Department of Medical Education, Taichung Veterans General Hospital, Taichung, Taiwan.
Department of Medical Education, Changhua-Christian Hospital, Changhua, Taiwan.
Technol Health Care. 2024;32(6):4109-4121. doi: 10.3233/THC-231983.
To avoid risks of mucosal infection from contact lenses removal, a contact lens plunger is often used.
Given various types of contact lens plungers available on the market, no study has yet been done on mechanical effects of the contact lens plunger on contact lens removal. Here, this study used finite element analysis to investigate the effects of plunger size and plunger position on the removal of soft and rigid gas permeable (RGP) contact lenses.
First, we established finite element analysis models for the plunger, contact lens, cornea, and aqueous humor. The plunger is made of mostly silicone rubber, and the contact lenses are mainly made of soft and hard material. The part of the plunger used for removal was located either at the central or the edged position, with pulling 1 mm distance. The main parameters observation indicators of in this study were the reaction force at the fixed end of the cornea, aqueous humor, the von Mises stress of the plunger, the contact lenses, and the cornea.
Results of this study showed that when a plunger of a larger diameter was used, the reaction force of the plunger was also larger, especially when applied to RGP lenses, which required a slightly larger force (∼0.27 N). Also, when removing a RGP lens from the edge, there was a greater stress at the edge of the contact lens (2.5799 MPa), and this caused a higher stress on both the cornea (0.0165 MPa) and the aqueous humor (0.00114 MPa).
When using a plunger with a larger diameter to remove a RGP lens, although a larger force required, the relatively larger contact area likely reduced the stress on the cornea and aqueous humor, thereby reducing the risk of eye injury. In addition, when removing a RGP lens, the results of this study recommended it to be removed from the plunger edge, as that facilitated the removal of contact lens.
为避免因接触镜取出而导致的黏膜感染风险，常使用接触镜顶出器。
鉴于市售接触镜顶出器种类繁多，尚未有研究探讨接触镜顶出器对接触镜取出的力学影响。本研究采用有限元分析方法，研究顶出器尺寸和顶出器位置对软镜和硬性透气性（RGP）接触镜取出的影响。
首先，我们建立了顶出器、接触镜、角膜和房水的有限元分析模型。顶出器主要由硅橡胶制成，接触镜主要由软质和硬质材料制成。用于取出的顶出器部分位于中央或边缘位置，拉动距离为 1mm。本研究的主要观察指标是角膜固定端、房水的反作用力、顶出器、接触镜和角膜的 von Mises 应力。
研究结果表明，使用较大直径的顶出器时，顶出器的反作用力也较大，特别是在使用 RGP 镜片时，需要稍微大一点的力（约 0.27N）。另外，从边缘取出 RGP 镜片时，接触镜边缘的应力较大（2.5799MPa），这导致角膜（0.0165MPa）和房水（0.00114MPa）的应力更高。
使用较大直径的顶出器取出 RGP 镜片时，虽然需要更大的力，但较大的接触面积可能会降低角膜和房水的应力，从而降低眼损伤的风险。此外，在取出 RGP 镜片时，本研究建议从顶出器边缘取出，因为这样更容易取出接触镜。
