mw/cm2 for 30 minutes UVA irradiation), accelerated (corneal epithelial debridement, riboflavin pretreatment for 30 minutes and a 30mw/cm2 for 3 minutes UVA irradiation), and genipin (corneal epithelial debridement and submersion of anterior surface in a 1% genipin solution for 4 hours). Elasticity and viscoelasticity were quantified using AFM through indentation for all corneas, for the anterior stroma and at a depth of 200μm. For the control, Dresden, accelerated, and Genipin groups, respectively, the average Young’s modulus for the anterior stromal region was 0.60±0.58MPa, 1.58 ±1.04MPa, 0.86±0.46MPa, and 1.71±0.51MPa; the average for the 200μm stromal depth was 0.08±0.06MPa, 0.08±0.04MPa, 0.08±0.04MPa, and 0.06±0.01MPa. Corneas crosslinked with the Dresden protocol and genipin were significantly stiffer than controls (p<0.05) in the anterior region only. For the control, Dresden, Accelerated, and Genipin groups, respectively, the average calculated apparent viscosity for the anterior stroma was 88.2±43.7kPa-s, 8.3±7.1kPa-s, 8.1±2.3kPa-s, and 9.5±3.8kPa-s; the average for the 200μm stromal depth was 35.0±3.7kPa-s, 49.6±35.1kPa-s, 42.4±17.6kPa-s, and 41.8±37.6kPa-s. All crosslinking protocols resulted in a decrease in viscosity in the anterior region only (p<0.05). The effects of cross-linking seem to be limited to the anterior corneal stroma and do not extend to the deeper stromal region. Additionally, the Dresden and genipin protocols seem to produce a stiffer anterior corneal stroma when compared to the accelerated protocol.