Berjano Enrique J, Saiz Javier, Ferrero José M
Departamento de Ingeniería Electrónica, Universidad Politécnica de Valencia, Spain.
IEEE Trans Biomed Eng. 2002 Mar;49(3):196-205. doi: 10.1109/10.983453.
We present a theoretical model for the study of cornea heating with radio-frequency currents. This technique is used to reshape the cornea to correct refractive disorders. Our numerical model has allowed the study of the temperature distributions in the cornea and to estimate the dimensions of the lesion. The model incorporates a fragment of cornea, aqueous humor, and the active electrode placed on the cornea surface. The finite element method has been used to calculate the temperature distribution in the cornea by solving a coupled electric-thermal problem. We analyzed by means of computer simulations the effect of: a) temperature influence on the tissue electrical conductivity; b) the dispersion of the biological characteristics; c) the anisotropy of the cornea thermal conductivity; d) the presence of the tear film; and e) the insertion depth of the active electrode in the cornea, and the results suggest that these effects have a significant influence on the temperature distributions and thereby on the lesion dimensions. However, the cooling of the aqueous humor in the endothelium or the realistic value of the cornea curvature did not have a significant effect on the temperature distributions. An experimental model based on the lesions created in rabbit eyes has been used in order to compare the theoretical and experimental results. There is a tendency toward the agreement between experimental and theoretical results, although we have observed that the theoretical model overestimates the lesion dimension.
我们提出了一个用于研究射频电流对角膜加热的理论模型。该技术用于重塑角膜以矫正屈光不正。我们的数值模型能够研究角膜中的温度分布，并估计损伤的尺寸。该模型包含一块角膜、房水以及置于角膜表面的有源电极。通过求解电热耦合问题，使用有限元方法计算角膜中的温度分布。我们通过计算机模拟分析了以下因素的影响：a）温度对组织电导率的影响；b）生物学特性的离散性；c）角膜热导率的各向异性；d）泪膜的存在；e）有源电极在角膜中的插入深度，结果表明这些因素对温度分布有显著影响，进而对损伤尺寸有显著影响。然而，内皮中房水的冷却或角膜曲率的实际值对温度分布没有显著影响。为了比较理论和实验结果，我们使用了基于兔眼所产生损伤的实验模型。尽管我们观察到理论模型高估了损伤尺寸，但实验结果和理论结果仍有趋于一致的趋势。
