Depto. de Ingeniería Mecánica, Energética y de los Materiales and Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, 06006, Badajoz, Spain.
Depto. de Expresión Gráfica, Universidad de Extremadura, 06006, Badajoz, Spain.
Biomech Model Mechanobiol. 2019 Apr;18(2):491-502. doi: 10.1007/s10237-018-1099-3. Epub 2018 Nov 28.
We study numerically the influence of an iris-fixed phakic intraocular lens (PIOL) on the transport of nutrients by the aqueous humor across a realistic model of the human eye. The Boussinesq equations are solved to calculate the velocity field both in the anterior and posterior chambers. The transport of the nutrient is modeled as that of a passive scalar convected by that velocity field and diffused by the concentration gradient. The nutrient is assumed to be adsorbed at the non-vascularized tissues, i.e., the crystalline lens and cornea endothelium. The adsorption rates at the crystalline and cornea endothelium are supposed to be proportional to the nutrient concentration there. The comparison between the results obtained with and without the PIOL allows us to quantify the influence of this device on the nutrient supply from the aqueous humor. The amount of nutrient adsorbed onto the crystalline is hardly affected by the presence of the PIOL in the anterior chamber, even though there is an iridotomy in this case. When the PIOL is implanted, the flux adsorbed onto the cornea endothelium increases up to around 32% for the highest value of the adsorption coefficient, and hardly varies for the other values of this parameter. This counterintuitive effect is explained by the efficient role played by the iridotomy in evacuating the nutrient from the posterior to the anterior chamber. Based on these results, one can estimate the variation of glucose available in the cornea endothelium after implanting the PIOL, and discuss potential effects on the cell metabolism. These simulations can be regarded as a first attempt to shed light on the mechanisms responsible for the supply of oxygen and glucose to eye avascular structures like the cornea endothelium and crystalline.
我们通过对人眼的真实模型数值研究了虹膜固定型有晶状体眼人工晶状体（PIOL）对房水营养物质运输的影响。通过求解 Boussinesq 方程计算前房和后房的速度场。将营养物质的运输建模为被动示踪剂在该速度场中对流和浓度梯度扩散。假设营养物质被非血管组织（即晶状体和角膜内皮）吸附。晶状体内皮和角膜内皮的吸附速率与该处的营养物质浓度成正比。将有和没有 PIOL 时的结果进行比较，使我们能够量化该设备对房水营养供应的影响。即使在前房中存在虹膜切开术，PIOL 也几乎不会影响到晶状体内吸附的营养物质的量。当 PIOL 植入时，对于最高吸附系数值，吸附到角膜内皮的营养物质通量增加了约 32%，而对于该参数的其他值几乎没有变化。这种反直觉的效果是由虹膜切开术在将营养物质从后房排到前房中所起的有效作用解释的。基于这些结果，可以估计植入 PIOL 后角膜内皮中可用葡萄糖的变化，并讨论对细胞代谢的潜在影响。这些模拟可以被视为首次尝试阐明为角膜内皮和晶状体等无血管结构提供氧气和葡萄糖的机制。
