Mathematical Model to Compare the Relative Tensile Strength of the Cornea After PRK, LASIK, and Small Incision Lenticule Extraction
Mathematical Model to Compare the Relative Tensile Strength of the Cornea After PRK, LASIK, and Small Incision Lenticule Extraction
复制标题
DOI：
10.3928/1081597x-20130617-03
复制
发表时间：
2013-07-01
影响因子：
2.4
通讯作者：
Randleman, J. Bradley
中科院分区：
文献类型：
--
作者：
Reinstein, Dan Z.;Archer, Timothy J.;Randleman, J. Bradley
目的：建立一个数学模型来估计光屈光性角膜切除术（PRK）、LASIK和小切口晶状体摘除（SMILE）术后间质抗拉强度的相对差异。方法：利用先前发表的体外角膜基质抗拉强度作为深度函数的数据，建立数学模型，通过将数据拟合为四阶多项式函数来计算相对剩余抗拉强度，得到高相关系数（R-2 = 0.930）。计算该函数下的面积提供了总间质抗拉强度（TTS）的测量，仅基于PRK或LASIK的残余间质层和SMILE的透镜界面上下的残余间质层。结果：SMILE术后TTS最高，PRK次之，LASIK次之；例如，在切除100 μ m组织的550 μ m角膜中，SMILE （130 μ m帽）术后TTS为75%，PRK为68%，LASIK （110 μ m瓣）术后TTS为54%。在所有治疗类型中，薄角膜测厚术术后TTS均降低。在LASIK中，术后TTS随皮瓣厚度的增加而下降0.22%/ μ m，但SMILE中帽厚越大，TTS增加0.08%/ μ m。该模型预测SMILE晶状体厚度可以比LASIK消融深度大约100 μ m，并且仍然具有等效的角膜强度（相当于约7.75屈光度）。结论：该数学模型预测SMILE术后TTS明显高于PRK和LASIK，因为最强的前片保持完整。因此，SMILE应该能够矫正高度近视。
PURPOSE: To develop a mathematical model to estimate the relative differences in postoperative stromal tensile strength following photorefractive keratectomy (PRK), LASIK, and small incision lenticule extraction (SMILE).METHODS: Using previously published data where in vitro corneal stromal tensile strength was determined as a function of depth, a mathematical model was built to calculate the relative remaining tensile strength by fitting the data with a fourth order polynomial function yielding a high correlation coefficient (R-2 = 0.930). Calculating the area under this function provided a measure of total stromal tensile strength (TTS), based only on the residual stromal layer for PRK or LASIK and the residual stromal layers above and below the lenticule interface for SMILE.RESULTS: Postoperative TTS was greatest after SMILE, followed by PRK, then LASIK; for example, in a 550-mu m cornea after 100-mu m tissue removal, postoperative TTS was 75% for SMILE (130-mu m cap), 68% for PRK, and 54% for LASIK (110-mu m flap). The postoperative TTS decreased for thinner corneal pachymetry for all treatment types. In LASIK, the postoperative TTS decreased with increasing flap thickness by 0.22%/mu m, but increased by 0.08%/mu m for greater cap thickness in SMILE. The model predicted that SMILE lenticule thickness could be approximately 100 mu m greater than the LASIK ablation depth and still have equivalent corneal strength (equivalent to approximately 7.75 diopters).CONCLUSIONS: This mathematical model predicts that the postoperative TTS is considerably higher after SMILE than both PRK and LASIK, as expected given that the strongest anterior lamellae remain intact. Consequently, SMILE should be able to correct higher levels of myopia.