Surface wave elastometry of the cornea in porcine and human donor eyes.
Surface wave elastometry of the cornea in porcine and human donor eyes.
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DOI：
10.3928/1081-597x-20070101-11
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发表时间：
2007
影响因子：
2.4
通讯作者：
W. Dupps;M. Netto;S. Herekar;R. Krueger
中科院分区：
文献类型：
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作者：
W. Dupps;M. Netto;S. Herekar;R. Krueger
目的介绍一种非破坏性的角膜硬度表征技术，确定测量精度，并研究猪角膜沿沿着和周向向量的比较硬度值。还研究了上皮清创、松弛切口和交联介导的硬化对表面波速度的影响。方法采用手持式原型系统测量超声表面波在两个固定距离换能器之间沿十位置图沿着的传播时间。在6个猪角膜中重复测量，评估重复性。在12个控制眼内压（IOP）的猪眼球中，在上皮去除之前和之后，然后在250和750微米深的松弛切口之后进行系列测量。在玻璃体内压恒定的人眼球中，比较胶原交联前后的中心波速度和经角膜IOP测量值。结果所有地区的测量重复性在2.2%和8.1%之间。上皮细胞去除导致67%的眼睛测量硬度增加，但统计功效不足以检测系统性变化。在250微米角膜切开术后，穿过中央切口的波速度显著降低（P <0.001），但在更深的角膜切开术后，波速度没有进一步显著降低。角膜切开术后检测到与耦合效应一致的子午线刚度变化。尽管维持恒定的IOP，但胶原交联后表面波速度和经角膜IOP测量值显著增加。结论：在体外实验中，手持式角膜弹性测量仪可重复测量松弛切口和胶原交联后的局部硬度变化。表面波弹性测量允许对与屈光手术、扩张性疾病和青光眼相关的角膜生物力学特性进行局部评估。
PURPOSE To introduce a nondestructive technique for characterization of corneal stiffness, determine measurement precision, and investigate comparative stiffness values along central, radial, and circumferential vectors in porcine corneas. The effects of epithelial debridement, relaxing incisions, and crosslink-mediated stiffening on surface wave velocity are also studied. METHODS A handheld prototype system was used to measure ultrasound surface wave propagation time between two fixed-distance transducers along a ten-position map. Repeatability was assessed with replicate measurements in 6 porcine corneas. In 12 porcine globes with controlled intraocular pressure (IOP), serial measurements were performed before and after epithelial removal, then after 250- and 750-microm-deep relaxing incisions. In human globes with constant intravitreal pressure, central wave velocity and transcorneal IOP measurements were compared before and after collagen cross-linking. RESULTS Measurement repeatability across all regions was between 2.2% and 8.1%. Epithelial removal resulted in increases in measured stiffness in 67% of eyes, but statistical power was insufficient to detect a systematic change. Wave velocity across a central incision decreased significantly after 250-microm keratotomy (P < .001), but did not undergo a significant further decrease with deeper keratotomy. Meridional stiffness changes consistent with coupling effects were detected after keratotomy. Surface wave velocity and transcorneal IOP measurements increased markedly after collagen cross-linking despite maintenance of a constant IOP. CONCLUSIONS Handheld corneal elastometry provides a repeatable measure of regional stiffness changes after relaxing incisions and collagen cross-linking in in vitro experiments. Surface wave elastometry allows focal assessment of corneal biomechanical properties that are relevant in refractive surgery, ectatic disease, and glaucoma.