Purpose

With active investigation underway for embedded-circuit contact lenses, safe oxygen supply of these novel lenses remains a question. Central-to-peripheral corneal edema for healthy eyes during wear of soft contact (SCL) and scleral lenses (SL) with embedding components is assessed.

Methods

Various 2-dimensional (2D) designs of SL and SCL with embedded components are constructed on Comsol Multiphysics 5.5. Local corneal swelling associated with the designed lenses is determined by a recently developed 2D metabolic-swelling model. Settled central post-lens tear-film thicknesses (PoLTFs) are set at 400 μm and 3 μm for SL and SCL designs, respectively. Each lens design has an axisymmetric central and an axisymmetric peripheral embedment. Oxygen permeability (Dk) of the lens and the embedments ranges from 0 to 200 Barrer. Dimensions and location of the embedments are varied to assess optimal-design configurations to minimize central-to-peripheral corneal edema.

Results

By adjusting oxygen Dk of the central embedment, the peripheral embedment, or the lens matrix polymer, corneal swelling is reduced by up to 2.5 %, 1.5 %, or 1.4 % of the baseline corneal thickness, respectively, while keeping all other parameters constant. A decrease in PoLTF thickness from 400 μm to 3 μm decreases corneal edema by up to 1.8 % of the baseline corneal thickness. Shifting the peripheral embedment farther out towards the periphery and towards the anterior lens surface reduces peak edema by up to 1.3 % and 0.6 % of the baseline corneal thickness, respectively.

Conclusions

To minimize central-to-peripheral corneal edema, embedments should be placed anteriorly and far into the periphery to allow maximal limbal metabolic support and oxygen transport in the polar direction (i.e., the θ-direction in spherical coordinates). High-oxygen transmissibility for all components and thinner PoLTF thickness are recommended to minimize corneal edema. Depending on design specifications, less than 1 % swelling over the entire cornea is achievable even with oxygen-impermeable embedments.

中文翻译：

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嵌入式组件隐形眼镜佩戴过程中中央至周边角膜水肿

目的

随着对嵌入式隐形眼镜的积极研究，这些新型镜片的安全氧气供应仍然是一个问题。评估佩戴有嵌入组件的软性接触（SCL）和巩膜片（SL）佩戴过程中，健康眼睛的中央到周围角膜水肿。

方法

具有嵌入式组件的SL和SCL的各种二维（2D）设计是在Comsol Multiphysics 5.5上构建的。与设计的晶状体相关的局部角膜肿胀是由最近开发的2D代谢溶胀模型确定的。对于SL和SCL设计，沉降的中央透镜后泪膜厚度（PoLTFs）分别设置为400μm和3μm。每个镜片设计都有一个轴对称的中心和一个轴对称的外围嵌入物。晶状体和嵌入物的透氧率（Dk）在0到200 Barrer之间。嵌入物的尺寸和位置可以变化，以评估最佳设计配置，以最大程度地减少中央到周围的角膜浮肿。

结果

通过调节中央嵌入物，周边嵌入物或晶状体聚合物的氧Dk，在保持所有其他参数不变的情况下，角膜肿胀分别可减少多达基线角膜厚度的2.5％，1.5％或1.4％。PoLTF厚度从400μm减小到3μm可使角膜水肿最多减少基线角膜厚度的1.8％。将周边嵌入物移向周边和晶状体前表面更远，分别使峰值水肿分别减少基线角膜厚度的1.3％和0.6％。

结论

为了最大程度地减少中央到周围的角膜水肿，应将植入物放置在前部且远至周围，以最大程度地获得角膜缘代谢支持和氧在极性方向（即，球坐标中的θ方向）的运输。建议所有组件都具有较高的氧气透过率，并且PoLTF厚度应更薄，以最大程度地减少角膜浮肿。根据设计规范，即使使用不透氧的嵌入物，在整个角膜上的溶胀也可达到不到1％。